1ys4

Publication Abstract from PubMed

The structure of aspartate-beta-semialdehyde dehydrogenase (ASADH) from Methanococcus jannaschii has been determined to 2.3 angstroms resolution using multiwavelength anomalous diffraction (MAD) phasing of a selenomethionine-substituted derivative to define a new branch in the family of ASADHs. This new structure has a similar overall fold and domain organization despite less than 10% conserved sequence identity with the bacterial enzymes. However, the entire repertoire of functionally important active site amino acid residues is conserved, suggesting an identical catalytic mechanism but with lower catalytic efficiency. A new coenzyme-binding conformation and dual NAD/NADP coenzyme specificity further distinguish this archaeal branch from the bacterial ASADHs. Several structural differences are proposed to account for the dramatically enhanced thermostability of this archaeal enzyme. Finally, the intersubunit communication channel connecting the active sites in the bacterial enzyme dimer has been disrupted in the archaeal ASADHs by amino acid changes that likely prevent the alternating sites reactivity previously proposed for the bacterial ASADHs.

A new branch in the family: structure of aspartate-beta-semialdehyde dehydrogenase from Methanococcus jannaschii.,Faehnle CR, Ohren JF, Viola RE J Mol Biol. 2005 Nov 11;353(5):1055-68. Epub 2005 Sep 29. PMID:16225889^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.