Search

Abstract: A mutant of Corynebacterium glutamicum ATCC 13032 with a deletion of the atpBEFHAGDC genes encoding F1FO-ATP synthase was characterized. Whereas no growth was observed with acetate as sole carbon source, the ΔF1FO mutant reached 47% of the growth rate and 65% of the biomass of the wild type during shake-flask cultivation in glucose minimal medium. Initially, the mutant strain showed a strongly increased glucose uptake rate accompanied by a high oxygen consumption rate and pyruvate secretion into the medium. When oxygen became limiting, the glucose consumption rate was reduced below that of the wild type and pyruvate was consumed again. The ΔF1FO mutant had increased levels of b- and d-type cytochromes and a significantly increased proton motive force. Transcription of genes involved in central carbon metabolism was essentially unchanged, whereas genes for cytochrome bd oxidase, pyruvate:quinone oxidoreductase, oxidative stress response, and others showed increased mRNA levels. On the other hand, genes for amino acid biosynthesis and ribosomal proteins as well as many genes involved in transport displayed decreased mRNA levels. Several of the transcriptional changes were reflected at the protein level, but there were also discrepancies between the mRNA and protein levels suggesting some kind of posttranscriptional regulation. The results prove for the first time that F1FO-ATP synthase and oxidative phosphorylation are in general not essential for growth of C. glutamicum. [Copyright &y& Elsevier]