Analysis of the leuB gene from Corynebacterium glutamicum.
The leuB gene of Corynebacterium glutamicum was found to be present on a 2.2-kb BamHI-SacI chromosomal fragment which complemented the leuB mutation of Escherichia coli. The activity of 3-isopropylmalate dehydrogenase (EC 1.1.1.85), encoded by the leuB gene, was significantly increased in C. glutamicum cells harbouring a plasmid containing the 2.2-kb fragment. The nucleotide sequence of the C. glutamicum leuB coding region (an open reading frame, ORF, of 1020 bp encoding a polypeptide of 340 amino acids with M(r) of 36 144) was determined. The deduced amino acid sequence of the product of this ORF is highly homologous to those of 3-isopropylmalate dehydrogenases from three species of mycobacteria. The transcriptional start site of the leuB gene was localized 35 bp upstream of its translational start; a functional terminator was detected in the 3' flanking region. Northern hybridization analysis showed that the C. glutamicum leuB gene is transcribed as a single monocistronic RNA (approximately 1.2 kb in size). Activity of the leuB promoter was significantly reduced when leucine was present in the growth medium. This suggests the negative regulation of the leuB expression on the transcriptional level in C. glutamicum cells.
Institute of Microbiology, Academy of Sciences of the Czech Republic, Praha, Czech Republic.
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Pátek
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Hochmannová
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Jelínková
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Nesvera
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Eggeling
D050539:3-Isopropylmalate Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D003352:Corynebacterium / Q000201:enzymology* / Q000235:genetics; D017931:DNA Primers / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry*; D004587:Electrophoresis, Agar Gel; D004926:Escherichia coli / Q000737:chemistry; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D007930:Leucine / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010957:Plasmids / Q000737:chemistry; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000737:chemistry*; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D000429:Alcohol Oxidoreductases; D050539:3-Isopropylmalate Dehydrogenase; D007930:Leucine