Bacillus subtilis aconitase is required for efficient late-sporulation gene expression.
Bacillus subtilis aconitase, encoded by the citB gene, is homologous to the bifunctional eukaryotic protein IRP-1 (iron regulatory protein 1). Like IRP-1, B. subtilis aconitase is both an enzyme and an RNA binding protein. In an attempt to separate the two activities of aconitase, the C-terminal region of the B. subtilis citB gene product was mutagenized. The resulting strain had high catalytic activity but was defective in sporulation. The defect was at a late stage of sporulation, specifically affecting expression of sigmaK-dependent genes, many of which are important for spore coat assembly and require transcriptional activation by GerE. Accumulation of gerE mRNA and GerE protein was delayed in the aconitase mutant strain. Pure B. subtilis aconitase bound to the 3' untranslated region of gerE mRNA in in vitro gel mobility shift assays, strongly suggesting that aconitase RNA binding activity may stabilize gerE mRNA in order to allow efficient GerE synthesis and proper timing of spore coat assembly.
Serio
Alisa W
AW
Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
Pechter
Kieran B
KB
Sonenshein
Abraham L
AL
D000154:Aconitate Hydratase / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D017354:Point Mutation; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment; D013171:Spores, Bacterial / Q000254:growth & development; D014157:Transcription Factors / Q000378:metabolism
D001426:Bacterial Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C084190:sigma K; C030069:spore-specific proteins, Bacillus; D000154:Aconitate Hydratase