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The SfaXII protein from newborn meningitis E. coli is involved in regulation of motility and type 1 fimbriae expression
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). (Uhlin)
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS).
Department of Medical Microbiology and Immunology, University medical School, Pecs, Hungary.
General Microbiology, Faculty of Biosciences, University of Helsinki, Finland.
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2009 (English)In: Microbial Pathogenesis, ISSN 0882-4010, E-ISSN 1096-1208, Vol. 46, no 5, 243-252 p.Article in journal (Refereed) Published
Abstract [en]

The genomes of pathogenic E. coli may contain several different fimbrial operons. How bacteria regulate and coordinate the choice of fimbrial expression under different circumstances remains largely unanswered. In this report we have investigated the role of the sfaXII gene associated to the SfaII fimbrial determinant in the E. coli isolate IHE3034. sfaXII belongs to a subfamily of genes, the 17kDa genes, located near different fimbrial operons in uropathogenic and newborn meningitis E. coli (NMEC) strains. Using the NMEC isolate IHE3034 and non-pathogenic E. coli strains we found that the sfaXII gene had an inhibitory effect on type 1 fimbriae expression. Down regulation of type 1 fimbriae was exerted at transcriptional level both by inhibiting expression from the fimA promoter and by reducing the frequency of OFF-to-ON switching. The effect of sfaXII on expression of the recombinase FimB that catalyzes OFF to ON switching might explain the described reduction in percentage of ON cells. Moreover, expression of the sfaXII gene strongly influenced motility and flagella production of the NMEC isolate IHE3034. We propose that the sfaXII gene, and presumably other members in the 17kDa gene family, may play a role in the control of virulence related gene expression in pathogenic E. coli.

Place, publisher, year, edition, pages
Elsevier Ltd , 2009. Vol. 46, no 5, 243-252 p.
Keyword [en]
NMEC, Regulation, S fimbriae, Type 1 fimbriae, Motility
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
URN: urn:nbn:se:umu:diva-22286DOI: 10.1016/j.micpath.2009.01.007PubMedID: 19486641OAI: diva2:214300
Available from: 2009-05-05 Created: 2009-05-04 Last updated: 2010-04-07Bibliographically approved
In thesis
1. Pathogenecity-associated genes modulate Escherichia coli adhesion and motility
Open this publication in new window or tab >>Pathogenecity-associated genes modulate Escherichia coli adhesion and motility
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Escherichia coli strains typical of UPEC (uropathogenic E. coli) and NBM (newborn meningitis) isolates carry chromosomally located PAIs (pathogenicity islands) that are absent in non-pathogenic E. coli strains. The PAIs include genes for virulence factors such as toxins and genes coding for specific adhesins and pili/fimbriae formation. Commonly, the gene clusters for such fimbriae in E. coli consist of a set of genes for biogenesis of the actual fimbriae organelles: a chaperone, an usher, the fimbrial subunits, and an adhesin, as well as some regulatory genes. Genetic studies of the fimbrial gene clusters in PAIs containing the pap genes, the prs genes, or the sfa genes led to the discovery of nearby open reading frames coding for putative cytoplasmic 17 kDa proteins — the X genes. Molecular genetic studies of the sfaXII locus in the clinical NMEC isolate IHE3034 have been performed. The results suggested that expression of the sfaXII gene had regulatory functions affecting both type 1 fimbriae expression and the flagella-mediated motility.

Type 1 fimbriae expression was found to be affected at the level of fim operon transcription and a major reason was SfaXII-mediated modulation of expression from the fimB and fimE recombinase genes. Quantification of SfaII-fimbriated bacteria in a comparison between wild type and SfaXII mutant strains gave no indication that the sfaXII gene product also would be affecting expression and/or biogenesis of SfaII fimbriae.

Biomechanical properties of the SfaII fimbriae produced by wild type and the sfaXII mutant IHE3034 were studied using force measuring optical tweezers (FMOT) and compared to other PAI-encoded fimbriae as well as to the type 1 fimbriae encoded on the core chromosome. The FMOT methodology assesses unfolding and refolding properties and we found that S fimbriae had weaker layer-to-layer interactions than both P and type 1 fimbriae, however the unfolding kinetics was slightly faster.

The expression profile and regulation of the sfaXII gene were determined by use of reporter gene fusions and it was found that expression was affected by environmental cues such as pH, osmolarity and temperature. It was also discovered that the nucleoid structuring protein H-NS and the sigma factor RpoS had strong direct or indirect repressive effects on sfaXII gene expression.

Further genomic analysis of the PAI fimbrial operons revealed that in some cases an additional ORF was found between the X genes and the fimbrial adhesion genes. Examination of the sfaII operon in IHE3034 indicated that this new gene, denoted sfaYII, coded for a protein that had the EAL domain motif and thereby could be considered a putative phosphodiesterase involved in controlling the level of cyclic-di-GMP in the bacterial cells.

Place, publisher, year, edition, pages
Umeå: Molekylärbiologi, 2009. 49 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1266
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
urn:nbn:se:umu:diva-22302 (URN)987-91-7264-789-3 (ISBN)
Molekylärbiologi (Medicinska fakulteten), 901 87, Umeå
Public defence
2009-05-28, Major Groove, Byggnad 6L, Institutionen för Molekylärbiologi, Umeå Universitet, Umeå, 10:00 (English)
Available from: 2009-05-15 Created: 2009-05-05 Last updated: 2010-04-07Bibliographically approved

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Sjöström, Annika E.Balsalobre, CarlosUhlin, Bernt Eric
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