CHANGE OF THE QUANTITY OF PENICILLIN-BINDING PROTEINS AND OTHER CYTOPLASMIC AND MEMBRANE PROTEINS BY MUTATIONS OF THE CELL SHAPE-DETERMINATION GENES mreB, mreC, AND mreD OF ESCHERICHIA COLI

Abstract

Single and multiple mutations in the mreB, mreC, and mreD genes of Escherichia coli, which are involved in rod shape determination and the accompanied change in the cell's mecillinam resistance, caused an increase in the quantity of septum-peptidoglycan synthetase penicillin-binding protein (PBP)-3, and more general peptidoglycan synthetase PBP-1B. The mreD mutant, but not the mreB and mreC mutants, showed a decreased growth which could be suppressed by deletion of the total mreBCD-orfEF area on the chromosome. The mre mutations additionally caused a complex nature increase/decrease of several other cytoplasmic and membrane protein quantities. These results suggest that the mreB, mreC, and mreD genes are involved in a complex regulatory mechanism in the process of cell growth, division and shape determination.