AdeR, a PucR-type transcription factor, activates expression of L-alanine dehydrogenase and is required for sporulation of Bacillus subtilis.
The Bacillus subtilis ald gene encodes L-alanine dehydrogenase, which catalyzes the NAD(+)-dependent deamination of L-alanine to pyruvate for the generation of energy and is required for normal sporulation. The transcription of ald is induced by alanine, but the mechanism underlying alanine induction remains unknown. Here we report that a gene (formerly yukF and now designated adeR) located upstream of ald is essential for the basal and alanine-inducible expression of ald. The disruption of the adeR gene caused a sporulation defect, whereas the complementation of an adeR mutation with an intact adeR gene restored the sporulation ability. adeR expression was not subject to autoregulation and alanine induction. Deletion and mutation analyses revealed that an inverted repeat, centered at position -74.5 relative to the transcriptional initiation site of ald, was required for ald expression and also likely served as a ρ-independent transcription terminator. Electrophoretic mobility shift assays showed that purified His-tagged AdeR was a specific DNA-binding protein and that this inverted repeat was required for AdeR binding. AdeR shows no significant amino acid sequence similarity to the known transcriptional activators of ald genes from other bacteria. AdeR appears to be a member of the PucR family of transcriptional regulators. Its orthologs of unknown function are present in some other Bacillus species. Collectively, these findings support the notion that AdeR is a transcriptional activator which mediates ald expression in response to alanine availability and is important for normal sporulation in B. subtilis.
Institute of Biochemistry and Molecular Biology, School of Life Science, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Ta-Hui
TH
Lin
Guei-Tsung
GT
Wei
Chien-Chen
CC
Su
Gwo-Chyuan
GC
Shaw
D050788:Alanine Dehydrogenase / Q000096:biosynthesis*; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development*; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013171:Spores, Bacterial / Q000254:growth & development*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004269:DNA, Bacterial; D014157:Transcription Factors; D050788:Alanine Dehydrogenase