LuxT Is a Global Regulator of Low-Cell-Density Behaviors, Including Type III Secretion, Siderophore Production, and Aerolysin Production, in Vibrio harveyi.

TitleLuxT Is a Global Regulator of Low-Cell-Density Behaviors, Including Type III Secretion, Siderophore Production, and Aerolysin Production, in Vibrio harveyi.
Publication TypeJournal Article
Year of Publication2022
AuthorsEickhoff, MJ, Fei, C, Cong, J-P, Bassler, BL
JournalmBio
Paginatione0362121
Date Published2022 Jan 18
ISSN2150-7511
Abstract

<p>Quorum sensing (QS) is a chemical communication process in which bacteria produce, release, and detect extracellular signaling molecules called autoinducers. Via combined transcriptional and posttranscriptional regulatory mechanisms, QS allows bacteria to collectively alter gene expression on a population-wide scale. Recently, the TetR family transcriptional regulator LuxT was shown to control Vibrio harveyi 1, encoding the Qrr1 small RNA that functions at the core of the QS regulatory cascade. Here, we use RNA sequencing to reveal that, beyond the control of 1, LuxT is a global regulator of 414 V. harveyi genes, including those involved in type III secretion, siderophore production, and aerolysin toxin biosynthesis. Importantly, LuxT directly represses , encoding a GntR family transcriptional regulator, and LuxT control of type III secretion, siderophore, and aerolysin genes occurs by two mechanisms, one that is SwrZ dependent and one that is SwrZ independent. All of these target genes specify QS-controlled behaviors that are enacted when V. harveyi is at low cell density. Thus, LuxT and SwrZ function in parallel with QS to drive particular low-cell-density behaviors. Phylogenetic analyses reveal that is highly conserved among , but is less well conserved. In a test case, we find that in Aliivibrio fischeri, LuxT also represses . SwrZ is a repressor of A. fischeri siderophore production genes. Thus, LuxT repression of drives the activation of A. fischeri siderophore gene expression. Our results indicate that LuxT is a major regulator among , and in the species that also possess , LuxT functions with SwrZ to control gene expression. Bacteria precisely tune gene expression patterns to successfully react to changes that occur in the environment. Defining the mechanisms that enable bacteria to thrive in diverse and fluctuating habitats, including in host organisms, is crucial for a deep understanding of the microbial world and also for the development of effective applications to promote or combat particular bacteria. In this study, we show that a regulator called LuxT controls over 400 genes in the marine bacterium Vibrio harveyi and that LuxT is highly conserved among species, ubiquitous marine bacteria that often cause disease. We characterize the mechanisms by which LuxT controls genes involved in virulence and nutrient acquisition. We show that LuxT functions in parallel with a set of regulators of the bacterial cell-to-cell communication process called quorum sensing to promote V. harveyi behaviors at low cell density.</p>

DOI10.1128/mbio.03621-21
Alternate JournalmBio
PubMed ID35038896
PubMed Central IDPMC8764538
Grant ListR37 GM065859 / GM / NIGMS NIH HHS / United States
T32 GM007388 / GM / NIGMS NIH HHS / United States