Penicillin binding proteins and model transpeptidase activity of the plasma membranes of Streptomyces strains R61 and rimosus

Streptomyces R61 and S. rimosus have an atypical penicillin-binding protein (PBP) pattern characterized by a large amt. of a 25,000-mol.-wt. protein and a small amt. of a 50,000-mol.-wt. protein. The 25,000-mol.-wt. PBP exhibits high thermostability and apparently is the membrane-bound enzyme which catalyzes the model transpeptidase reaction in which Ac2-L-Lys-D-Ala-D-Ala serves as the carbonyl donor and Gly-Gly as the amino acceptor. Whether the thermolabile 50,000-mol.-wt. PBP is also a transpeptidase and is degraded into small fragments or converted into the 25,000-mol.-wt. PBP is unclear. [on SciFinder(R)]