Mutations in E coli cistrons affecting adhesion to human cells do not abolish Pap pili fiber formation

Abstract

A chromosomal DNA fragment which mediates Pap (pili associated with pyelonephritis) pili formation, mannose-resistant hemagglutination ( MRHA ) and binding to uroepithelial cells has been isolated from the uropathogenic Escherichia coli clinical isolate J96 , and genetically studied. Analysis of polypeptides expressed by the Pap DNA led to detection of a number of polypeptides ranging in mol. wt. from 13 000 to 81 000 daltons. The gene order and transcriptional orientation for four of the corresponding cistrons was: 13 000 ( papB ) 19 500 ( papA , structural gene for the Pap pilus subunit), 81 000 ( papC ) and 28 500 ( papD ). Analyses of a lacZ- papA gene fusion located a promoter upstream from papA within the cloned DNA. Transposon Tn5 insertions in any of these four cistrons decreased or eliminated Pap pili formation. A number of transposon Tn5 mutations were identified in a region distal to papD that expressed normal levels of the papA protein on the cell surface in the form of recognizable pili structures but did not agglutinate human erythrocytes or adhere to uroepithelial cells. This region expressed polypeptides of 15 000, 24 000, 26 000 and 35 000 daltons. This finding shows that Pap pili formation and binding properties can be genetically dissociated.