Substrate specificity of nine NAD+-dependent alcohol dehydrogenases in Aspergillus nidulans

Abstract

In Aspergillus nidulans three alcohol dehydrogenases (ADHs) have been described. ADHI is induced by ethanol and is the physiological enzyme of ethanol utilization, ADHll has not been attributed a function but is repressed by ethanol. The ALCR regulatory protein acts positively to induce ADHI, and negatively in its control of ADHII. ADHlll is specifically induced by anaerobic stress. We have characterized the substrate specificity of these three enzymes by looking at their staining profile on polyacrylamide gels with a range of alcohols. In addition to these enzymes we have observed six other NAD+-dependent ADHs, two of which, propan-2-01 dehydrogenase and pentan-2-01 dehydrogenase, share similar control with ADHII. The inducibility of these enzymes with some alcohols has also been investigated. The profile of ADHs with NADP' as an electron acceptor is also reported.

ADHII in Aspergillus nidulans Is Induced by Carbon Starvation Stress

“…Propan-2-ol dehydrogenase and pentan-2-ol dehydrogenase are derepressed in alcA Ϫ and alcR Ϫ mutants when transferred to ethanol medium (Sealy- Lewis and Fairhurst, 1995). In the facA and facB mutants transferred to acetate, both these activities are derepressed in addition to ADHII, whereas in the aldA mutant there is some derepression on transfer to acetate, but this is not as marked as with the other mutants (data not shown).…”

“…We also examined the behavior of an alcR125 creA d 1 double-mutant strain that showed high levels of ADHII on ethanol medium, but again on ethanol ϩ glucose or on fructose ϩ glucose, ADHII was still absent. We have described previously two other enzymes, propan-2-ol dehydrogenase and pentan-2-ol dehydrogenase, which, like ADHII, are absent on ethanol ϩ glucose medium (Sealy- Lewis and Fairhurst, 1995), and in the creA d 30 strain these enzymes are not expressed (data not shown).…”

“…In Aspergillus nidulans there are at least nine NAD ϩ -dependent alcohol dehydrogenases (ADHs), of which only three (ADH1, ADHII, and ADHIII) are capable of utilizing ethanol as a substrate (Sealy-Lewis and Fairhurst, 1995). ADHI is inducible by ethanol and is the physiological enzyme of ethanol utilization.…”

Horizontal gene acquisitions by eukaryotes as drivers of adaptive evolution

“…Figure displays two potential HGTs adding pseudoparalogs (in the sense of a pan‐genomic gene duplication ) to a family of alcohol dehydrogenases in G. sulphuraria . It seems likely that the different alcohol dehydrogenases in G. sulphuraria have different substrate specificities, as is known to occur in other species . In eukaryotes, gene families with several paralogs usually result from gene duplications followed by neo‐ or sub‐functionalization .…”

Developmental and environmental influences in the production of a single NAD-dependent fermentative alcohol dehydrogenase by the zygomycete Mucor rouxii

“…ADHIII (structural gene, alcC) is produced under conditions of anaerobic stress (Kelly et al 1990). A range of other ADHs with distinct electrophoretic mobility and substrate specificity different from that of the previously described enzymes has been further demonstrated in A. nidulans (Sealy-Lewis and Fairhurst 1995).…”