Summary: In , the phosphoenolpyruvate:mannose phosphotransferase system (PTS) transports and concomitantly phosphorylates mannose, glucose, fructose and 2-deoxyglucose. PTS consists of a membrane Enzyme II and two forms of Enzyme III (III) having molecular masses of 38.9 kDa (III ) and 35.2 kDa (III ) respectively. We have previously reported the isolation of spontaneous mutants lacking III , and showed that they exhibited abnormal growth when cultured in mixtures of sugars containing glucose. The mutants also synthesize several cytoplasmic glucose-repressible proteins during growth on glucose and some of them constitutively express a fructose PTS which is induced by fructose in the parental strain. We have now investigated the properties and composition of the cellular envelope of three III -defective mutants (strains A37, B31 and G29) after growth on glucose. The mutants have altered sensitivity to various toxic compounds that interfere with cell-envelope functions. The mutants also exhibited altered membrane-protein profiles when analysed by two-dimensional PAGE and modified total lipid and phosphorus contents and lipid/protein ratio. In one mutant (strain G29), the proportion of the phospholipids separated by TLC was different from the parental strain. Electron microscopy indicated that one mutant (strain A37) possessed more fimbriae than the parental strain. The results suggested that these III -defective mutants were affected in a global regulatory gene controlling several cellular or physiological functions, many of these being related to the cellular envelope.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error