Biosynthesis of cadaverine-containing peptidoglycan in Selenomonas ruminantium.

Cadaverine links covalently to the D-glutamic acid residue of the peptidoglycan in Selenomonas ruminantium, a strictly anaerobic, Gram-negative bacterium (Kamio, Y., Itoh, Y., and Terawaki, Y (1981) J. Bacteriol. 146, 49-53). This report describes the enzymatic properties of the particulate enzyme preparation in S. ruminantium which catalyzes the addition of cadaverine to the alpha-carboxyl group of D-glutamic acid residue of the peptidoglycan. Incorporation of cadaverine into the peptidoglycan required UDP-MurNAc-L-Ala-D-Glu-meso-2,5-diaminopimelic acid (DAP)-D-Ala-D-Ala (UDP-MurNAc-pentapeptide(DAP)), UDP-GlcNAc, and ATP. In addition, MgCl2 and cysteine stimulated the reaction. UDP-MurNAc-pentapeptide(DAP) could not be substituted for UDP-MurNAc-L-Ala-D-Glu-L-Lys-D-Ala-D-Ala as a precursor of cadaverine-containing peptidoglycan. GlcNAc-MurNAc-pentapeptide(DAP)-lipid (disaccharide-pentapeptide(DAP)-lipid) prepared enzymatically acted as an immediate acceptor of cadaverine in an ATP-dependent reaction in which the alpha-carboxyl group of D-glutamic acid is covalently linked to cadaverine. The [14C]cadaverine-containing disaccharide-pentapeptide(DAP)-lipid was isolated, and used for the synthesis of the peptidoglycan in the absence of cadaverine, ATP, UDP-MurNAc-pentapeptide(DAP), and UDP-GlCNAc. The peptidoglycan formed in vitro in the absence of penicillin G was not cross-linked.