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Dynemicin is an enediyne natural product from Micromonospora chersina ATCC53710. Access to the biosynthetic gene cluster of dynemicin has enabled the in vitro study of gene products within the cluster to decipher their roles in assembling this unique molecule. This paper reports the crystal structure of DynF, the gene product of one of the genes within the biosynthetic gene cluster of dynemicin. DynF is revealed to be a dimeric eight‐stranded β‐barrel structure with palmitic acid bound within a cavity. The presence of palmitic acid suggests that DynF may be involved in binding the precursor polyene heptaene, which is central to the synthesis of the ten‐membered ring of the enediyne core. [ABSTRACT FROM AUTHOR]

The 1.5 Å resolution crystal structure of DynU16, a protein identified in the dynemicin‐biosynthetic gene cluster, is reported. The structure adopts a di‐domain helix‐grip fold with a uniquely positioned open cavity connecting the domains. The elongated dimensions of the cavity appear to be compatible with the geometry of a linear polyene, suggesting the involvement of DynU16 in the upstream steps of dynemicin biosynthesis. [ABSTRACT FROM AUTHOR]

Natural products and natural product-derived compounds have been widely used for pharmaceuticals for many years, and the search for new natural products that may have interesting activity is ongoing. Abyssomicins are natural product molecules that have antibiotic activity via inhibition of the folate synthesis pathway in microbiota. These compounds also appear to undergo a required [4 + 2] cycloaddition in their biosynthetic pathway. Here we report the structure of an flavin adenine dinucleotide-dependent reductase, AbsH3, from the biosynthetic gene cluster of novel abyssomicins found in Streptomyces sp. LC-6-2. [ABSTRACT FROM AUTHOR]

Summary: Introduction: Azithromycin (AZM) and other macrolide antibiotics are applied as immunomodulatory treatments for CNS disorders. The immunomodulatory and antibiotic properties of AZM are purportedly independent. Aims: To improve the efficacy and reduce antibiotic resistance risk of AZM‐based therapies, we evaluated the immunomodulatory and neuroprotective properties of novel AZM derivatives. We semisynthetically prepared derivatives by altering sugar moieties established as important for inhibiting bacterial protein synthesis. Bone marrow‐derived macrophages (BMDMs) were stimulated in vitro with proinflammatory, M1, stimuli (LPS + INF‐gamma) with and without derivative costimulation. Pro‐ and anti‐inflammatory cytokine production, IL‐12 and IL‐10, respectively, was quantified using ELISA. Neuron culture treatment with BMDM supernatant was used to assess derivative neuroprotective potential. Results: Azithromycin and some derivatives increased IL‐10 and reduced IL‐12 production of M1 macrophages. IL‐10/IL‐12 cytokine shifts closely correlated with the ability of AZM and derivatives to mitigate macrophage neurotoxicity. Conclusions: Sugar moieties that bind bacterial ribosomal complexes can be modified in a manner that retains AZM immunomodulation and neuroprotection. Since the effects of BMDMs in vitro are predictive of CNS macrophage responses, our results open new therapeutic avenues for managing maladaptive CNS inflammation and support utilization of IL‐10/12 cytokine profiles as indicators of macrophage polarization and neurotoxicity. [ABSTRACT FROM AUTHOR]

LipL and Cpr19 are nonheme, mononuclear Fe( II)-dependent, α-ketoglutarate (α KG): UMP oxygenases that catalyze the formation of CO2, succinate, phosphate, and uridine-5′-aldehyde, the last of which is a biosynthetic precursor for several nucleoside antibiotics that inhibit bacterial translocase I (MraY). To better understand the chemistry underlying this unusual oxidative dephosphorylation and establish a mechanistic framework for LipL and Cpr19, we report herein the synthesis of two biochemical probes-[1′,3′,4′,5′,5′-2H] UMP and the phosphonate derivative of UMP-and their activity with both enzymes. The results are consistent with a reaction coordinate that proceeds through the loss of one 2H atom of [1′,3′,4′,5′,5′-2H] UMP and stereospecific hydroxylation geminal to the phosphoester to form a cryptic intermediate, (5′ R)-5′-hydroxy- UMP. Thus, these enzyme catalysts can additionally be assigned as UMP hydroxylase-phospholyases. [ABSTRACT FROM AUTHOR]

A chemoenzymatic platform for the synthesis of S-adenosyl- L-methionine (SAM) analogues compatible with downstream SAM-utilizing enzymes is reported. Forty-four non-native S/Se-alkylated Met analogues were synthesized and applied to probing the substrate specificity of five diverse methionine adenosyltransferases (MATs). Human MAT II was among the most permissive of the MATs analyzed and enabled the chemoenzymatic synthesis of 29 non-native SAM analogues. As a proof of concept for the feasibility of natural product 'alkylrandomization', a small set of differentially-alkylated indolocarbazole analogues was generated by using a coupled hMAT2-RebM system (RebM is the sugar C4′- O-methyltransferase that is involved in rebeccamycin biosynthesis). The ability to couple SAM synthesis and utilization in a single vessel circumvents issues associated with the rapid decomposition of SAM analogues and thereby opens the door for the further interrogation of a wide range of SAM utilizing enzymes. [ABSTRACT FROM AUTHOR]

Rise and shine: Using a gene‐targeting approach aimed at identifying potential L‐threonine:uridine‐5′‐transaldolases that catalyze the formation of (5′S,6′S)‐C‐glycyluridine, a new bacterial translocase I inhibitor was discovered from an actinomycete following fermentation optimization. [ABSTRACT FROM AUTHOR]

QueF (MW = 19.4 kDa) is a recently characterized nitrile oxidoreductase which catalyzes the NADPH-dependent reduction of 7-cyano-7-deazaguanine (preQ0) to 7-aminomethyl-7-deazaguanine, a late step in the biosynthesis of the modified tRNA nucleoside queuosine. Initial crystals of homododecameric Bacillus subtilis QueF diffracted poorly to 8.0 Å. A three-dimensional model based on homology with the tunnel-fold enzyme GTP cyclohydrolase I suggested catalysis at intersubunit interfaces and a potential role for substrate binding in quaternary structure stabilization. Guided by this insight, a second crystal form was grown that was strictly dependent on the presence of preQ0. This crystal form diffracted to 2.25 A resolution. [ABSTRACT FROM AUTHOR]

Review: 147 refs. [ABSTRACT FROM AUTHOR]