BibTex format
@phdthesis{Zhang:2025,
author = {Zhang, B},
title = {Structural studies on bacterial enhancer binding proteins HrpR-HrpS and their regulations during sigma-54 dependent bacterial transcription initiation},
year = {2025}
}
RIS format (EndNote, RefMan)
TY - THES
AB - Transcription is the process of unwinding double stranded DNA (dsDNA) and using one strand as template to make copies of RNA polymers. Transcription requires a protein complex called RNA polymerase (RNAP). Transcription initiation requires RNAP to be located correctly on DNA. In bacteria, this is done by factors, which recognise specific regions called promoter and create the initial opening on the hydrogen bonded dsDNA to allow transcription to begin. A special member of sigma family 54 is able to recruit RNAP to the promoter, however, does not spontaneously initiate transcription. Instead, it requires additional activators called bacterial enhancer binding proteins (bEBPs) which bind DNA remotely upstream. By DNA looping, bEBPs interact with 54 downstream to facilitate the initial opening of dsDNA, subsequently activating transcription. bEBP-mediated transcription is extensively regulated to allow specific genes expression in response to signals such as host infection, stress response, starvation. In plant pathogen Pseudomonas syringae, genes associated with host infection are activated by HrpR and HrpS, bEBPs that uniquely function as heterohexamer upon activation. Their bEBP functions are found to be inhibited by HrpV and activated by HrpG, through unknown mechanism. Using cryo-EM, we characterised the structure of HrpRS in complex with promoter DNA, explaining the sequence-specific interaction by bEBP and the underlying roles of upstream DNA in promoting hexamer assembly and 54 interaction. Our models also provide insights into the selective advantages of heterohexameric arrangement over other bEBPs. Lastly, we presented data characterising the HrpV inhibition and the HrpG activation, explaining the underlying mechanisms in regulating bacterial pathogenesis.
AU - Zhang,B
PY - 2025///
TI - Structural studies on bacterial enhancer binding proteins HrpR-HrpS and their regulations during sigma-54 dependent bacterial transcription initiation
ER -