title: Transcriptional analysis of catabolite repression in Clostridium acetobutylicum growing on mixtures of D-glucose and D-xylose.
abstract: Clostridium acetobutylicum is a strict anaerobic organism that is used for biotechnological butanol fermentation. It ferments various hexoses and pentoses to solvents but prefers glucose presumably using a catabolite repression mechanism. Accordingly during growth on a mixture of D-glucose and D-xylose a typical diauxic growth pattern was observed. We used DNA microarrays and real-time RT-PCR to study gene expression during growth on D-glucose, D-xylose mixtures on a defined minimal medium together with monitoring substrate consumption and product formation. We identified two putative operons involved in D-xylose degradation. The first operon (CAC1344-CAC1349) includes a transporter, a xylulose-kinase, a transaldolase, a transketolase, an aldose-1-epimerase and a putative xylose isomerase that has been annotated as an arabinose isomerase. This operon is induced by D-xylose but was catabolite repressed by D-glucose. A second operon (CAC2610-CAC2612) consists of a xylulose-kinase, a hypothetical protein and a gene that has been annotated as a L-fucose isomerase that might in fact code for a xylose isomerase. This operon was induced by D-xylose but was not subject to catabolite repression. In accordance with these results we identified a CRE site in the catabolite repressed operon but not in the operon that was not subject to catabolite repression.
authors.affiliation: Abteilung für Genomische und Angewandte Mikrobiologie, Institut für Mikrobiologie und Genetik, Georg-August Universität Göttingen, Grisebachstr. 8, D-37077 Göttingen, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Grimmler
authors.forename: Claudia
authors.initials: C
authors.lastname: Held
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Liebl
authors.forename: Armin
authors.initials: A
authors.lastname: Ehrenreich
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000440:Butanols / Q000378:metabolism; D046969:Clostridium acetobutylicum / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005285:Fermentation; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014994:Xylose / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D000440:Butanols; D012097:Repressor Proteins; D014994:Xylose; D005947:Glucose