Species: Galium mollugo
Protein extracts obtained from cell cultures of Galium mollugo mediate the conversion of 2-succinylbenzoate (OSB) to 4-(2'-carboxyphenyl)-4-oxobutyryl-CoA in the presence of CoA and ATP [Heide82]. Three CoA esters are generated under in vitro conditions, the mono-CoA ester 4-(2'-carboxyphenyl)-4-oxobutyryl CoA ("aliphatic" CoA, described in this pathway), the mono-CoA ester 2-(3'-carboxypropionyl)benzoyl CoA ("aromatic" CoA), and a di-CoA ester, 4-(2'-carboxyphenyl)-4-oxobutyryl-di-CoA. However, only the "aliphatic" CoA ester was further convertable to 1,4-dihydroxy-2-naphtoic acid (DHNA) by a microbial naphtoate synthase enzyme, indicating that this isomer is the true in vivo product [Kolkmann87].
Unlike the bacterial O-succinylbenzoate-CoA ligase which is AMP and diphosphate forming, the plant enzyme is activated by ATP with ADP and phosphate forming. ADP and phosphate have product inhibition of the enzyme activity. A 50% inhibition was observed with 5.3 mM ADP, and 0.35 mM phosphate, respectively. The enzyme is highly substrate specific. Analogues of O-succinoylbenzoate such as O-malonylbenzoate, benzoylpropionate, benzoate, 2-acetylbenzoate and p-coumarate were not accepted. The enzyme activity requires Mg2+. Ca2+, Cu2+ and Zn2+ could not replace Mg2+, whereas, Ni2+ (85% compared to Mg2+), Mn2+ (75%) and Co2+ (66%) gave partial activity [Sieweke92].
Revised 08-Feb-2008 by Zhang P
Enzymatic reaction of: O-succinylbenzoate-CoA ligase
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is physiologically favored in the direction shown.
T(opt): 28 °C [Sieweke92]
pH(opt): 6.8 [Sieweke92]
Heide82: Heide L, Kolkmann R, Arendt S, Leistner E (1982). "Enzymic synthesis of o-succinylbenzoyl-CoA in cell-free extracts of anthraquinone producing Galium mollugo L. cell suspension cultures." Plant Cell Reports, 1, 180-182.
Sieweke92: Sieweke, Hans-Jurgen, Leistner, Eckhard (1992). "O-succinylbenzoate: coenzyme A ligase from anthraquinone producing cell suspension cultures of Galium mollugo." Phytochemistry 31(7): 2329-2335.
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