Interaction of N-acetylmuramic acid L-alanine amidase with cell wall polymers.

In a previous communication (J. Biol. Chem. (1975) 250, 1676-1682), methods were described for the purification of the N-acetylmuramic acid L-alanine amidase from Bacillus subtilis ATCC 6051 and of a modifier protein which combines stoichiometrically with the enzyme and stimulates the activity approximately 3-fold. A detailed examination of the wall cleavage products obtained in the absence and in the presence of modifier indicates that the major effect of the modifier is not to change the enzyme velocity, but rather to change the pattern of cleavage from a more random pattern, when enzyme alone hydrolyzes the cell wall, to a sequential pattern in the presence of modifier protein. Tight binding of the enzyme to the cell wall and functional interaction with the modifier occur only when cell walls from Bacillus subtilis ATCC 6051 containing or teichoic acid are used as a substrate. We suggest that a general function of cell wall teichoic acids is to act as specific "allosteric" ligands for bacterial cell wall lytic enzymes as has been demonstrated previously in Pneumococci (Tomasz, A., and Westphal, M (1971) Proc. Natl. Acad. Sci. U.S.A. 68, 2627-2630).