Cytosolic Ca2+ regulates protein expression in E. coli through release from inclusion bodies.
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.
Naseem
Riffat
R
Department of Medical Biochemistry and Immunology, Tenovus building, Cardiff University, Heath Park, Cardiff CF14 XN, UK.
Davies
Sally Rosser
SR
Jones
Helen
H
Wann
Kenneth T
KT
Holland
I Barry
IB
Campbell
Anthony K
AK
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*
D029968:Escherichia coli Proteins; D002118:Calcium