Disease relevance of fimB

• Two regulatory fim genes, fimB and fimE, control the phase variation of type 1 fimbriae in Escherichia coli [1].
• The Vibrio cholerae genome contains a 5.4-kb pil gene cluster that resembles the Aeromonas hydrophila tap gene cluster and other type IV-A pilus assembly operons [2].
• In spite of the unusual phage sensitivity pattern, FA2 lacked the ability to produce functional polar pili (pil) and was incapable of twitching motility (twt) [3].
• Other regions that are conserved in variant pilin polypeptides from Neisseria gonorrhoeae are conserved at the amino acid level in the class I meningococcal pilin but the coding DNA contains numerous base substitutions when compared with the equivalent gonococcal pil sequence [4].
• A Haemophilus influenzae DNA library was prepared in the vector lambda EMBL3, and recombinant phage were screened for the pilin gene (pil) using a synthetic oligonucleotide [5].

High impact information on fimB

• The fimB and fimE proteins direct the phase switch into the 'on' and 'off' position, respectively [1].
• Short ( approximately 28 bp) cis-active elements (regions 1 and 2) close to yjhA stimulate fimB expression and are required for sialic acid (Neu(5)Ac) sensitivity of its expression [El-Labany, S., Sohanpal, B. K., Lahooti, M., Akerman, R. & Blomfield, I. C. (2003) Mol. Microbiol. 49, 1109-1118] [6].
• Integrated regulatory responses of fimB to N-acetylneuraminic (sialic) acid and GlcNAc in Escherichia coli K-12 [6].
• The fimB gene is separated from the divergently transcribed yjhATS operon by a large (1.4 kbp) intergenic region of unknown function [7].
• Here, we show that fimB expression is regulated by multiple cis-active sequences that lie far upstream (>600 bp) of the transcription start sites for the recombinase gene [7].

Biological context of fimB

• Dimethyl sulphoxide (DMS)-mediated methylation of DNA at the 9 bp inverted repeats, which flank the invertible element, was found to vary in the presence and absence of functional fimB [8].
• Switches from a nonmotile to a motile phenotype and from a fim on to off genotype were observed in fim ON CFT073 DeltafimBE ipuAB ipbA mutants when ipuA or fimB was provided in trans [9].
• In gel mobility shift assays with purified H-NS, we have also shown that H-NS bound directly and cooperatively to the fimB promoter region with greater affinity than for any other known H-NS-regulated gene [10].
• The second step of the exchange procedure introduced either wild-type or mutant alleles of fimB and/or fimE into the chromosome of the intermediate strains [11].
• E. coli F-18(pPR633) contains essentially the same plasmid minus the fimB gene and in L-broth about 30% of the cells express type 1 fimbriae [12].

Anatomical context of fimB

• Previous studies have shown that products of several ancillary pil genes are required for organelle biogenesis but of these only PilQ, a member of the GspD protein family, is a component of the outer membrane [13].
• Urinary tract isolates differed from fecal isolates by a low incidence of type 1 adhesin expression among pil probe-positive isolates. hly-related sequences were only detected in pap probe-positive isolates [14].
• Furthermore, all VFs except pil were significantly more frequently detected in strains isolated from urine of animals with cystitis than in those isolated from feces of healthy humans [15].

Associations of fimB with chemical compounds

• Both fimE-promoted switching and fimB-promoted switching are stimulated by the amino acids alanine, isoleucine, leucine, and valine, and this regulation requires lrp [16].
• The DMS reactivity profile at the left-hand inverted repeat was similar with single or multicopy fimB [8].
• Isolates with the pil operon (the genome for type 1 fimbriae) from episodes lasting greater than 1 week expressed mannose-sensitive hemagglutination more frequently (P = 0.011) than pil-positive isolates from episodes of less than or equal to 1 week [17].
• The pil genes were mapped close to the gene clusters thr and leu controlling the biosynthesis of threonine and leucine, respectively [18].
• When the pil operon is placed under the control of a tac or lac promoter-operator sequence, the bacterial cells can be induced to form flocs by adding isopropyl-beta-D-thiogalactopyranoside to the culture medium [19].

Other interactions of fimB

• This effect was more pronounced in high-osmolarity acidic media; fimB and fimA expression decreased fivefold in growth media containing 800 mM NaCl compared to expression in growth media without added NaCl [20].
• The fim gene cluster of strain MT78 was cloned and its sequence was determined in a region spanning upstream of fimB to the beginning of fimD [21].

Analytical, diagnostic and therapeutic context of fimB

• Transcription starting from two of the sites (P1 and P2) would produce an mRNA that approximates the transcript size of fimB previously detected by Northern blot hybridizations [22].

References