Summary: Isoelectric focusing was used to compare the complement of phosphoglucose isomerase isoenzymes in a wild-type strain of and in a strain with a deletion in the structural gene. Deletion of the gene did not result in the absence of the high- isoenzyme I but the low- isoenzyme II was absent. Hence, the isoenzymes must be the products of two genes. If were the sole structural gene its deletion would result in the disappearance of both isoenzymes. After a temperature shift-up a -bearing strain had cell cycle arrested and contained only 8% of the polysaccharide in the wild-type. Phosphoglucose isomerase is required for the synthesis of fructose 6-phosphate (F6-P), a precursor of the cell wall components chitin and mannoprotein (“mannan”), which are a polysaccharide and contain polysaccharide, respectively. Since the mutation confers a temperature-sensitive phosphoglucose isomerase, the likely explanation for cell cycle arrest caused by this mutation is that the defective phosphoglucose isomerase results in a reduction of F6-P and hence an inability to synthesize the mannan and chitin needed for cytokinesis and cell separation. Revertants of a bearing strain were selected for their ability to grow on glucose at 25 °C and this yielded a number of different phenotypes. Amongst the isolates was a strain which had undergone an intragenic reversion at the locus, designated . This mutation permits growth and cell division at 25 °C but results in cell cycle arrest at 36 °C. These results are all consistent with the notion that in there are two genes ( and ) which encode the low- and high- isoenzymes, respectively, of phosphoglucose isomerase and that the two gene products physically interact for activity.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

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