Ian C. Blomfield

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Expression of type 1 fimbriae in Escherichia coli K-12 is phase variable and associated with the inversion of a short DNA element (switch). The fim switch requires either fimB (on-to-off or off-to-on switching) or fimE (on-to-off switching only) and is affected by the global regulators leucine-responsive regulatory protein (Lrp), integration host factor(More)
The site-specific DNA inversion that controls phase variation of type 1 fimbriation in E. coli is catalysed by two recombinases, FimB and FimE. Efficient inversion by either recombinase also requires the leucine-responsive regulatory protein (Lrp). In addition, FimB recombination is stimulated by the integration host factor (IHF). The effect of IHF on FimE(More)
To facilitate efficient allelic exchange of genetic information into a wild-type strain background, we improved upon and merged approaches using a temperature-sensitive plasmid and a counter-selectable marker in the chromosome. We first constructed intermediate strains of Escherichia coli K12 in which we replaced wild-type chromosomal sequences, at either(More)
We have used Southern hybridization analysis to characterize the extent of fim homology in recognized type 1 fimbriae mutants of Escherichia coli K12, including strains HB101, P678-54, and VL584. We have found extensive homology in strain HB101, and confirm that P678-54 lacks the majority of fim DNA. Strain VL584 contains a deletion of the entire fim(More)
The phase variation of type 1 fimbriae in Escherichia coli is associated with the site-specific inversion of a short DNA element. Recombination at fim requires fimB and fimE, and their products are considered to be the fim recombinases. In this study, FimB and FimE were overproduced and extracts containing the proteins were shown to (i) bind to and (ii)(More)
The ability of bacterial pathogens to bind to the host mucosa is a critical step in the pathogenesis of many bacterial infections and, for Escherichia coli, a large number of different fimbrial adhesins have been implicated as virulence factors. In this chapter, our current understanding of the regulatory mechanisms that control the expression of two of the(More)
Bacterial-host attachment by means of bacterial adhesins is a key step in host colonization. Phase variation (reversible on-off switching) of the type 1 fimbrial adhesin of Escherichia coli involves a DNA inversion catalyzed by FimB (switching in either direction) or FimE (mainly on-to-off switching). fimB is separated from the divergent yjhATS operon by a(More)
The phase variation of type 1 fimbriation in Escherichia coli is associated with the inversion of a short DNA element. This element (switch) acts in cis to control transcription of fimA, the major fimbrial subunit gene. Thus, fimA is transcribed when the switch is in one orientation (the on orientation) but not the other (the off orientation). The fim(More)
Evidence obtained with an improved in vivo assay of fimbrial phase variation in Escherichia coli supported a revised understanding of the roles of fimB and fimE in the site-specific DNA rearrangement with which they are associated. A previously proposed model argued that fimB and fimE play antagonistic, unidirectional roles in regulating the orientation of(More)
The leucine-responsive regulatory protein (Lrp) is a global regulator that controls the expression of numerous operons in Escherichia coli. Lrp can act as a repressor or as an activator of transcription with its effects being potentiated, repressed or unaffected by the presence of exogenous leucine. The phase variation of type 1 fimbria in E. coli provides(More)