Rhizobium leguminosarum exopolysaccharide glucosyl ketal-pyruvate-transferase explained

Rhizobium leguminosarum exopolysaccharide glucosyl ketal-pyruvate-transferase
Ec Number:	2.5.1.98

Rhizobium leguminosarum exopolysaccharide glucosyl ketal-pyruvate-transferase (PssM) is an enzyme with systematic name phosphoenolpyruvate:(D-GlcA-beta-(1->4)-2-O-Ac-D-GlcA-beta-(1->4)-D-Glc-beta-(1->4)-(3-O-CH3-CH2CH(OH)C(O)-D-Gal-beta-(1->4)-D-Glc-beta-(1->4)-D-Glc-beta-(1->4)-D-Glc-beta-(1->6))-2(or3)-O-Ac-D-Glc-alpha-(1->6))n 4,6-O-(1-carboxyethan-1,1-diyl)transferase .^[1] This enzyme catalyses the following chemical reaction

phosphoenolpyruvate + [D-GlcA-beta-(1->4)-2-O-Ac-D-GlcA-beta-(1->4)-D-Glc-beta-(1->4)-[3-O-CH3-CH2CH(OH)C(O)-D-Gal-beta-(1->4)-D-Glc-beta-(1->4)-D-Glc-beta-(1->4)-D-Glc-beta-(1->6)]-2(or3)-O-Ac-D-Glc-alpha-(1->6)]_n

\rightleftharpoons

[D-GlcA-beta-(1->4)-2-O-Ac-D-GlcA-beta-(1->4)-D-Glc-beta-(1->4)-[3-O-CH3-CH2CH(OH)C(O)-D-Gal-beta-(1->3)-4,6-CH3(COO-)C-D-Glc-beta-(1->4)-D-Glc-beta-(1->4)-D-Glc-beta-(1->6)]-2(or3)-O-Ac-D-Glc-alpha-(1->6)]_n + phosphate

The enzyme is responsible for pyruvylation of subterminal glucose in the acidic octasaccharide repeating unit of the exopolysaccharide of Rhizobium leguminosarum.

Notes and References

Ivashina TV, Fedorova EE, Ashina NP, Kalinchuk NA, Druzhinina TN, Shashkov AS, Shibaev VN, Ksenzenko VN . Mutation in the pssM gene encoding ketal pyruvate transferase leads to disruption of Rhizobium leguminosarum bv. viciae-Pisum sativum symbiosis . Journal of Applied Microbiology . 109 . 2 . 731–42 . August 2010 . 20233262 . 10.1111/j.1365-2672.2010.04702.x .