Cold induction of the Bacillus subtilis bkd operon is mediated by increased mRNA stability.
Recently it has been demonstrated that the ptb - bcd - buk - lpdV - bkdAA - bkdAB - bkdB operon ( bkdoperon) of Bacillus subtilis, which encodes the enzymes that catalyze the degradation of branched-chain amino acids, is inducible by a temperature downshift from 37 to 18 degrees C. Deamination and oxidative decarboxylation of isoleucine generates 2-methyl-butyryl-CoA, which serves as the precursor of anteiso-branched fatty acid species. Most probably, the induction of this operon upon cold shock ensures an increase in the content of anteiso-branched fatty acids in the membrane lipids at low temperature, thus permitting maintenance of membrane fluidity at lower temperatures. In the present study, we have analyzed the mechanism of cold induction of the bkd operon and of four further cold-inducible transcriptional units in B. subtilis. We demonstrate that cold induction of these genes is mediated by an increase in the stability of the corresponding mRNAs. None of the promoters that control the five transcriptional units analyzed is actually cold-inducible. Furthermore, the results of this study indicate that the 5' leader regions are not involved in the cold-induced stabilization of the mRNAs. The structural elements that enhance mRNA stability must therefore be restricted to the 3'-ends and/or the coding regions.
Nickel
M
M
Institut für Mikrobiologie und Molekularbiologie, Ernst-Moritz-Arndt-Universität Greifswald, 17487, Greifswald, Germany.
Homuth
G
G
Böhnisch
C
C
Mäder
U
U
Schweder
T
T
D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D017930:Genes, Reporter; D051756:Leucine-Responsive Regulatory Protein; D012333:RNA, Messenger / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013696:Temperature; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C400921:mntA protein, Lactobacillus plantarum; D051756:Leucine-Responsive Regulatory Protein; D001616:beta-Galactosidase