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Hydroxy(phenyl)pyruvate Reductase, D-isomer-specific 2-hydroxyacid-related dehydrogenase Hydroxy(phenyl)pyruvate reductase (HPPR) catalyzes the NADP-dependent reduction of hydroxyphenylpyruvates, hydroxypyruvate, or pyruvate to its respective lactate. HPPR acts as a dimer and is related to D-isomer-specific 2-hydroxyacid dehydrogenases, a superfamily that includes groups such as formate dehydrogenase, glycerate dehydrogenase, L-alanine dehydrogenase, and S-Adenosylhomocysteine Hydrolase. Despite often low sequence identity, these proteins typically have a characteristic arrangement of 2 similar subdomains of the alpha/beta Rossmann fold NAD+ binding form. The NAD+ binding domain is inserted within the linear sequence of the mostly N-terminal catalytic domain, which has a similar domain structure to the internal NAD binding domain. Structurally, these domains are connected by extended alpha helices and create a cleft in which NAD is bound, primarily to the C-terminal portion of the 2nd (internal) domain. Some related proteins have similar structural subdomain but with a tandem arrangement of the catalytic and NAD-binding subdomains in the linear sequence. While many members of this family are dimeric, alanine DH is hexameric and phosphoglycerate DH is tetrameric. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",