Yeast Alcohol Dehydrogenase Structure and Catalysis

Abstract

Yeast (Saccharomyces cerevisiae) alcohol dehydrogenase I (ADH1) is the constitutive enzyme that reduces acetaldehyde to ethanol during the fermentation of glucose. ADH1 is a homotetramer of subunits with 347 amino acid residues. A structure for ADH1 was determined by X-ray crystallography at 2.4 Å resolution. The asymmetric unit contains four different subunits, arranged as similar dimers named AB and CD. The unit cell contains two different tetramers made up of “back-to-back” dimers, AB:AB and CD:CD. The A and C subunits in each dimer are structurally similar, with a closed conformation, bound coenzyme, and the oxygen of 2,2,2-trifluoroethanol ligated to the catalytic zinc in the classical tetrahedral coordination with Cys-43, Cys-153, and His-66. In contrast, the B and D subunits have an open conformation with no bound coenzyme, and the catalytic zinc has an alternative, inverted coordination with Cys-43, Cys-153, His-66, and the carboxylate of Glu-67. The asymmetry in the dimeric subunits of the tetramer provides two structures that appear to be relevant for the catalytic mechanism. The alternative coordination of the zinc may represent an intermediate in the mechanism of displacement of the zinc-bound water with alcohol or aldehyde substrates. Substitution of Glu-67 with Gln-67 decreases the catalytic efficiency by 100-fold. Previous studies of structural modeling, evolutionary relationships, substrate specificity, chemical modification, and site-directed mutagenesis are interpreted more fully with the three-dimensional structure.

Overproduction of squalene synergistically downregulates ethanol production in Saccharomyces cerevisiae

“…Pyruvate decarboxylase (PDC5) is a key enzyme of alcoholic fermentation, which converts the pyruvate into acetaldehyde (Goffeau A, 1996). Alcohol dehydrogenase 1 (ADH1) and alcohol dehydrogenase V (ADH5) are fermentative isozymes and they catalyze the reduction of acetaldehyde into ethanol (Raj S, 2014). Alcohol dehydrogenase IV (ADH4) also catalyzes the reduction of acetaldehyde into ethanol (Drewke C, 1988).…”

Effects of Macromolecular Crowding on Alcohol Dehydrogenase Activity Are Substrate-Dependent

“…The reaction consists of a stereospecific hydride transfer from the alcohol to the cofactor and a series of conformational changes that are likely to be influenced by crowding. 34 For the natural substrate ethanol (EtOH), the slow step of the mechanism is the release of the NADH product. 35 For larger alcohols, such as isopropanol and benzyl alcohol, the hydride transfer becomes rate-limiting.…”

Scaffold electrodes based on thioctic acid-capped gold nanoparticles coordinated Alcohol Dehydrogenase and Azure A films for high performance biosensor

“…In this case the cofactor acts as a second substrate, for this reason these enzymes are called dehydrogenases dependent on NAD + . Yeast alcohol dehydrogenase (ADH) is a tetramer of four identical subunits [12] with 347 amino acid residues each and a calculated mass of 147.396 Da (36.849 Da/subunit), each subunit contains two zinc (II) ions that are tetracoordinated [13]. The zinc ion located in the catalytic lobe is coordinated with two cysteines, one glutamic and one histidine.…”

“…It is involved in the catalytic oxidation of ethanol. The other zinc ion is coordinated with four cysteines [12] and is located in a structural lobe. In the active center this enzyme has two binding domains: the first one binds the substrate (ethanol) and the second one is reserved for the oxidized form of the cofactor [14].…”