Differential expression of genes within the gap operon of Clostridium acetobutylicum

Transcriptional analyses by Northern (RNA) blot, primer extension, and reve rse transcriptase (RT)-PCR experiments revealed that the gap, pgk, and tpi genes of Clostridium acetobutylicum are organized within a common operon. T ranscriptional start points were identified upstream of gap, tpi, and adjac ent to pgm(i), which is not part of the gap operon. Four transcripts of dif ferent abundance corresponding to gap, gap-pgk, gap-pgk-tpi, and tpi could be identified. Sequence comparisons indicate the existence of RNase III and RNase E gene homologues in the C. acetobutylicum genome. Determination of transcript half-lives and the absence of rho-independent transcription term inators in the intergenic regions indicate that the most abundant gap trans cript is a stable degradation product of the full-length message. Understan ding the regulation of glycolytic gene expression will result in developmen t of fermentation conditions allowing enhanced glycolytic flux to improve s olvent formation in C. acetobutylicum. (C) 2000 Academic Press.