Molecular analysis and nucleotide sequence of the adh1 gene encoding an NADPH-dependent butanol dehydrogenase in the Gram-positive anaerobe Clostridium acetobutylicum

The nucleotide sequence of a 2081-bp fragment of Clostridium acetobutylicum DNA containing the adh1 gene was determined. The butanol dehydrogenase gene is referred to as the adh1 gene since it was shown to have activity using butanol and ethanol as substrates. The adh1 gene consisted of 1164 bp and encoded an alcohol dehydrogenase (ADH) enzyme of 388 aa residues with an Mr of 43,274. The adh1 gene was separated from an upstream open reading frame by an intergenic region of 354 bp. No promoter consensus sequences were identified in the intergenic upstream region and the adh1 gene did not appear to be expressed off its own promoter in Escherichia coli. Three separate types of ADH have been recognized. The ADH1 from C. acetobutylicum exhibited 39% homology with the Fe-containing ADH2 from Zymomonas mobilis and 37% homology with the ADH4 from Saccharomyces cerevisiae, but showed little or no homology with the other characterised types of ADH.