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Abstract Background Chronic obstructive pulmonary disease (COPD) is a significant global health issue, suspected to elevate the risk for various cancers. This study sought to discern whether COPD serves as a risk marker or a causative factor for prevalent cancers. Methods We employed univariable MR (UVMR) analyses to investigate the causal relationship between COPD and the top ten common cancers. Sensitivity analyses were performed to validate the main findings. Multivariable MR (MVMR) and two-step MR analyses were also conducted. False-discovery-rate (FDR) was used to correct multiple testing bias. Results The UVMR analysis demonstrated notable associations between COPD and lung cancer (odds ratio [OR] = 1.42, 95%CI 1.15–1.77, FDR = 6.37 × 10–3). This relationship extends to lung cancer subtypes such as squamous cell carcinoma (LUSC), adenocarcinoma (LUAD), and small cell lung cancer (SCLC). A tentative link was also identified between COPD and bladder cancer (OR = 1.53, 95%CI 1.03–2.28, FDR = 0.125). No significant associations were found between COPD and other types of cancer. The MVMR analysis that adjusted for smoking, alcohol drinking, and body mass index did not identify any significant causal relationships between COPD and either lung or bladder cancer. However, the two-step MR analysis indicates that COPD mediated 19.2% (95% CI 12.7–26.1%), 36.1% (24.9–33.2%), 35.9% (25.7–34.9%), and 35.5% (26.2–34.8%) of the association between smoking and overall lung cancer, as well as LUAD, LUSC, and SCLC, respectively. Conclusions COPD appears to act more as a risk marker than a direct cause of prevalent cancers. Importantly, it partially mediates the connection between smoking and lung cancer, underscoring its role in lung cancer prevention strategies.

ABSTRACT: Mesenchymal stem cells can differentiate into adipocyte precursor cells, and the balance of stem cell differentiation determines the quantity of adipocytes. Early-stage adipose tissue expression profiling revealed abnormal expression of DKK3 in the high-fat group. Moreover, DKK3 is enriched in the Wnt/β-catenin signaling pathway, and studies have shown that DKK3 can serve as a gene involved in early regulation of adipogenesis. Therefore, this study focuses on exploring how DKK3 regulates the molecular mechanism of adipocyte differentiation through the Wnt/β-catenin signaling pathway. In this experiment, the role of DKK3 in the differentiation of bone marrow mesenchymal stem cells into adipocyte precursors was validated using in vitro cultured chicken bone marrow mesenchymal stem cells. The results showed that overexpression of DKK3 led to a significant downregulation of Wnt/β-catenin signaling pathway-related marker gene expression (P < 0.05), a significant upregulation of adipogenic differentiation-related genes (P < 0.05), an increase in lipid droplet content, a significant increase in OD value (P < 0.05), a significant upregulation of mitochondrial oxidative respiratory-related marker gene expression (P < 0.05), and a significant downregulation of mitochondrial autophagy-related marker genes (P < 0.05). Conversely, the results were opposite after interfering with DKK3 gene expression. In this study, 4 SNP sites, including g.8419139, g.8419556, g.8419560, and g.8419598, were detected in the 7th exon of DKK3, among which the g.8419598 (C > T) site was significantly correlated with abdominal fat weight and abdominal fat rate in 100-day-old Ma Huang chickens (P < 0.001).

Abstract Objective To explore the efficacy of serplulimab plus chemotherapy in esophageal squamous cell carcinoma (ESCC) patients with liver metastases. Methods A post hoc exploratory analysis of ASTRUM‐007 study was performed, focusing on the association between the liver metastases status and the clinical outcomes. A systematic literature search of electronic databases was conducted to identify eligible randomized controlled trials for the meta‐analysis. Study‐level pooled analyses of hazard ratios (HRs) for PFS according to liver metastases were performed. Results The post hoc analysis of ASTRUM‐007 showed that although patients with liver metastases had a worse prognosis comparing with the non‐liver metastases patients in both treatment arms (serplulimab plus chemotherapy arm: median PFS, 5.7 vs. 6.6 months, HR 1.57 [95% CI, 1.15–2.13]; median OS, 13.7 vs. 15.3 months, HR 1.48 [95% CI, 1.09–1.98]; placebo plus chemotherapy arm: median PFS, 4.3 vs. 5.5 months, HR 1.58 [95% CI, 1.01–2.39]; median OS, 10.3 vs. 11.2 months, HR 1.32 [95% CI, 0.84–2.00]), OS and PFS benefits derived from serplulimab plus chemotherapy versus placebo plus chemotherapy in this study were observed in both patients with liver metastases (HR of PFS: 0.60; 95% CI, 0.37–0.97; HR of OS: 0.68; 95% CI, 0.43–1.11) and the non‐liver metastases patients (HR of PFS: 0.62; 95% CI, 0.49–0.80; HR of OS: 0.69; 95% CI, 0.55–0.87) with similar magnitude. Three randomized controlled trials were included in the meta‐analysis. Pooled HRs demonstrated that the addition of anti‐PD‐1 antibodies significantly improved PFS compared to chemotherapy alone regardless of liver metastases status. Conclusions This study reveals that the presence of liver metastases is a poor prognostic factor but does not affect the improvements in both PFS and OS brought by adding PD‐1 blockade to chemotherapy in ESCC patients. Predictive biomarkers for survival in these patients warrant further investigation.

Abstract Occult nodal metastasis (ONM) plays a significant role in comprehensive treatments of non-small cell lung cancer (NSCLC). This study aims to develop a deep learning signature based on positron emission tomography/computed tomography to predict ONM of clinical stage N0 NSCLC. An internal cohort (n = 1911) is included to construct the deep learning nodal metastasis signature (DLNMS). Subsequently, an external cohort (n = 355) and a prospective cohort (n = 999) are utilized to fully validate the predictive performances of the DLNMS. Here, we show areas under the receiver operating characteristic curve of the DLNMS for occult N1 prediction are 0.958, 0.879 and 0.914 in the validation set, external cohort and prospective cohort, respectively, and for occult N2 prediction are 0.942, 0.875 and 0.919, respectively, which are significantly better than the single-modal deep learning models, clinical model and physicians. This study demonstrates that the DLNMS harbors the potential to predict ONM of clinical stage N0 NSCLC.

Neoadjuvant chemoimmunotherapy has revolutionized the therapeutic strategy for non-small cell lung cancer (NSCLC), and identifying candidates likely responding to this advanced treatment is of important clinical significance. The current multi-institutional study aims to develop a deep learning model to predict pathologic complete response (pCR) to neoadjuvant immunotherapy in NSCLC based on computed tomography (CT) imaging and further prob the biologic foundation of the proposed deep learning signature. A total of 248 participants administrated with neoadjuvant immunotherapy followed by surgery for NSCLC at Ruijin Hospital, Ningbo Hwamei Hospital, and Affiliated Hospital of Zunyi Medical University from January 2019 to September 2023 were enrolled. The imaging data within 2 weeks prior to neoadjuvant chemoimmunotherapy were retrospectively extracted. Patients from Ruijin Hospital were grouped as the training set (n = 104) and the validation set (n = 69) at the 6:4 ratio, and other participants from Ningbo Hwamei Hospital and Affiliated Hospital of Zunyi Medical University served as an external cohort (n = 75). For the entire population, pCR was obtained in 29.4% (n = 73) of cases. The areas under the curve (AUCs) of our deep learning signature for pCR prediction were 0.775 (95% confidence interval [CI]: 0.649 - 0.901) and 0.743 (95% CI: 0.618 - 0.869) in the validation set and the external cohort, significantly superior than 0.579 (95% CI: 0.468 - 0.689) and 0.569 (95% CI: 0.454 - 0.683) of the clinical model. Furthermore, higher deep learning scores correlated to the upregulation for pathways of cell metabolism and more antitumor immune infiltration in microenvironment. Our developed deep learning model is capable of predicting pCR to neoadjuvant chemoimmunotherapy in patients with NSCLC.

Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity. Previous structure‒activity relationships indicated that triple halogenated depsidones display the best anti-pathogenic activity. However, the gene cluster and the tailoring steps responsible for halogenated depsidone nornidulin (3) remain enigmatic. In this study, we disclosed the complete biosynthetic pathway of the halogenated depsidone through in vivo gene disruption, heterologous expression and in vitro biochemical experiments. We demonstrated an unusual depside skeleton biosynthesis process mediated by both highly-reducing polyketide synthase and non-reducing polyketide synthase, which is distinct from the common depside skeleton biosynthesis. This skeleton was subsequently modified by two in-cluster enzymes DepG and DepF for the ether bond formation and decarboxylation, respectively. In addition, the decarboxylase DepF exhibited substrate promiscuity for different scaffold substrates. Finally, and interestingly, we discovered a halogenase encoded remotely from the biosynthetic gene cluster, which catalyzes triple-halogenation to produce the active end product nornidulin (3). These discoveries provide new insights for further understanding the biosynthesis of depsidones and their derivatives.

Recently, we re-isolated the glycosylated angucycline antibiotics P-1894B (1) and grincamycin (1′) from the marine-derived Streptomyces lusitanus SCSIO LR32 as potent antitumor agents and identified their biosynthesis gene cluster gcn. Both P-1894B (1) and grincamycin (1′) possess a trisaccharide and a disaccharide moiety comprised of five deoxysugars. In this work, three genes encoding glycosyltransferases (GcnG1, GcnG2, and GcnG3) responsible for the assembly of deoxysugars into angucycline aglycone were identified from the biosynthesis gene cluster gcn. Gene inactivations of gcnG1, gcnG2, gcnG3, and gcnG1G2 by lambda-RED-mediated gene replacements led to the construction of four mutants, in which the glycosyltransferase genes were disrupted, respectively. The metabolites from the mutants were purified and identified, including two new analogues designated as grincamycin U (3a) and V (3′). The sequential glycosylation steps in the biosynthesis of P-1894B (1) and grincamycin (1′) catalyzed by GcnG3, GcnG1, and GcnG2 were elucidated.

Abstract Purpose The clinical outcomes of delayed chest closure (DCC) compared with primary chest closure (PCC) following lung transplantation, including perioperative outcomes and long-term survival, remained controversial. This was the first systematic review and meta-analysis aimed to identify the short- and long-term outcomes of DCC following lung transplantation. Methods We comprehensively searched electronic literature from 4 databases up to April 1st, 2022. Dichotomous data and continuous data were pooled with odds ratio and weighted mean difference, respectively. The quality of included studies was assessed with the Newcastle–Ottawa Scale. Results Ten studies were included in the systematic review and 4 studies were included in the meta-analysis. Pooled analysis showed that DCC was associated with an increased risk of surgical site infection, prolonged hospital stays, and higher risk of primary graft dysfunction compared to PCC. The 30 day and 5 year survival were higher in PCC cohort compared with DCC cohort while differences in survival at 6 months was insignificant. Conclusion Our findings do not support the aggressive application of DCC. DCC should be cautiously applied since its association with worse perioperative outcomes and higher mortality. But it remains the life-saving steps under dangerous circumstances.

Lung adenocarcinoma (LUAD) is a malignant disease with an extremely poor prognosis, and there is currently a lack of clinical methods for early diagnosis and precise treatment and management. With the deepening of tumor research, more and more attention has been paid to the role of immune checkpoints (ICP) and long non-coding RNAs (lncRNAs) regulation in tumor development. Therefore, this study downloaded LUAD patient data from the TCGA database, and finally screened 14 key ICP-related lncRNAs based on ICP-related genes using univariate/multivariate COX regression analysis and LASSO regression analysis to construct a risk prediction model and corresponding nomogram. After multi-dimensional testing of the model, the model showed good prognostic prediction ability. In addition, to further elucidate how ICP plays a role in LUAD, we jointly analyzed the immune microenvironmental changes in LAUD patients and performed a functional enrichment analysis. Furthermore, to enhance the clinical significance of this study, we performed a sensitivity analysis of common antitumor drugs. All the above works aim to point to new directions for the treatment of LUAD.

Lung adenocarcinoma (LUAD), a malignant respiratory tumor with an extremely poor prognosis, has troubled the medical community all over the world. According to recent studies, fatty acid metabolism (FAM) and long non-coding RNAs (lncRNAs) regulation have shown exciting results in tumor therapy. In this study, the original LUAD patient data was obtained from the TCGA database, and 12 FAM-related lncRNAs (AL390755.1, AC105020.6, TMPO-AS1, AC016737.2, AC127070.2, LINC01281, AL589986.2, GAS6-DT, AC078993.1, LINC02198, AC007032.1, and AL021026.1) that were highly related to the progression of LUAD were finally identified through bioinformatics analysis, and a risk score model for clinical reference was constructed. The window explores the immunology and molecular mechanism of LUAD, aiming to shed the hoping light on LUAD treatment.

Marine-derived fungi are emerging as prolific workhorses of structurally novel natural products (NPs) with diverse bioactivities. However, the limitation of available selection markers hampers the exploration of cryptic NPs. Recyclable markers are therefore valuable assets in genetic engineering programs for awaking silent SM clusters. Here, both pyrG and amdS-based recyclable marker cassettes were established and successfully applied in marine-derived fungi Aspergillus sp. SCSIO SX7S7 and Spiromastix sp. SCSIO F190, respectively. Using pyrG recyclable marker, a markerless 7S7-∆depH strain with a simplified HPLC background was built by inactivating a polyketide synthase (PKS) gene depH and looping out the pyrG recyclable marker after depH deletion. Meanwhile, an amdS recyclable marker system was also developed to help strains that are difficult to use pyrG marker. By employing the amdS marker, a backbone gene spm11 responsible for one major product of Spiromastix sp. SCSIO F190 was inactivated, and the amdS marker was excised after using, generating a relatively clean F190-∆spm11 strain for further activation of novel NPs. The collection of two different recycle markers will guarantee flexible application in marine-derived fungi with different genetic backgrounds, enabling the exploitation of novel structures in various fungi species with different genome mining strategies.

Marine-derived fungi are emerging as attractive producers of structurally novel secondary metabolites with diverse bioactivities. However, the lack of efficient genetic tools limits the discovery of novel compounds and the elucidation of biosynthesis mechanisms. Here, we firstly established an effective PEG-mediated chemical transformation system for protoplasts in two marine-derived fungi, Spiromastix sp. SCSIO F190 and Aspergillus sp. SCSIO SX7S7. Next, we developed a simple and versatile CRISPR-Cas9-based gene disruption strategy by transforming a target fungus with a single plasmid. We found that the transformation with a circular plasmid encoding cas9, a single-guide RNA (sgRNA), and a selectable marker resulted in a high frequency of targeted and insertional gene mutations in both marine-derived fungal strains. In addition, the histone deacetylase gene rpd3 was mutated using the established CRISPR-Cas9 system, thereby activating novel secondary metabolites that were not produced in the wild-type strain. Taken together, a versatile CRISPR-Cas9-based gene disruption method was established, which will promote the discovery of novel natural products and further biological studies.

Streptomyces sp. SCSIO ZS0520 is a deep-sea hydrothermal vent-derived actinomycete. Our previous metabolism investigation showed that Streptomyces sp. SCSIO ZS0520 is a producer of cytotoxic actinopyrones. Here, another four types of secondary metabolites were identified, including six salinomycin isomers (2–7), the macrolide elaiophylin (8), the triterpene N-acetyl-aminobacteriohopanetriol (9), and the pyrone minipyrone (10). Among them, compounds 2–6 and 10 are new compounds. To understand the biosynthetic pathway of these compounds, a bioinformatic analysis of the whole genome was carried out, which identified 34 secondary metabolite biosynthetic gene clusters. Next, the biosynthetic pathways responsive to four types of products were deduced on the basis of gene function predictions and structure information. Taken together, these findings prove the metabolite potential of ZS0520 and lay the foundations to solve the remaining biosynthetic issues in four types of marine natural products.

Streptomyces niveus SCSIO 3406 was isolated from a sediment sample collected from South China Sea at a depth of 3536 m. Four new sesquiterpenoid naphthoquinones, marfuraquinocins A-D, and two new geranylated phenazines, i. e. phenaziterpenes A and B, were isolated from the fermentation broth of the strain. Here, we present its genome sequence, which contains 7,990,492 bp with a G+C content of 70.46% and harbors 7088 protein-encoding genes. The genome sequence analysis revealed the presence of a 28,787 bp gene cluster encoding for 24 open reading frames including 1,3,6,8-tetrahydroxynaphthalene synthase and monooxygenase, seven phenazine biosynthesis proteins, two prenyltransferases and a squalene-hopene cyclase. These genes are known to be necessary for the biosynthesis of both marfuraquinocins and phenaziterpenes. Outside the gene cluster (and scattered around the genome), there are seven genes belonging to the methylerythritol phosphate pathway for the biosynthesis of the essential primary metabolite, isopentenyl diphosphate, as well as six geranyl diphosphate/farnesyl diphosphate synthase genes. The strain S. niveus SCSIO 3406 showed type I PKS, type III PKS and nonribosomal peptide synthetase cluster. The sequence will provide the genetic basis for better understanding of biosynthesis mechanism of the above mentioned six compounds and for the construction of improved strain for the industrial production of antimicrobial agents.

Background and objective Mediastinal infection is a serious infection of mediastinal connective tissue, with more complications and higher mortality. Application of broad-spectrum antibiotics and nutritional support, early sufficient drainage is the key to successful treatment. In the mode of drainage, this paper discusses the application of continuous negative pressure drainage technique to treat acute anterior mediastinal infection of severe mouth pharynx source, and the good results are summarized and shared. Methods In January to December in 2017, a total of 17 cases treated acute mediastinal infection is derived from the throat, has formed a mediastinal abscess, surgery adopts retrosternal counterpart negative pressure drainage way, namely the sternum nest and free sternum xiphoid process under the incision on the first mediastinal clearance, make breakthrough and placed drainage device, suture closed wound, continuous negative pressure drainage, negative pressure using 3 cm-5 cm water column. Results Among the 17 patients, 14 patients were relieved by continuous negative pressure drainage, and then the drainage tube was removed. In 2 cases, the infection broke into the right thoracic cavity, and the closed drainage caused the negative pressure to disappear, and the negative pressure drainage was replaced by the conventional drainage, and the drainage tube was removed after the drainage tube was clear. One patient had formed a mediastinal abscess incision drainage time later, complicated with septic shock and sepsis, resulting in the death of multiple organ failure. Conclusion The traditional treatment of severe acute mediastinal infection is sternal incision and drainage. Continuous negative pressure drainage adequate drainage of mediastinal can relieve patients' pain, effusion, and avoid the dressing out repeatedly. It is an effective method. However, there are limitations in this method, which need to be further optimized.

Abstract Background The deep-sea-derived microbe Streptomyces koyangensis SCSIO 5802 produces neoabyssomicins A–B (1–2) and abyssomicins 2 (3) and 4 (4). Neoabyssomicin A (1) augments human immunodeficiency virus-1 (HIV-1) replication whereas abyssomicin 2 (3) selectively reactivates latent HIV and is also active against Gram-positive pathogens including methicillin-resistant Staphylococcus aureus (MRSA). Structurally, neoabyssomicins A–B constitute a new subtype within the abyssomicin family and feature unique structural traits characteristic of extremely interesting biosynthetic transformations. Results In this work, the biosynthetic gene cluster (BGC) for the neoabyssomicins and abyssomicins, composed of 28 opening reading frames, was identified in S. koyangensis SCSIO 5802, and its role in neoabyssomicin/abyssomicin biosynthesis was confirmed via gene inactivation and heterologous expression experiments. Bioinformatics and genomics analyses enabled us to propose a biosynthetic pathway for neoabyssomicin/abyssomicin biosynthesis. Similarly, a protective export system by which both types of compounds are secreted from the S. koyangensis producer was identified, as was a four-component ABC transporter-based import system central to neoabyssomicin/abyssomicin biosynthesis. Furthermore, two regulatory genes, abmI and abmH, were unambiguously shown to be positive regulators of neoabyssomicin/abyssomicin biosynthesis. Consistent with their roles as positive regulatory genes, the overexpression of abmI and abmH (independent of each other) was shown to improve neoabyssomicin/abyssomicin titers. Conclusions These studies provide new insight into the biosynthesis of the abyssomicin class of natural products, and highlight important exploitable features of its BGC for future efforts. Elucidation of the neoabyssomicin/abyssomicin BGC now enables combinatorial biosynthetic initiatives aimed at improving both the titers and pharmaceutical properties of these important natural products-based drug leads.

Desotamides A, a cyclohexapeptide produced by the deep-sea-derived Streptomyces scopuliridis SCSIO ZJ46, displays notable antibacterial activities against strains of Streptococcus pnuemoniae, Staphylococcus aureus, and methicillin-resistant Staphylococcus epidermidis (MRSE). In this study, to further explore its antibacterial potential and reveal the antibacterial structure-activity relationship of desotamides, 13 cyclopeptides including 10 new synthetic desotamide A analogues and wollamides B/B1/B2 were synthesized and evaluated for their antibacterial activities against a panel of Gram-positive and -negative pathogens. The bioactivity data reveal that residues at position II and VI greatly impact antibacterial activity. The most potent antibacterial analogues are desotamide A4 (13) and A6 (15) where l-allo-Ile at position II was substituted with l-Ile and Gly at position VI was simultaneously replaced by d-Lys or d-Arg; desotamides A4 (13) and A6 (15) showed a 2–4-fold increase of antibacterial activities against a series of Gram-positive pathogens including the prevalent clinical drug-resistant pathogen methicillin-resistant Staphylococcus aureus (MRSA) with MIC values of 8–32 μg/mL compared to the original desotamide A. The enhanced antibacterial activity, broad antibacterial spectrum of desotamides A4 and A6 highlighted their potential as new antibiotic leads for further development.

Two new C-glycoside angucyclines, marangucycline A (1) and marangucycline B (2), along with three known compounds, dehydroxyaquayamycin (3), undecylprodigiosin (4) and metacycloprodigiosin (5), have been identified as products of the deep-sea sediment strain Streptomyces sp. SCSIO 11594. New structures were elucidated on the basis of HRESIMS, 1D and 2D NMR analyses and comparisons to previously reported datasets. Compounds 2 and 4 displayed in vitro cytotoxicity against four cancer cell lines A594, CNE2, HepG2, MCF-7 superior to those obtained with cisplatin, the positive control. Notably, compound 2 bearing a keto-sugar displayed significant cytotoxicity against cancer cell lines with IC50 values ranging from 0.24 to 0.56 μM; An IC50 value of 3.67 μM was found when using non-cancerous hepatic cell line HL7702, demonstrating the cancer cell selectivity of 2. Compounds 1–3 were proved to have weak antibacterial activities against Enterococcus faecalis ATCC29212 with an MIC value of 64.0 μg/mL. Moreover, 3 displayed selective antibacterial activity against methicillin-resistant Staphylococcus epidermidis shhs-E1 with an MIC value of 16.0 μg/mL.

Three new eremophilane sesquiterpenes (1–3) were isolated from the mangrove endophytic fungus Xylaria sp. BL321 together with 07H239-A (4), a known analogue of the new compounds. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. Compound 4 showed activation activity on α-glucosidase at 0.15 μM (146%), and then, 4 gradually produced inhibitory activity on α-glucosidase with increasing concentration, and the IC50 value is 6.54 μM.

Esophageal squamous cell carcinoma (ESCC) is a kind of malignant tumor with high incidence and mortality in the digestive system. The aim of this study is to explore the function of lnc-ABCA12-3 in the development of ESCC and its unique mechanisms. RT-PCR was applied to detect gene transcription levels in tissues or cell lines like TE-1, EC9706, and HEEC cells. Western blot was conducted to identify protein expression levels of mitochondrial apoptosis and toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) signaling pathway. CCK-8 and EdU assays were carried out to measure cell proliferation, and cell apoptosis was examined by flow cytometry. ELISA was used for checking the changes in glycolysis-related indicators. Lnc-ABCA12-3 was highly expressed in ESCC tissues and cells, which preferred it to be a candidate target. The TE-1 and EC9706 cells proliferation and glycolysis were obviously inhibited with the downregulation of lnc-ABCA12-3, while apoptosis was promoted. TLR4 activator could largely reverse the apoptosis acceleration and relieved the proliferation and glycolysis suppression caused by lnc-ABCA12-3 downregulation. Moreover, the effect of lnc-ABCA12-3 on ESCC cells was actualized by activating the TLR4/NF-κB signaling pathway under the mediation of exosome. Taken together, the lnc-ABCA12-3 could promote the proliferation and glycolysis of ESCC, while repressing its apoptosis probably by regulating the TLR4/NF-κB signaling pathway under the mediation of exosome. [ABSTRACT FROM AUTHOR]

Galactose, a monosaccharide capable of assuming two possible configurational isomers (d-/l-), can exist as a six-membered ring, galactopyranose (Galp), or as a five-membered ring, galactofuranose (Galf). UDP-galactopyranose mutase (UGM) mediates the conversion of pyranose to furanose thereby providing a precursor for d-Galf. Moreover, UGM is critical to the virulence of numerous eukaryotic and prokaryotic human pathogens and thus represents an excellent antimicrobial drug target. However, the biosynthetic mechanism and relevant enzymes that drive l-Galf production have not yet been characterized. Herein we report that efforts to decipher the sugar biosynthetic pathway and tailoring steps en route to nucleoside antibiotic A201A led to the discovery of a GDP-l-galactose mutase, MtdL. Systematic inactivation of 18 of the 33 biosynthetic genes in the A201A cluster and elucidation of 10 congeners, coupled with feeding and in vitro biochemical experiments, enabled us to: (i) decipher the unique enzyme, GDP-l-galactose mutase associated with production of two unique d-mannose-derived sugars, and (ii) assign two glycosyltransferases, four methyltransferases, and one desaturase that regiospecifically tailor the A201A scaffold and display relaxed substrate specificities. Taken together, these data provide important insight into the origin of l-Galf-containing natural product biosynthetic pathways with likely ramifications in other organisms and possible antimicrobial drug targeting strategies. [ABSTRACT FROM AUTHOR]

Three new eremophilane sesquiterpenes (1-3) were isolated from the mangrove endophytic fungus Xylaria sp. BL321 together with 07H239-A (4), a known analogue of the new compounds. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. Compound 4 showed activation activity on α-glucosidase at 0.15 µM (146%), and then, 4 gradually produced inhibitory activity on α-glucosidase with increasing concentration, and the IC50 value is 6.54 µM. [ABSTRACT FROM AUTHOR]

McbA was characterized in vitro as a novel amide synthetase in the marinacarbolines A-D biosynthetic pathway, catalyzing amide bond formation between 1-acetyl-3-carboxy-β-carboline (1a) and substituted-β-phenethylamines (1b, 2b, 3b) and tryptamine (4b) in an ATP-dependent manner. Enzyme kinetic analyses highlight β-phenethylamine as the most suitable amine donor. McbA showed broad substrate compatibility with substituted amines; 10 new β-carboline analogues were chemoenzymatically generated. [ABSTRACT FROM AUTHOR]