Browsing by Author "Zhong, Guangming"

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    Advances and Obstacles in the Genetic Dissection of Chlamydial Virulence
    (Springer, 2018) Brothwell, Julie A.; Muramatsu, Matthew K.; Zhong, Guangming; Nelson, David E.; Microbiology and Immunology, School of Medicine
    Obligate intracellular pathogens in the family Chlamydiaceae infect taxonomically diverse eukaryotes ranging from amoebae to mammals. However, many fundamental aspects of chlamydial cell biology and pathogenesis remain poorly understood. Genetic dissection of chlamydial biology has historically been hampered by a lack of genetic tools. Exploitation of the ability of chlamydia to recombine genomic material by lateral gene transfer (LGT) ushered in a new era in chlamydia research. With methods to map mutations in place, genetic screens were able to assign functions and phenotypes to specific chlamydial genes. Development of an approach for stable transformation of chlamydia also provided a mechanism for gene delivery and platforms for disrupting chromosomal genes. Here, we explore how these and other tools have been used to test hypotheses concerning the functions of known chlamydial virulence factors and discover the functions of completely uncharacterized genes. Refinement and extension of the existing genetic tools to additional Chlamydia spp. will substantially advance understanding of the biology and pathogenesis of this important group of pathogens.
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    Tail-specific protease is an essential Chlamydia virulence factor that mediates the differentiation of elementary bodies into reticulate bodies
    (American Society for Microbiology, 2024) Banerjee, Arkaprabha; Jacobs, Kaylee R.; Wang, Yihui; Doud, Emma H.; Toh, Evelyn; Stein, Barry D.; Mosley, Amber L.; Zhong, Guangming; Morrison, Richard P.; Morrison, Sandra G.; Hu, Shuai; Brothwell, Julie A.; Nelson, David E.; Microbiology and Immunology, School of Medicine
    Tail-specific proteases (Tsp) are members of a widely distributed family of serine proteases that commonly target and process periplasmic proteins in Gram-negative bacteria. The obligately intracellular, Gram-negative Chlamydia encode a highly conserved Tsp homolog whose target and function are unclear. We identified a Chlamydia muridarum mutant with a nonsense mutation in tsp. Differentiation of the tsp mutant elementary bodies into vegetative reticulate bodies was delayed at 37°C and completely blocked at 40°C. Tsp localized to C. muridarum cells but was not detected outside the inclusion, suggesting that it targets chlamydial rather than host proteins. The abundance of key chlamydia outer membrane complex and virulence-related proteins differed in wild-type and tsp mutant elementary bodies, consistent with the possibility that Tsp regulates developmental cycle progression. The altered abundances of chlamydial structural and virulence factors could explain why the mutant, but not an isogenic recombinant with wild-type tsp, was highly attenuated in a mouse intravaginal infection model. Thus, chlamydial Tsp is required for timely differentiation of elementary bodies into reticulate bodies in vitro and is an essential virulence factor in vivo.