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PMID:10406936

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Citation

Shafqat, J, Höög, JO, Hjelmqvist, L, Oppermann, UC, Ibáñez, C and Jörnvall, H (1999) An ethanol-inducible MDR ethanol dehydrogenase/acetaldehyde reductase in Escherichia coli: structural and enzymatic relationships to the eukaryotic protein forms. Eur. J. Biochem. 263:305-11

Abstract

An ethanol-active medium-chain dehydrogenase/reductase (MDR) alcohol dehydrogenase was isolated and characterized from Escherichia coli. It is distinct from the fermentative alcohol dehydrogenase and the class III MDR alcohol dehydrogenase, both already known in E. coli. Instead, it is reminiscent of the MDR liver enzyme forms found in vertebrates and has a K(m) for ethanol of 0.7 mM, similar to that of the class I enzyme in humans, however, it has a very high k(cat), 4050 min(-1). It is also inhibited by pyrazole (K(i) = 0.2 microM) and 4-methylpyrazole (K(i)= 44 microM), but in a ratio that is the inverse of the inhibition of the human enzyme. The enzyme is even more efficient in the reverse direction of acetaldehyde reduction (K(m) = 30 microM and k(cat) = 9800 min(-1)), suggesting a physiological function like that seen for the fermentative non-MDR alcohol dehydrogenase. Growth parameters in complex media with and without ethanol show no difference. The structure corresponds to one of 12 new alcohol dehydrogenase homologs present as ORFs in the E. coli genome. Together with the previously known E. coli MDR forms (class III alcohol dehydrogenase, threonine dehydrogenase, zeta-crystallin, galactitol-1-phosphate dehydrogenase, sensor protein rspB) there is now known to be a minimum of 17 MDR enzymes coded for by the E. coli genome. The presence of this bacterial MDR ethanol dehydrogenase, with a structure compatible with an origin separate from that of yeast, plant and animal ethanol-active MDR forms, supports the view of repeated duplicatory origins of alcohol dehydrogenases and of functional convergence to ethanol/acetaldehyde activity. Furthermore, this enzyme is ethanol inducible in at least one E. coli strain, K12 TG1, with apparently maximal induction at an enthanol concentration of approximately 17 mM. Although present in several strains under different conditions, inducibility may constitute an explanation for the fairly late characterization of this E. coli gene product.

Links

PubMed

Keywords

Alcohol Dehydrogenase/chemistry; Alcohol Dehydrogenase/classification; Amino Acid Sequence; Amino Acids/chemistry; Escherichia coli/enzymology; Ethanol/metabolism; Humans; Kinetics; Molecular Sequence Data; Phylogeny; Sequence Homology, Amino Acid; Structure-Activity Relationship

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ECOLI:ADHP

enables

GO:0004022: alcohol dehydrogenase (NAD+) activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:ADHP

NOT|enables

GO:0047639: alcohol oxidase activity

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ECOLI:ADHP

involved_in

GO:0046187: acetaldehyde catabolic process

ECO:0000314: direct assay evidence used in manual assertion

P

Seeded From UniProt

complete

ECOLI:ADHP

involved_in

GO:0045471: response to ethanol

ECO:0000270: expression pattern evidence used in manual assertion

P

Seeded From UniProt

complete


See also

References

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