title: Homocysteine thiolactone is a positive effector of sigma(S) levels in Escherichia coli.
abstract: sigma(S) is a regulator of the stationary phase response in Escherichia coli. Multi-copy suppressors were sought in a strain with decreased levels of sigma(S) and one such suppressor was found to encode HsrA, a putative efflux pump. Multi-copy expression of hsrA was shown to lead to accumulation of homocysteine, which is predicted to cause an increase in homocysteine thiolactone (HCTL) levels. A direct correlation between HCTL levels and sigma(S) accumulation was observed both in mutants and during normal cell growth, leading to the hypothesis that HCTL is a physiologically relevant positive effector of sigma(S) levels in vivo.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA. hgblair@bact.wisc.edu
authors.forename: H
authors.initials: H
authors.lastname: Goodrich-Blair
authors.forename: R
authors.initials: R
authors.lastname: Kolter
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003470:Culture Media; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D012097:Repressor Proteins; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D014805:Vitamin B 12 / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D012808:Sigma Factor; C102292:rspA protein, E coli; C069567:sigma factor KatF protein, Bacteria; D006710:Homocysteine; D008715:Methionine; C007957:homocysteine thiolactone; D014805:Vitamin B 12