Biology subjects

Wurihan, W.

Publications and source records attributed to Wurihan, W..

4 recordsLinked to original sources

bioRxiv2026

A Refined Developmental Transcriptomic Landscape Reveals Four Coordinated Programs in Chlamydia trachomatis

The developmental cycle of Chlamydia trachomatis requires coordinated transitions between infectious elementary bodies (EBs) and replicative reticulate bodies (RBs), yet the temporal organization of the underlying transcriptional programs remains incompletely resolved. We performed high-coverage RNA sequencing from 0 to 32 h post-infection (hpi), with closely spaced early sampling, and used unsupervised clustering of temporal expression profiles to identify four coordinated programs: immediate-early host adaptation and developmental program, RB formation and maintenance, RB proliferation and secondary differentiation, and EB formation and invasion. The immediate-early program peaked at 1 hpi and contained a strong representation of inclusion-membrane and intracellular-trafficking genes, together with the developmental regulator gene euo. The RB formation and maintenance program peaked at approximately 3 hpi and sustained expression throughout much of the cycle, encompassing genes that support transcription, translation, and core metabolism. The RB proliferation and secondary differentiation program combined DNA replication and cell-division genes with alternative sigma factors, partner-switching components, and type III secretion apparatus genes, consistent with developmental preparation during proliferation. The EB formation and invasion program contained genes associated with structural maturation, host-cell interaction, and infectious competence. These findings distinguish transient host-adaptation expression from sustained early biosynthetic expression, separate RB establishment from population expansion, and differentiate regulatory preparation for the RB-to-EB transition from later EB maturation. Together, the four programs define partially overlapping transcriptional priorities that provide a framework for investigating how gene expression coordinates chlamydial growth, differentiation, and preparation for the next infection cycle.

microbiology↗

bioRxiv2023

Requirement of GrgA for Chlamydia infectious progeny production, optimal growth, and efficient plasmid maintenance

Chlamydia, an obligate intracellular bacterial pathogen, has a unique developmental cycle involving the differentiation of invading elementary bodies (EBs) to noninfectious reticulate bodies (RBs), replication of RBs, and redifferentiation of RBs into progeny EBs. Progression of this cycle is regulated by three sigma factors, which direct the RNA polymerase to their respective target gene promoters. We hypothesized that the Chlamydia-specific transcriptional regulator GrgA, previously shown to activate {sigma}66 and {sigma}28, plays an essential role in chlamydial development and growth. To test this hypothesis, we applied a novel genetic tool known as dependence on plasmid-mediated expression (DOPE) to create Chlamydia trachomatis with conditional GrgA-deficiency. We show that GrgA-deficient C. trachomatis RBs have a growth rate that is approximately half of the normal rate and fail to transition into progeny EBs. In addition, GrgA-deficient C. trachomatis fail to maintain its virulence plasmid. Results of RNA-seq analysis indicate that GrgA promotes RB growth by optimizing tRNA synthesis and expression of nutrient-acquisition genes, while it enables RB-to-EB conversion by facilitating the expression of a histone and outer membrane proteins required for EB morphogenesis. GrgA also regulates numerous other late genes required for host cell exit and subsequent EB invasion into host cells. Importantly, GrgA stimulates the expression of {sigma}54, the third and last sigma factor, and its activator AtoC, and thereby indirectly upregulating the expression of {sigma}54-dependent genes. In conclusion, our work demonstrates that GrgA is a master transcriptional regulator in Chlamydia and plays multiple essential roles in chlamydial pathogenicity. IMPORTANCEHallmarks of the developmental cycle of the obligate intracellular pathogenic bacterium Chlamydia are the primary differentiation of the infectious elementary body (EB) into the proliferative reticulate body (RB) and the secondary differentiation of RBs back into EBs. The mechanisms regulating these transitions remain unclear. In this report, we developed an effective novel strategy termed DOPE that allows for the knockdown of essential genes in Chlamydia. We demonstrate that GrgA, a Chlamydia-specific transcription factor, is essential for the secondary differentiation and optimal growth of RBs. We also show that GrgA, a chromosome-encoded regulatory protein, controls the maintenance of the chlamydial virulence plasmid. Transcriptomic analysis further indicates that GrgA functions as a critical regulator of all three sigma factors that recognize different promoter sets at developmental stages. The DOPE strategy outlined here should provide a valuable tool for future studies examining chlamydial growth, development, and pathogenicity.

microbiology↗

bioRxiv2023

Requirement of GrgA for Chlamydia infectious progeny production

Hallmarks of the developmental cycle of the obligate intracellular pathogenic bacterium Chlamydia are the primary differentiation of the infectious elementary body (EB) cell type into the proliferative reticulate body (RB) and the secondary differentiation of RBs back into EBs. The detailed mechanisms regulating these transitions are unclear. In this study, we developed a novel strategy termed DOPE (dependence on plasmid-mediated expression) that allows for the knockdown of essential genes in Chlamydia. Importantly, we demonstrate that GrgA, a Chlamydia-specific transcription factor, is essential for the secondary differentiation of RBs into EBs. Our development of a conditional GrgA-deficient chlamydiae should prove valuable for future studies examining chlamydial growth, development, and pathogenicity. Furthermore, because EB formation is absolutely required for chlamydial dissemination within infected individuals, and for chlamydial transmission to new hosts, our maturation-defective chlamydiae system may serve as an attractive attenuated vaccine methodology for the prevention of chlamydial diseases.

microbiology↗

bioRxiv2018

A role for GrgA in regulation of σ28-dependent transcription in the obligate intracellular bacterial pathogen Chlamydia trachomatis

The sexually transmitted obligate intracellular bacterial pathogen Chlamydia trachomatis has a unique developmental cycle consisting of two contrasting cellular forms. Whereas the primary Chlamydia sigma factor, {sigma}66, is involved in the expression of the majority of chlamydial genes throughout the developmental cycle, expression of several late genes requires the alternative sigma factor {sigma}28. In prior work we identified GrgA as a Chlamydia-specific transcription factor that activates {sigma}66-dependent transcription by binding DNA and interacting with a non-conserved region (NCR) of {sigma}66. Here, we extend these findings by showing GrgA can also activate {sigma}28-dependent transcription through direct interaction with {sigma}28. We measure the binding affinity of GrgA for both {sigma}66and {sigma}28, and we identify regions of GrgA important for {sigma}28-dependent transcription. Similar to results obtained with {sigma}66, we find that GrgAs interaction with {sigma}28 involves a NCR located upstream of conserved region 2 of {sigma}28. Our findings suggest GrgA is an important regulator of both {sigma}66- and {sigma}28-dependent transcription in C. trachomatis and further highlight NCRs of bacterial RNA polymerase as targets for regulatory factors unique to particular organisms.

microbiology↗