Biomedical subjects

Jennifer M Henke

Publications and source records attributed to Jennifer M Henke.

3 recordsLinked to original sources

PubMed2004

Bacterial social engagements.

Quorum sensing is a process that enables bacteria to communicate using secreted signaling molecules called autoinducers. This process enables a population of bacteria to regulate gene expression collectively and, therefore, control behavior on a community-wide scale. Quorum sensing is widespread in the bacterial world and, generally, processes controlled by quorum sensing are unproductive when undertaken by an individual bacterium but become effective when undertaken by the group. Cell-cell communication can occur within and between bacterial species, and between bacteria and their eukaryotic hosts, which suggests that the chemical lexicon is complex. Prokaryotic and eukaryotic mechanisms for enhancing and inhibiting quorum sensing have been identified, which suggests that manipulation of quorum-sensing-controlled processes could be common in bacterial-bacterial and bacterial-eukaryotic associations.

Bacteria↗

PubMed2004

Quorum sensing regulates type III secretion in Vibrio harveyi and Vibrio parahaemolyticus.

In a process known as quorum sensing, bacteria communicate with one another by producing, releasing, detecting, and responding to signal molecules called autoinducers. Vibrio harveyi, a marine pathogen, uses two parallel quorum-sensing circuits, each consisting of an autoinducer-sensor pair, to control the expression of genes required for bioluminescence and a number of other target genes. Genetic screens designed to discover autoinducer-regulated targets in V. harveyi have revealed genes encoding components of a putative type III secretion (TTS) system. Using transcriptional reporter fusions and TTS protein localization studies, we show that the TTS system is indeed functional in V. harveyi and that expression of the genes encoding the secretion machinery requires an intact quorum-sensing signal transduction cascade. The newly completed genome of the closely related marine bacterium Vibrio parahaemolyticus, which is a human pathogen, shows that it possesses the genes encoding both of the V. harveyi-like quorum-sensing signaling circuits and that it also has a TTS system similar to that of V. harveyi. We show that quorum sensing regulates TTS in V. parahaemolyticus. Previous reports connecting quorum sensing to TTS in enterohemorrhagic and enteropathogenic Escherichia coli show that quorum sensing activates TTS at high cell density. Surprisingly, we find that at high cell density (in the presence of autoinducers), quorum sensing represses TTS in V. harveyi and V. parahaemolyticus.

4-Butyrolactone↗

PubMed2004

Three parallel quorum-sensing systems regulate gene expression in Vibrio harveyi.

In a process called quorum sensing, bacteria communicate using extracellular signal molecules termed autoinducers. Two parallel quorum-sensing systems have been identified in the marine bacterium Vibrio harveyi. System 1 consists of the LuxM-dependent autoinducer HAI-1 and the HAI-1 sensor, LuxN. System 2 consists of the LuxS-dependent autoinducer AI-2 and the AI-2 detector, LuxPQ. The related bacterium, Vibrio cholerae, a human pathogen, possesses System 2 (LuxS, AI-2, and LuxPQ) but does not have obvious homologues of V. harveyi System 1. Rather, System 1 of V. cholerae is made up of the CqsA-dependent autoinducer CAI-1 and a sensor called CqsS. Using a V. cholerae CAI-1 reporter strain we show that many other marine bacteria, including V. harveyi, produce CAI-1 activity. Genetic analysis of V. harveyi reveals cqsA and cqsS, and phenotypic analysis of V. harveyi cqsA and cqsS mutants shows that these functions comprise a third V. harveyi quorum-sensing system that acts in parallel to Systems 1 and 2. Together these communication systems act as a three-way coincidence detector in the regulation of a variety of genes, including those responsible for bioluminescence, type III secretion, and metalloprotease production.

4-Butyrolactone↗