Send to

Choose Destination
Cell. 1994 Feb 11;76(3):577-88.

Methylation patterns in pap regulatory DNA control pyelonephritis-associated pili phase variation in E. coli.

Author information

Department of Pathology, University of Utah Health Sciences Center, Salt Lake City 84132.


We have examined the roles of pap DNA methylation patterns in the regulation of the switch between phase ON and OFF pyelonephritis-associated pili (Pap) expression states in E. coli. Two Dam methyltransferase sites, GATC1028 and GATC1130, were shown previously to be differentially methylated in phase ON versus phase OFF cells. In work presented here, these sites were mutated so that they could not be methylated, and the effects of these mutations on Pap phase variation were examined. Our results show that methylation of GATC1028 blocks formation of the ON state by inhibiting the binding of Lrp and PapI regulatory proteins to this site. Conversely, methylation of GATC1130 is required for the ON state. Evidence indicates that this occurs by the inhibition of binding of Lrp to sites overlapping the pilin promoter. A model describing how the transition between the phase ON and OFF methylation states might occur is presented.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center