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zhou, m.

Publications and source records attributed to zhou, m..

3 recordsLinked to original sources
bioRxiv2021

Molecular Epidemiology and Microbiological Characteristics of Cryptococcus gattii VGII isolates from China

Cryptococcus gattii (C. gattii) is a fungal pathogen that once caused an outbreak of cryptococcosis on Vancouver Island, and had spread worldwide, while few data were available in China. In this study, seven clinical isolates of C. gattii VGII were collected from 19 hospitals, Multi-locus Sequence Typing (MLST) analysis and whole-genome sequencing (WGS) was performed, and combined with published data for phylogenetic analysis. In addition, in vitro antifungal susceptibility testing, phenotypic analysis, and in vivo virulence studies were performed, subsequently, histopathological analysis of lung tissue was performed. C.gattii VGII infected patients were mainly immunocompetent male, and most of them had symptoms of central nervous system (CNS) involvement. MLST results showed that isolates from china exhibited high genetic diversity, and sequence type (ST) 7 was the major ST among the isolates. Some clinical isolates showed a close phylogenetic relationship with strains from Australia and South America. All clinical isolates did not show resistance to antifungal drugs. In addition, there was no correlation between virulence factors (temperature, melanin production, and capsule size) and virulence while in vivo experiments showed significant differences in virulence among strains. Lung fungal burden and damage to lung tissue correlated with virulence, and degree of damage to lung tissue in mice may highlight differences in virulence. Our work seeks to provide useful data for molecular epidemiology, antifungal susceptibility, and virulence differences of C. gattii VGII in China. Author SummaryCryptococcus gattii is one of the life-threatening fungal pathogens that can infect immunocompetent individuals. C.gattii can be invaded through the respiratory tract and can be spread to the brain, causing meningoencephalitis and even death. In 1999, an outbreak of C. gattii VGII occurred on Vancouver Island in Canada and spread in the Pacific Northwest region, which attracted more attention. Compared with other nations, the data of C gattii VGII in China was limited. To better understand the molecular epidemiology and microbiological characteristics of C.gattii VGII isolates from China, Bioinformatics analysis and in vivo and in vitro experiments were performed for clinical strains. Multi-locus Sequence Typing and whole-genome sequencing reveal the genetic diversity of the isolates and genetic relationships with isolates from other countries. We also investigated the antifungal drug susceptibility and virulence differences of the isolates. The authors expect that our work can provide useful data for the prevention and control of C. gattii VGII in China and to draw attention to C. gattii.

microbiology↗
bioRxiv2021

DNA sliding and loop formation by E. coli SMC complex: MukBEF

SMC (structural maintenance of chromosomes) complexes share conserved architectures and function in chromosome maintenance via an unknown mechanism. Here we have used single-molecule techniques to study MukBEF, the SMC complex in Escherichia coli. Real-time movies show MukB alone can compact DNA and ATP inhibits DNA compaction by MukB. We observed that DNA unidirectionally slides through MukB, potentially by a ratchet mechanism, and the sliding speed depends on the elastic energy stored in the DNA. MukE, MukF and ATP binding stabilize MukB and DNA interaction, and ATP hydrolysis regulates the loading/unloading of MukBEF from DNA. Our data suggests a new model for how MukBEF organizes the bacterial chromosome in vivo; and this model will be relevant for other SMC proteins.

biophysics↗
bioRxiv2021

Competitive binding of MatP and topoisomerase IV to the MukB dimerization hinge

SMC complexes have ubiquitous roles in chromosome organisation. In Escherichia coli, the interplay between the SMC complex, MukBEF, and matS-bound MatP in the replication termination region, ter, results in depletion of MukBEF from ter, thus promoting chromosome individualisation by directing replichores to separate cell halves. MukBEF also interacts with topoisomerase IV ParC2E2 heterotetramers, to direct its chromosomal distribution to mirror that of MukBEF, thereby facilitating coordination between chromosome organisation and decatenation by topoisomerase IV. Here we demonstrate that the MukB dimerization hinge binds ParC and MatP with the same dimer to dimer stoichiometry. MatP and ParC have an overlapping binding interface on the MukB hinge, leading to their mutually exclusive binding. Furthermore, the MukB hinge fails to stably associate with matS-bound MatP, while MatP mutants deficient in matS binding are impaired in MukB hinge binding, demonstrating that mats competes with the hinge for MatP binding. Cells expressing MukBEF complexes containing a mutation in the MukB hinge interface for ParC/MatP binding are deficient in ParC binding in vivo, despite having a Muk+ topoisomerase IV+ phenotype. This mutant protein is also impaired in MatP binding in vitro, and cells expressing this variant exhibit a MukBEF cellular localisation consistent with impaired MatP binding.

biochemistry↗