Structure and function of aldehyde dehydrogenase from Thermus thermophilus: An enzyme with an evolutionarily-distinct C-terminal arm (Recombinant protein with shortened C-terminal, in complex with NADP)
Aldehyde dehydrogenases (ALDH) form a superfamily of dimeric or tetrameric enzymes that catalyze the oxidation of a broad range of aldehydes into their corresponding carboxylic acids with the concomitant reduction of the cofactor NAD(P) into NAD(P)H. Despite their varied polypeptide chain length and oligomerisation states, ALDHs possess a conserved architecture of three domains: the catalytic domain, NAD(P) + binding domain, and the oligomerization domain ...
Aldehyde dehydrogenases (ALDH) form a superfamily of dimeric or tetrameric enzymes that catalyze the oxidation of a broad range of aldehydes into their corresponding carboxylic acids with the concomitant reduction of the cofactor NAD(P) into NAD(P)H. Despite their varied polypeptide chain length and oligomerisation states, ALDHs possess a conserved architecture of three domains: the catalytic domain, NAD(P) + binding domain, and the oligomerization domain. Here, we describe the structure and function of the ALDH from Thermus thermophilus (ALDH Tt ) which exhibits non-canonical features of both dimeric and tetrameric ALDH and a previously uncharacterized C-terminal arm extension forming novel interactions with the N-terminus in the quaternary structure. This unusual tail also interacts closely with the substrate entry tunnel in each monomer providing further mechanistic detail for the recent discovery of tail-mediated activity regulation in ALDH. However, due to the novel distal extension of the tail of ALDH Tt and stabilizing termini-interactions, the current model of tail-mediated substrate access is not apparent in ALDH Tt . The discovery of such a long tail in a deeply and early branching phylum such as Deinococcus-Thermus indicates that ALDH Tt may be an ancestral or primordial metabolic model of study. This structure provides invaluable evidence of how metabolic regulation has evolved and provides a link to early enzyme regulatory adaptations.
Organizational Affiliation:
Bernal Institute, University of Limerick, Limerick, V94 T9PX, Ireland. Tewfik.Soulimane@ul.ie.
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