title: Message from a human gut symbiont: sensitivity is a prerequisite for sharing.
abstract: Microbial genome sequencing projects are beginning to provide insights about the molecular foundations of human-bacterial symbioses. The intestine contains our largest collection of symbionts, where members of Bacteroides comprise approximately 25% of the microbiota in adults. The recently defined proteome of a prominent human intestinal symbiont, Bacteroides thetaiotaomicron, contains an elaborate environmental-sensing apparatus. This apparatus includes an unprecedented number of extracytoplasmic function (ECF) sigma-factors, and a large collection of novel hybrid two-component systems composed of membrane-spanning periplasmic proteins with histidine kinase, phosphoacceptor, response regulator receiver and DNA-binding domains. These sensors are linked to the organism's large repertoire of genes involved in acquiring and processing dietary polysaccharides ('the glycobiome'). This arrangement illustrates how a successful symbiont has evolved strategies for detecting and responding to conditions in its niche so that it can sustain beneficial relationships with its microbial and human partners.
authors.affiliation: Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Xu
authors.forename: Herbert C
authors.initials: HC
authors.lastname: Chiang
authors.forename: Magnus K
authors.initials: MK
authors.lastname: Bjursell
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Gordon
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001439:Bacteroides / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007422:Intestines / Q000382:microbiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D012808:Sigma Factor / Q000378:metabolism; D015398:Signal Transduction; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor