Cystathionine gamma-synthase explained

cystathionine gamma-synthase
Ec Number:	2.5.1.48
Cas Number:	9030-70-0
Go Code:	0003962
Width:	270

In enzymology, a cystathionine gamma-synthase is an enzyme that catalyzes the formation of cystathionine from cysteine and an activated derivative of homoserine, e.g.:

O⁴-succinyl-L-homoserine + L-cysteine

\longrightarrow L-cystathionine + succinate

In microorganisms, the activated substrate of this enzyme is O4-succinyl-L-homoserine or O4-acetyl-L-homoserine. Cystathionine gamma-synthase from plants uses L-homoserine phosphate instead.^[1]

This enzyme belongs to the family of transferases, specifically those transferring aryl or alkyl groups other than methyl groups. The systematic name of this enzyme class is O4-succinyl-L-homoserine:L-cysteine S-(3-amino-3-carboxypropyl)transferase. Other names in common use include O-succinyl-L-homoserine succinate-lyase (adding cysteine), O-succinylhomoserine (thiol)-lyase, homoserine O-transsuccinylase, O-succinylhomoserine synthase, O-succinylhomoserine synthetase, cystathionine synthase, cystathionine synthetase, homoserine transsuccinylase, 4-O-succinyl-L-homoserine:L-cysteine, and S-(3-amino-3-carboxypropyl)transferase. This enzyme participates in 4 metabolic pathways: methionine metabolism, cysteine metabolism, selenoamino acid metabolism, and sulfur metabolism. It employs one cofactor, pyridoxal phosphate.

References

• Flavin M, Slaughter C . Enzymatic synthesis of homocysteine or methionine directly from O-succinyl-homoserine . Biochimica et Biophysica Acta . 132 . 2 . 400–5 . March 1967 . 5340123 . 10.1016/0005-2744(67)90158-1 .
• Kaplan MM, Flavin M . Cystathionine gamma-synthetase of Salmonella. Catalytic properties of a new enzyme in bacterial methionine biosynthesis . The Journal of Biological Chemistry . 241 . 19 . 4463–71 . October 1966 . 10.1016/S0021-9258(18)99743-7 . 5922970 . free .
• Wiebers JL, Garner HR . Homocysteine and cysteine synthetases of Neurospora crassa. Purification, properties, and feedback control of activity . The Journal of Biological Chemistry . 242 . 1 . 12–23 . January 1967 . 10.1016/S0021-9258(18)96312-X . 6016326 . free .
• Wiebers JL, Garner HR . Acyl derivatives of homoserine as substrates for homocysteine synthesis in Neurospora crassa, yeast, and Escherichia coli . The Journal of Biological Chemistry . 242 . 23 . 5644–9 . December 1967 . 10.1016/S0021-9258(18)99405-6 . 12325384 . free .
• Clausen T, Huber R, Prade L, Wahl MC, Messerschmidt A . Crystal structure of Escherichia coli cystathionine gamma-synthase at 1.5 A resolution . The EMBO Journal . 17 . 23 . 6827–38 . December 1998 . 9843488 . 1171030 . 10.1093/emboj/17.23.6827 .
• Ravanel S, Gakière B, Job D, Douce R . Cystathionine gamma-synthase from Arabidopsis thaliana: purification and biochemical characterization of the recombinant enzyme overexpressed in Escherichia coli . The Biochemical Journal . 331 (Pt 2) . 2 . 639–48 . April 1998 . 9531508 . 1219399 . 10.1042/bj3310639 .

Notes and References

1. Steegborn C, Laber B, Messerschmidt A, Huber R, Clausen T . Crystal structures of cystathionine gamma-synthase inhibitor complexes rationalize the increased affinity of a novel inhibitor . Journal of Molecular Biology . 311 . 4 . 789–801 . August 2001 . 11518531 . 10.1006/jmbi.2001.4880 .