Identification and Functional Analysis of the Gene Cluster for L-Arabinose Utilization in Corynebacterium glutamicum

• Published in: Applied and Environmental Microbiology 2009-06, Vol.75 (11), p.3419-3429
• Main Authors: Kawaguchi, Hideo, Sasaki, Miho, Vertès, Alain A, Inui, Masayuki, Yukawa, Hideaki
• Format: Article
• Language: English
• Subjects: Aerobiosis; Aldose 1-epimerase; Arabinose - metabolism; Biological and medical sciences; Carbohydrate Epimerases - genetics; Cells; Corynebacterium glutamicum; Corynebacterium glutamicum - genetics; Corynebacterium glutamicum - growth & development; Corynebacterium glutamicum - metabolism; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; E coli; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Gene Deletion; Gene expression; Gene Expression Regulation, Bacterial; Genes; Genes, Bacterial; Genetics and Molecular Biology; Glucose; Glucose - metabolism; Membrane Transport Proteins - genetics; Metabolic Networks and Pathways - genetics; Microbiology; Molecular Sequence Data; Multigene Family; Mutation; Sequence Analysis, DNA; Sequence Homology
• ISSN: 0099-2240; 1098-5336; 1098-6596
• DOI: 10.1128/AEM.02912-08

Corynebacterium glutamicum ATCC 31831 grew on L-arabinose as the sole carbon source at a specific growth rate that was twice that on D-glucose. The gene cluster responsible for L-arabinose utilization comprised a six-cistron transcriptional unit with a total length of 7.8 kb. Three L-arabinose-catabolizing genes, araA (encoding L-arabinose isomerase), araB (L-ribulokinase), and araD (L-ribulose-5-phosphate 4-epimerase), comprised the araBDA operon, upstream of which three other genes, araR (LacI-type transcriptional regulator), araE (L-arabinose transporter), and galM (putative aldose 1-epimerase), were present in the opposite direction. Inactivation of the araA, araB, or araD gene eliminated growth on L-arabinose, and each of the gene products was functionally homologous to its Escherichia coli counterpart. Moreover, compared to the wild-type strain, an araE disruptant exhibited a >80% decrease in the growth rate at a lower concentration of L-arabinose (3.6 g liter⁻¹) but not at a higher concentration of L-arabinose (40 g liter⁻¹). The expression of the araBDA operon and the araE gene was L-arabinose inducible and negatively regulated by the transcriptional regulator AraR. Disruption of araR eliminated the repression in the absence of L-arabinose. Expression of the regulon was not repressed by D-glucose, and simultaneous utilization of L-arabinose and D-glucose was observed in aerobically growing wild-type and araR deletion mutant cells. The regulatory mechanism of the L-arabinose regulon is, therefore, distinct from the carbon catabolite repression mechanism in other bacteria.