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Gram-positive bacteria experience considerable mechanical perturbation when adhering to host surfaces during colonization and infection. They have evolved various adhesion proteins that are mechanically robust to ensure strong surface adhesion. Recently, it was discovered that these adhesion proteins contain rare, extra intramolecular covalent bonds that stabilize protein structures and participate in surface bonding. These intramolecular covalent bonds include isopeptides, thioesters, and ester bonds, which often form spontaneously without the need for additional enzymes. With the development of single-molecule force spectroscopy techniques, the detailed mechanical roles of these intramolecular covalent bonds have been revealed. In this review, we summarize the recent advances in this area of research, focusing on the link between the mechanical stability and function of these covalent bonds in Gram-positive bacterial surface proteins. We also highlight the potential impact of these discoveries on the development of novel antibiotics and chemical biology tools.

Biological load-bearing tissues are strong, tough, and recoverable under periodic mechanical loads. However, such features have rarely been achieved simultaneously in the same synthetic hydrogels. Here, we use a force-coupled enzymatic reaction to tune a strong covalent peptide linkage to a reversible bond. Based on this concept we engineered double network hydrogels that combine high mechanical strength and reversible mechanical recovery in the same hydrogels. Specifically, we found that a peptide ligase, sortase A, can promote the proteolysis of peptides under force. The peptide bond can be re-ligated by the same enzyme in the absence of force. This allows the sacrificial network in the double-network hydrogels to be ruptured and rebuilt reversibly. Our results demonstrate a general approach for precisely controlling the mechanical and dynamic properties of hydrogels at the molecular level.

Objective To assess the clinical outcomes of open calcaneal fractures with medial wounds treated with one‐stage management, including early modern wound care, sequential reduction, and frame structure fixation using percutaneous Kirschner wires. Methods A total of 19 patients with open calcaneal fractures admitted to our hospital from May 2016 to March 2019 were selected in this study. Twelve type‐II and seven type‐IIIA medial open injuries were identified according to the classification of Gustilo and Anderson. Fractures were stratified by Sanders classification, including nine type‐II fractures, seven type‐III fractures, and three type‐IV fractures. All patients accepted one‐stage irrigation and debridement, sequential reduction of calcaneal fractures through the open medial wound, percutaneous Kirschner wire fixation, and primary closure of wounds covered with vacuum‐assisted closure (VAC) device. The Bohler angle, the Gissane angle, and the width of the calcaneus were compared before and after surgery. The functional results were evaluated according to the Paley and Hall score system, visual analogue scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot score, Maryland Foot Score, and related complications. Results The follow‐up duration for all patients ranged from 14 to 28 months (mean, 22.7 months). The angle of Bohler and Giasane was increased from (−7.6° ± 15.0°) and (96.6° ± 7.6°) before surgery to (23.7° ± 6.1°) and (124.1° ± 7.1°) postoperatively (P, Open calcaneus fractures with medial wound is treated by one‐stage sequential reduction and frame structure fixation using percutaneous Kirschner wires. This technique allows direct restoration of calcaneal morphology with a minimal invasion of soft tissues at an early stage.

Real-time tracking of multiple particles is key for quantitative analysis of dynamic biophysical processes and materials science via time-lapse microscopy image data, especially for single molecule biophysical techniques, such as magnetic tweezers and centrifugal force microscopy. However, real-time multiple particle tracking with high resolution is limited by the current imaging processes or tracking algorithms. Here, we demonstrate 1 nm resolution in three dimensions in real-time with a graphics-processing unit (GPU) based on a compute unified device architecture (CUDA) parallel computing framework instead of only a central processing unit (CPU). We also explore the trade-offs between processing speed and size of the utilized regions of interest and a maximum speedup of 137 is achieved with the GPU compared with the CPU. Moreover, we utilize this method with our recently self-built centrifugal force microscope (CFM) in experiments that track multiple DNA-tethered particles. Our approach paves the way for high-throughput single molecule techniques with high resolution and efficiency. LAY DESCRIPTION: Particles are widely used as probes in life sciences through their motions. In single molecule techniques such as optical tweezers and magnetic tweezers, microbeads are used to study intermolecular or intramolecular interactions via beads tracking. Also tracking multiple beads' motions could study cell-cell or cell-ECM interactions in traction force microscopy. Therefore, particle tracking is of key important during these researches. However, parallel 3D multiple particle tracking in real-time with high resolution is a challenge either due to the algorithm or the program. Here, we combine the performance of CPU and CUDA-based GPU to make a hybrid implementation for particle tracking. In this way, a speedup of 137 is obtained compared the program before only with CPU without loss of accuracy. Moreover, we improve and build a new centrifugal force microscope for multiple single molecule force spectroscopy research in parallel. Then we employed our program into centrifugal force microscope for DNA stretching study. Our results not only demonstrate the application of this program in single molecule techniques, also indicate the capability of multiple single molecule study with centrifugal force microscopy.

Strain S150 was isolated from the tobacco rhizosphere as a plant growth‐promoting rhizobacterium. It increased plant fresh weight significantly and lateral root development, and it antagonized plant pathogenic fungi but not phytobacteria. Further tests showed that strain S150 solubilized organic phosphate and produced ammonia, siderophore, protease, amylase, and cellulase, but it did not produce indole‐3‐acetic acid. Using morphology, physiological characteristics, and multi‐locus sequence analysis, strain S150 was identified as Pseudomonas koreensis. The complete genome of strain S150 was sequenced, and it showed a single circular chromosome of 6,304,843 bp with a 61.09% G + C content. The bacterial genome contained 5,454 predicted genes that occupied 87.7% of the genome. Venn diagrams of the identified orthologous clusters of P. koreensis S150 with the other three sequenced P. koreensis strains revealed up to 4,167 homologous gene clusters that were shared among them, and 21 orthologous clusters were only present in the genome of strain S150. Genome mining of the bacterium P. koreensis S150 showed that the strain possessed 10 biosynthetic gene clusters for secondary metabolites, which included four clusters of non‐ribosomal peptide synthetases (NRPSs) involved in the biosynthesis of cyclic lipopeptides (CLPs). One of the NRPSs possibly encoded lokisin, a cyclic lipopeptide produced by fluorescent Pseudomonas. Genomic mutation of the lokA gene, which is one of the three structural NRPS genes for lokisin in strain S150, led to a deficiency in fungal antagonism that could be restored fully by gene complementation. The results suggested that P. koreensis S150 is a novel plant growth‐promoting agent with specific cyclic lipopeptides and contains a lokisin‐encoding gene cluster that is dominant against plant fungal pathogens., We reported a newly isolated Pseudomonas koreensis strain S150, which antagonized plant pathogens, solubilized phosphates, produced siderophores and enzymes, and promoted plant growth. Genome mining showed that the strain S150 possesses 10 genomic islands coding for secondary metabolites, one of which is lokisin, an unusual cyclic lipopeptide. We generated a deletion mutant for the smallest non‐ribosomal peptide synthetase gene lokA in strain S150. Antifungal activity was deficient in the lokA mutant and was restored by gene complementation.

Pseudomonas syringae pv. tomato DC3000 and its derivatives cause disease in tomato, Arabidopsis and Nicotiana benthamiana. The primary virulence factors include a repertoire of 29 effector proteins injected into plant cells by the type III secretion system and the phytotoxin coronatine. The complete repertoire of effector genes and key coronatine biosynthesis genes have been progressively deleted and minimally reassembled to reconstitute basic pathogenic ability in N. benthamiana, and in Arabidopsis plants that have mutations in target genes that mimic effector actions. This approach and molecular studies of effector activities and plant immune system targets have highlighted a small subset of effectors that contribute to essential processes in pathogenesis. Most notably, HopM1 and AvrE1 redundantly promote an aqueous apoplastic environment, and AvrPtoB and AvrPto redundantly block early immune responses, two conditions that are sufficient for substantial bacterial growth in planta. In addition, disarmed DC3000 polymutants have been used to identify the individual effectors responsible for specific activities of the complete repertoire and to more effectively study effector domains, effector interplay and effector actions on host targets. Such work has revealed that AvrPtoB suppresses cell death elicitation in N. benthamiana that is triggered by another effector in the DC3000 repertoire, highlighting an important aspect of effector interplay in native repertoires. Disarmed DC3000 polymutants support the natural delivery of test effectors and infection readouts that more accurately reveal effector functions in key pathogenesis processes, and enable the identification of effectors with similar activities from a broad range of other pathogens that also defeat plants with cytoplasmic effectors.

Nitric oxide (NO) plays a key role in regulating a wide range of physiological and biochemical processes. This study investigated possible effects of NO, which was supplied by sodium nitroprusside (SNP), NO donor, on selenium (Se) concentration, Se species within roots, activities and gene transcription of selenite uptake, and metabolism-related transporters or enzymes using ICP-MS, HPLC-ICP/MS, qRT-PCR, fluorescence imaging, and biochemical analysis in the roots of rice (Oryza sativa L.) seedling. A suitable SNP concentration (10 µM) increased Se concentration in rice roots. NO enhanced the gene transcription of phosphate transporter OsPT2 and sulfate transporters OsSultr1;2 and OsSultr4;1 that contribute to selenite uptake. Furthermore, NO increased selenocysteine and methyl-selenocysteine concentrations in roots, stimulated glutathione biosynthesis by up-regulating the transcript levels of γ-glutamylcysteine synthetase (γ-ECS) and glutathione synthetase (GS), and increased cysteine synthase (CS) activity. In conclusion, our results indicate that NO promotes Se concentration of rice seedling roots by enhancing selenite uptake, up-regulating gene transcription of selenite uptake-related transporters, and increasing Se metabolism through regulating glutathione biosynthesis.