Archaeal Aldehyde Dehydrogenase ST0064 from Sulfolobus tokodaii, a Paralog of Non-Phosphorylating Glyceraldehyde-3-phosphate Dehydrogenase, Is a Succinate Semialdehyde Dehydrogenase

摘要

Aldehyde dehydrogenase ST0064, the closest paralog of previously characterized allosteric non-phosphorylat-ing glyceraldehyde-3-phosphate (GAP) dehydrogenase (GAPN, ST2477) from a thermoacidophilic archaeon, Sulfolobus tokodaii, was expressed heterologously and characterized in detail. ST0064 showed remarkable activity toward succinate semialdehyde (SSA) (K_m of 0.0029 dim and k_(cat) of 30.0 s~(-1)) with no allosteric regulation. Activity toward GAP was lower (K_m of 4.6 mM and k_(cat) of 4.77 s~(-1)), and previously predicted succinyl-CoA reductase activity was not detected, suggesting that the enzyme functions practically as succinate semialdehyde dehydrogenase (SSADH). Phyloge-netic analysis indicated that archaeal SSADHs and GAPNs are closely related within the aldehyde dehydrogenase superfamily, suggesting that they are of the same origin.