title: Cytosolic Ca2+ regulates protein expression in E. coli through release from inclusion bodies.
abstract: The results here are the first clear demonstration of a physiological role for cytosolic Ca(2+) in Escherichia coli by releasing a Ca(2+) binding protein, apoaequorin, from inclusion bodies. In growth medium LB the cytosolic free Ca(2+) was 0.1-0.3 microM. Addition of EGTA reduced this to <0.1 microM, whereas addition of Ca(2+) (10mM) resulted in a cytosolic free Ca(2+) of 1-2 microM for at least 2h. Ca(2+) caused a 1.5- to 2-fold increase in the level of apoaequorin induced by IPTG. Whereas EGTA induced a 50% decrease. The effect of a Ca(2+) was explained by release of protein from the inclusion bodies, together with a stabilisation of apoaequorin against degradation. Ca(2+) also reduced the generation time by 4-5 min. These results have important implications for unravelling the physiological role of cytosolic Ca(2+) in bacteria, particularly where several species are competing for the same nutrients, such as in the gut.
authors.affiliation: Department of Medical Biochemistry and Immunology, Tenovus building, Cardiff University, Heath Park, Cardiff CF14 XN, UK.
authors.forename: Riffat
authors.initials: R
authors.lastname: Naseem
authors.forename: Sally Rosser
authors.initials: SR
authors.lastname: Davies
authors.forename: Helen
authors.initials: H
authors.lastname: Jones
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Wann
authors.forename: I Barry
authors.initials: IB
authors.lastname: Holland
authors.forename: Anthony K
authors.initials: AK
authors.lastname: Campbell
mesh_terms: D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism* / Q000648:ultrastructure; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D002479:Inclusion Bodies / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000502:physiology*
chemical_list: D029968:Escherichia coli Proteins; D002118:Calcium