Abstract
Homoserine dehydrogenase (HSD; 305 amino acid residues) catalyzes an NAD(P)-dependent reversible reaction between l-homoserine and aspartate 4-semialdehyde and is involved in the aspartate pathway. HSD from the hyperthermophilic archaeon Sulfolobus tokodaii was markedly activated (2.5-fold) by the addition of 0.8mM dithiothreitol. The crystal structure of the homodimer indicated that the activation was caused by cleavage of the disulfide bond formed between two cysteine residues (C303) in the C-terminal regions of the two subunits.
Highlights
Homoserine dehydrogenase (HSD) (EC 1.1.1.3) catalyzes the reversible NAD(P)-dependent oxidation of L-homoserine to L-aspartate 4-semialdehyde and NAD (P)H
Because its product L-homoserine is a precursor of L-threonine, L-cysteine, and L-methionine and its substrate L-aspartate 4-semialdehyde is a precursor of L-lysine, HSD plays a key regulatory role in the pathway
HSD from Corynebacterium glutamicum is inhibited by both threonine and methionine [4], and the enzyme from Thermus flavus AT-62 is inhibited by cysteine [5]
Summary
HSD (EC 1.1.1.3) catalyzes the reversible NAD(P)-dependent oxidation of L-homoserine to L-aspartate 4-semialdehyde and NAD (P)H. We succeeded in overexpression of the gene product in E. coli and found that the purified enzyme is uniquely activated by a reducing agent DTT. The oxidized form was prepared by the pre-treatment of StHSD with 0.1 mM potassium ferricyanide for 2 h.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
