Class III alcohol dehydrogenase: consistent pattern complemented with the mushroom enzyme

Abstract

Mushroom alcohol dehydrogenase (ADH) fromAgaricus bisporus (common mushroom, champignon) was puri¢ed to apparent homogeneity. One set of ADH isozymes was found, with speci¢city against formaldehyde/glutathione. It had two highly similar subunits arranged in a three-member isozyme set of dimers with indistinguishable activity. Determination of the primary structure by a combination of chemical, mass spectrometric and cDNA sequence analyses, correlated with molecular modeling towards human ADHs, showed that the active site residues are of class III ADH type, and that the subunit di¡er-ences a¡ect other residues. Class I and III forms of ADHs characterized de¢ne conserved substrate-binding residues (three and eight, respectively) useful for recognition of these enzymes in any organism.

Merging protein, gene and genomic data: the evolution of the MDR-ADH family

“…A total of 18 positions have been related with substrate binding: Thr46, Tyr49, Asp55, Glu57, His66, Glu67, Tyr92, Ile93, Leu109, Gln111, Arg114, Met140, Lys283, Val293, Ala294, Val308, Thr309 and Ala317 (Yang et al, 1997;Sanghani et al, 2002). Of these, the eight strictly conserved in ADH3 -Thr46, His66, Glu67, Arg114, Val293, Ala294, Val308 and Ala317 -have been considered a signature for direct assignment of any novel sequence (Norin et al, 2004). Finally, a large hydrophobic segment around positions 270-320 constitutes the main subunit/subunit interaction domain of the dimer (Eklund et al, 1990).…”

“…Besides the Thr/Ser48, class I enzymes share three positions, His67, Glu68 and Phe140, thus far strictly conserved. This triad has been proposed as a signature for class assignment in further gene analyses (Norin et al, 2004), although preservation of these positions does not necessarily imply ethanol oxidizing activity (Reimers et al, 2004), as discussed below. When the distribution of the constant and variable segments of class I and III was compared, further differences were found (Danielsson et al, 1994a).…”

Oikopleura dioica Alcohol Dehydrogenase Class 3 Provides New Insights into the Evolution of Retinoic Acid Synthesis in Chordates

“…Analysis of conservation of key functional residues indicates that the Oikopleura Adh3 enzyme shows the typical features of a class-3 form. Oikopleura Adh3 strictly conserves the eight residues that constitute the signature of all Adh3 enzymes (Norin et al, 2004), as well as the twenty-two residues that had been described to be crucial for Adh3 biochemical activity (Table 1). Remarkably, Adh3 enzymes have a single conformation ("semi-open") for the catalytic domain, while Adh enzymes with high affinity for retinol and small alcohols (i.e., Adh1) have two alternative conformations (either "open" or "closed") (Sanghani et al, 2003), reviewed by GonzalezDuarte and Albalat (2005).…”

“…The inferred sequence of the Oikopleura Adh enzyme included the strictly conserved eight residues that have been defined as the signature of the Adh3 enzymes: T46, H66, E67, R114, V293, A294, V308, and A317 (labeled in grey in Table 1; Norin et al, 2004). In addition, Oikopleura Adh3 showed high amino acid conservation (Table 1) in the 18 positions associated with the substrate-binding domain, the four positions relevant for the catalytic activity, the three positions relevant for coenzyme binding, and the four positions relevant for the coordination of the active zinc in Adh3 enzymes (Yang et al, 1997;Sanghani et al, 2002), reviewed by Gonzalez-Duarte and Albalat (2005).…”