The quaternary structure of Thermus thermophilus aldehyde dehydrogenase is stabilized by an evolutionary distinct C-terminal arm extension

Abstract

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 (ALDHTt) 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 ALDHTt and stabilizing termini-interactions, the current model of tail-mediated substrate access is not apparent in ALDHTt. The discovery of such a long tail in a deeply and early branching phylum such as Deinococcus-Thermus indicates that ALDHTt 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.

Insights into Aldehyde Dehydrogenase Enzymes: A Structural Perspective

“…However, emerging research suggests the contrary. The novel ALDH from T. thermophilus HB27 (TtALDH 530 ) Hayes et al (2018) showed an interesting feature with an unusual extended C-terminal tail compared to available structures (Figure 7). In contrast to other ALDHs, this extended tail contributes to the tetrameric assembly and the stability of the protein as it completely wraps the opposing monomer.…”

“…To date 10 out of the 19 human ALDHs have a resolved structure. Initially this led to misconceptions and a rather inaccurate description of typical features related to the enzyme family (Rodríguez-Zavala et al, 2006;Hayes et al, 2018). Emerging research allows for an accurate understanding of diversity within the ALDH family, across prokaryotes and eukaryotes, while bridging the gap to form a global perception of the superfamily.…”

Study of ALDH from Thermus thermophilus—Expression, Purification and Characterisation of the Non-Substrate Specific, Thermophilic Enzyme Displaying Both Dehydrogenase and Esterase Activity

“…While ALDHs have been well-characterised in humans, emerging research places a primary focus on their prokaryotic counterpart’s structure and function, which has been less explored until recently [ 29 , 30 , 31 ]. The scope of prokaryotic ALDH function spans much wider than eukaryotes [ 5 , 19 , 31 , 32 ].…”

Combined epigenetic and metabolic inhibition blocks platinum-induced ovarian cancer stem cell enrichment

“…The metabolite nicotinamide adenine dinucleotide (NAD + ) plays a key role in major metabolic pathways including glycolysis, tricarboxylic acid (TCA) cycle, and oxidative phosphorylation (19). Furthermore, NAD + is a co-factor for ALDH enzymes and essential for the ALDH-mediated conversion of aldehydes to carboxylic acids (20,21). Ovarian tumors with reduced expression of BRCA1 through BRCA1 promoter DNA hypermethylation or mutation have increased levels of NAD + and expression of nicotinamide phosphoribosyltranferase (NAMPT), the rate limiting regulator of NAD + synthesis from the salvage pathway (22).…”