Extracellular lipases from Bacillus subtilis: regulation of gene expression and enzyme activity by amino acid supply and external pH.
Bacillus subtilis secretes two lipases LipA and LipB into the culture medium. Both enzyme genes were differentially expressed depending on the growth conditions as determined by activity assays and Western blotting in B. subtilis mutant strains lipA, lipB, and the corresponding lipA/lipB double mutant. In minimal medium, LipA was produced at wild-type level in a lipB mutant, however, no LipB protein was detected in a lipA mutant. Interestingly, LipA was produced and secreted at wild-type level in rich medium, but the enzyme remained enzymatically inactive, presumably being caused by a shift of the growth medium to acid pH. Furthermore, expression of the lipase genes was studied using transcriptional fusions with the lacZ reporter gene. The expression of lipA was repressed by high amino acid concentrations, whereas the lipB gene expression remained unaffected.
Eggert
Thorsten
T
Institut für Molekulare Enzymtechnologie, Heinrich-Heine Universität Duesseldorf, Forschungszentrum Juelich, D-52426 Juelich, Germany.
Brockmeier
Ulf
U
Dröge
Melloney J
MJ
Quax
Wim J
WJ
Jaeger
Karl-Erich
KE
D000596:Amino Acids / Q000378:metabolism*; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics*; D015153:Blotting, Western; D002210:Caprylates / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000235:genetics* / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
D000596:Amino Acids; D002210:Caprylates; C034106:4-nitrophenyloctanoate; D008049:Lipase; D001616:beta-Galactosidase