title: Multiple posttranscriptional regulatory mechanisms partner to control ethanolamine utilization in Enterococcus faecalis.
abstract: Ethanolamine, a product of the breakdown of phosphatidylethanolamine from cell membranes, is abundant in the human intestinal tract and in processed foods. Effective utilization of ethanolamine as a carbon and nitrogen source may provide a survival advantage to bacteria that inhabit the gastrointestinal tract and may influence the virulence of pathogens. In this work, we describe a unique series of posttranscriptional regulatory strategies that influence expression of ethanolamine utilization genes (eut) in Enterococcus, Clostridium, and Listeria species. One of these mechanisms requires an unusual 2-component regulatory system. Regulation involves specific sensing of ethanolamine by a sensor histidine kinase (EutW), resulting in autophosphorylation and subsequent phosphoryl transfer to a response regulator (EutV) containing a RNA-binding domain. Our data suggests that EutV is likely to affect downstream gene expression by interacting with conserved transcription termination signals located within the eut locus. Breakdown of ethanolamine requires adenosylcobalamin (AdoCbl) as a cofactor, and, intriguingly, we also identify an intercistronic AdoCbl riboswitch that has a predicted structure different from previously established AdoCbl riboswitches. We demonstrate that association of AdoCbl to this riboswitch prevents formation of an intrinsic transcription terminator element located within the intercistronic region. Together, these results suggest an intricate and carefully coordinated interplay of multiple regulatory strategies for control of ethanolamine utilization genes. Gene expression appears to be directed by overlapping posttranscriptional regulatory mechanisms, each responding to a particular metabolic signal, conceptually akin to regulation by multiple DNA-binding transcription factors.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, TX 77030, USA.
authors.forename: Kristina A
authors.initials: KA
authors.lastname: Fox
authors.forename: Arati
authors.initials: A
authors.lastname: Ramesh
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Stearns
authors.forename: Agathe
authors.initials: A
authors.lastname: Bourgogne
authors.forename: Angelica
authors.initials: A
authors.lastname: Reyes-Jara
authors.forename: Wade C
authors.initials: WC
authors.lastname: Winkler
authors.forename: Danielle A
authors.initials: DA
authors.lastname: Garsin
mesh_terms: D001426:Bacterial Proteins; D003013:Clostridium; D016983:Enterococcus; D013293:Enterococcus faecalis / Q000378:metabolism; D019856:Ethanolamine / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D006801:Humans; D008087:Listeria; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D011494:Protein Kinases / Q000502:physiology; D014157:Transcription Factors
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors; D019856:Ethanolamine; D011494:Protein Kinases; D000071677:Histidine Kinase