Changes in penicillin-binding proteins during the life cycle of Micromonospora.

The penicillin-binding proteins (PBPs) of Micromonospora were studied. Only one PBP (48,000 mol weight) was found in membranes isolated from primary mycelia, whereas three PBPs were observed in secondary mycelia and designated PBP 1 (89,000 mol weight), PBP2 (69,000) and PBP3 (48,000). Both the unique PBP produced by primary mycelia and PBP3 of secondary mycelia had the same affinity for penicillin which was higher than that of PBP2 and 3. The role of these proteins in the cell life cycle of Micromonospora is discussed.