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Article
Global H-NS counter-silencing by LuxR activates quorum sensing gene expression
Nucleic Acids Research
  • Ryan R. Chaparian, Indiana University Bloomington
  • Minh L.N. Tran, San Jose State University
  • Laura C. Miller Conrad, San Jose State University
  • Douglas B. Rusch, Indiana University Bloomington
  • Julia C. Van Kessel, Indiana University Bloomington
Publication Date
1-10-2020
Document Type
Article
DOI
10.1093/nar/gkz1089
Abstract

Bacteria coordinate cellular behaviors using a cell-cell communication system termed quorum sensing. In Vibrio harveyi, the master quorum sensing transcription factor LuxR directly regulates >100 genes in response to changes in population density. Here, we show that LuxR derepresses quorum sensing loci by competing with H-NS, a global transcriptional repressor that oligomerizes on DNA to form filaments and bridges. We first identified H-NS as a repressor of bioluminescence gene expression, for which LuxR is a required activator. In an hns deletion strain, LuxR is no longer necessary for transcription activation of the bioluminescence genes, suggesting that the primary role of LuxR is to displace H-NS to derepress gene expression. Using RNA-seq and ChIP-seq, we determined that H-NS and LuxR co-regulate and co-occupy 28 promoters driving expression of 63 genes across the genome. ChIP-PCR assays show that as autoinducer concentration increases, LuxR protein accumulates at co-occupied promoters while H-NS protein disperses. LuxR is sufficient to evict H-NS from promoter DNA in vitro, which is dependent on LuxR DNA binding activity. From these findings, we propose a model in which LuxR serves as a counter-silencer at H-NS-repressed quorum sensing loci by disrupting H-NS nucleoprotein complexes that block transcription.

Funding Number
DUE-1258366
Funding Sponsor
National Science Foundation
Comments

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Creative Commons License
Creative Commons Attribution-Noncommercial 4.0
Citation Information
Ryan R. Chaparian, Minh L.N. Tran, Laura C. Miller Conrad, Douglas B. Rusch, et al.. "Global H-NS counter-silencing by LuxR activates quorum sensing gene expression" Nucleic Acids Research Vol. 48 Iss. 1 (2020) p. 171 - 183
Available at: http://works.bepress.com/laura_millerconrad/10/