The crystal structure of seabream antiquitin reveals the structural basis of its substrate specificity.
The crystal structure of seabream antiquitin in complex with the cofactor NAD(+) was solved at 2.8A resolution. The mouth of the substrate-binding pocket is guarded by two conserved residues, Glu120 and Arg300. To test the role of these two residues, we have prepared the two mutants E120A and R300A. Our model and kinetics data suggest that antiquitin's specificity towards the substrate alpha-aminoadipic semialdehyde is contributed mainly by Glu120 which interacts with the alpha-amino group of the substrate. On the other hand, Arg300 does not have any specific interaction with the alpha-carboxylate group of the substrate, but is important in maintaining the active site conformation.
Tang
Wai-Kwan
WK
Department of Biochemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
Wong
Kam-Bo
KB
Lam
Yuk-Man
YM
Cha
Sun-Shin
SS
Cheng
Christopher H K
CH
Fong
Wing-Ping
WP
D015074:2-Aminoadipic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D000444:Aldehyde Dehydrogenase / Q000737:chemistry / Q000235:genetics; D000818:Animals; D018360:Crystallography, X-Ray; D004827:Epilepsy / Q000201:enzymology; D029941:Fish Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D009154:Mutation; D009243:NAD / Q000737:chemistry*; D011487:Protein Conformation; D011736:Pyridoxine / Q000378:metabolism; D021541:Sea Bream / Q000378:metabolism*; D013379:Substrate Specificity
D029941:Fish Proteins; D009243:NAD; D015074:2-Aminoadipic Acid; C000061:allysine; C089507:ALDH7A1 protein, human; D000444:Aldehyde Dehydrogenase; D011736:Pyridoxine