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At least 19 recordsLinked to original sources

PubMed1979

The function of fimbriae in Myxococcus xanthus. I. Purification and properties of M. xanthus fimbriae.

Myxococcus xanthus fimbriae have been purified and characterized as part of a study of the function of fimbriae in this prokaryote. Myxococcus xanthus produced two types of fimbriae, termed flaccid (F) and rigid (R) on the basis of electron microscopy. F and R fimbriae differed slightly in their response to pH and freeze-thaw regimes but were similar in their resistance to hydrolytic enzymes, amino acid composition, molecular weight, carbohydrate content, and antigenic determinants. Although the precise relationship between F and R fimbriae is unknown, the possibility is considered that F fimbriae might represent a "contracted" form of the R type. Studies designed to determine fimbriae function in M. xanthus are described in an accompanying report.

Amino Acids↗

PubMed1979

The function of fimbriae in Myxococcus xanthus. II. The role of fimbriae in cell-cell interactions.

Anti-fimbriae antiserum specifically inhibited swarming but no gliding motility per se in Myxococcus xanthus. However, formation of motile aggregates on agar and clumps in liquid media correlated with the presence of fimbriae. Ethylenediaminetetraacetic acid which inhibited swarming also inhibited fimbriae formation. Direct electron-microscopic observations revealed that fimbriae establish contact with apposing cell surfaces. Intact but not depolymerized fimbriae exhibited hemagglutination activity against guinea pig erythrocytes. This activity was inhibited by mannose, N-acetyl-D-galactosamine, and to a lesser degree by fructose, raffinose, melibiose, and alpha-methyl-D-mannoside. It is concluded that fimbriae are organelles which function to establish and maintain intercellular contacts, perhaps by a lectin-like function, during the coordinated movement of cell aggregates' (swarming) in myxobacteria. This hypothesis is supported by the observations of other workers that genes determining movement of cells in groups also control fimbriation in M. xanthus.

Acetylglucosamine↗

PubMed1975

Fungal fimbriae. I. Structure, origin, and synthesis.

Fine hair-like appendages on the cell walls of the another smut Ustilago violacea are described. These hairs are termed fimbriae because of their close similarity to the fimbriae (pili) found on certain Gram-negative bacteria. Cells of U. violacea may carry more than 200 fimbriae varying in length from about 0.5 mum to over 10 mum, and having a diameter of about 60-70 A. Some fimbriae produce knobs similar to those found on bacterial sex fimbriae. Log-phase cells are the most densely fimbriated, while stationary phase cells are devoid of fimbriae. The cells can be defimbriated by sonication, high-speed agitation, or centrifugation through a 40% sucrose solution. The fimbriae can regenerate in these defimbriated cells in about 1 h. This regeneration is inhibited by both cycloheximide and rifampin, but not by chloramphenicol and therefore appears to depend on de novo protein synthesis on cytoplasmic ribosomes. Similar long fimbriae are found on U. maydis and Leucosporidium (Candida) scottii. Short fimbriae, about 0.5 mum long, were found on all the other species of yeast-like fungi examined (Rhodotorula, Saccharomyces, Schizosaccharomyces, Hansenula, Lipomyces, Nadsonia, and Torulopsis spp.).

Cell Wall↗

PubMed2025

Identification of OxyR as an activator of type 1 fimbriae (fim) in Salmonella enterica serovar Typhi.

Salmonella enterica serovar Typhi (S. Typhi) encodes 14 fimbrial gene clusters, including the mannose-binding type 1 fimbriae known as Fim. Type 1 fimbriae have been implicated in biofilm formation and adhesion to host cells in Salmonella. However, their regulation in S. Typhi remains largely unknown. To identify genes affecting the regulation of fim in S. Typhi, we employed both a targeted and a genome-wide transposon-based screening approach. Overall, we identified 18 potential regulators of fim expression: 10 activators and 8 repressors. Two genes involved in the electron transport chain, yqiC and ndh, which encode the type II NADH dehydrogenase NDH-2, were identified. Both YqiC and NDH-2 contribute to the production of reactive oxygen species, prompting an investigation into the roles of oxidative stress response regulators OxyR and SoxR. We found that only OxyR regulates fim expression, which was specific to S. Typhi. OxyR acts by directly binding to the fimA promoter region. This study paves the way for future development of anti-adhesion strategies through the identification of 14 novel regulators for the most prominent fimbriae of S. Typhi.IMPORTANCEAdhesion mediated by fimbriae is one of the critical steps in the infection process. Therefore, it is essential to better understand the regulation of type 1 fimbriae (fim) in the human-specific pathogen Salmonella enterica serovar Typhi, the etiologic agent of typhoid fever. In this study, we identified 18 distinct mutants with altered regulation of fim. Furthermore, we confirmed that the DNA-binding protein OxyR directly regulates fim expression. Importantly, we also demonstrated regulatory differences in fim expression between S. Typhi and S. Typhimurium, as six of the genes identified altering fim expression in S. Typhi either did not affect fim expression in S. Typhimurium or had the contrary effect. This highlights fundamental differences between these serovars and emphasizes the need to investigate and compare aspects of gene regulation in S. Typhi.

Salmonella typhi↗

PubMed1976

Epithelial cell binding of group A streptococci by lipoteichoic acid on fimbriae denuded of M protein.

Group A streptococci were treated with various enzymatic and chemical agents in an attempt to dissociate the type-specific M protein from intact surface "fimbriae." Mild peptic digestion at pH 5.8, which was previously shown to extract serologically active M antigen from intact streptococci had little visible effect on the fimbriae even though virtually all of the M protein was removed as demonstrated by (a) increased susceptibility to phagocytosis, (b) lack of opsonic effect of homologous M antibody on the treated streptococci, and (c) loss of HCl-extractable M protein. These fimbriated streptococci which lacked M protein adhered to human oral mucosal cells equally as well as untreated, fimbriated organisms which retained their M protein. Removal of both fimbriae and M protein by digesting organisms with HCL at pH 2.0 at 94 degrees C. or with trypsin abolished their ability to bind mucosal cells. Electron microscopy of streptococci bound to epithelial cells demonstrated fimbriae radiating from the surface of the organisms to the membrane of the epithelial cells. It is apparent, therefore, that the determinants of streptococcal fimbriae involved in resistance to phagocytosis can be dissociated from those involved in epithelial cell binding. These results are consistent with our previous studies which suggested that fatty acids ester linked with glycerol teichoic acid rather than M protein of streptococci binds the organisms to epithelial cells.

Antigen-Antibody Reactions↗

PubMed1977

Serologic relationship of fimbriae among Enterobacteriaceae.

The existence of serological relationship of fimbriae among serotypes of the same genus and among genera of Enterobacteriaceae was determined by agglutination and absorption procedures. It was found that fimbriae of different serotypes of the same genus and among the genera a) Escherichia, Shigella and Klebsiella, and b) Salmonella, Arizona and Citrobacter were more or less antigentically related. No relationship was found among fimbriae of the Edwardsiella, Enterobacter, Hafnia, Serratia, Proteus and Providencia. It was also found that in Klebsiella, MS and MR fimbriae differed antigenically. On the basis of the results obtained nine antigentically distinct types of fimbriae were distinguished.

Antigens, Bacterial↗

PubMed1976

Examination of the envelope antigen K1 in Yersinia enterocolitica which was identified as fimbriae.

The envelope antigen K1 found in the majority of Yersinia enterocolica (Y. ent.) strains belonging to the O group 10 as described by WAUTERS, was re-examined under the electron microscope, and identified as being fimbriae. These fimbriae envelop the bacterial cell with a dense fringe. Single filaments show a width of 2.5 to 1.7 nm whilst their length is variable, often many times the size of the bacterial cell. Fimbriated Y. ent. cultures do not form pellicle, and the haemagglutination test is negative. They are O and fimbriae agglutinable. Test results for the acknowledged 3 antigenic differences, i.e. agglutinability, agglutinin-binding capacity and agglutinogenic capacity showed that: 1. there is a certain thermo-lability as to the agglutinability. For its total suppression, half-an-hour's boiling at 120 degrees C of the culture fim+ is necessary. Chemical treatment of such a culture hardly impairs the agglutinability of fimbriae. 2. the agglutinin-binding (= absorbing) capacity of the fimbrial antigen is little affected by continuous heating, even up to 3 hrs. However, at least half-an-hour's boiling at 120 degrees C or alternatively chemical treatment with 50% alcohol or nHC1 practically destroys this ability. 3. The heating process has a significant and progressive effect on the agglutinogenic capacity of the Y. ent. fimbriae which is destroyed irrevocably after 30 mins. boiling at 120 degrees C. Chemical treatment hardly affects this character. It is recommended to use a formalised culture Y. ent. fim+ for the preparation of a specific Y. ent. fimbrial serum. For the elimination of O antibodies, this antiserum should be absorbed with a strain fim- of the same O group. Provided the strain was incubated at 37 degrees C, no H absorption is required, because Y. ent. strains do not form flagella at that incubation temperature.

Agglutination Tests↗

PubMed1977

Commissural projection to the amygdala thourgh the fimbria fornix system in the cat.

Single shock stimulations have been applied stereotaxically and bilaterally in the region of the caudo-thalamic groove of the cat. These stimulations elicit diphasic potentials in the amygdala. Using combined methods of stimulation and lesion, it has been demonstrated that these electrical responses are due to the excitation of fibers projecting rostrally in the lateral border of the contralateral fimbria and caudally in the homologous part of the homolateral fimbria. A commissural path has been identified in the rostral part of the fimbria-fornix. Analysis of the experimental data has shown that the projection system consists of a discrete bundle of fibers which probably reaches the amygdala directly, in the dorsal part of the basal nucleus. The length of the explored portion of this pathway has been measured. The calculated conduction velocity of this amygdalopetal commissural component of the fimbria is 4.5 m/sec.

Amygdala↗

PubMed1977

Fimbriae and haemagglutinating properties in Edwardsiella and Levinea.

Using the haemagglutinating procedure, the presence of fimbriae was revealed in all 34 Edwardsiella strains tested and in 3 Levinea strains out of 17 examined. The great majority of fimbriate Edwardsiella strains caused haemagglutination of MR type; only two strains of Edwardsiella and all fimbriate strains of Levinea brought about haemagglutination of MS type. All the strains exhibited a similar spectrum of haemagglutinating activity when they were tested against red cells of various animal species. Under the electron microscope MR fimbriae of Edwardsiella were found to be thicker than MS fimbriae (6.5 nm and 6.0 nm respectively). MS fimbriae of Levinea had 6.5 nm in diameter.

Animals↗

PubMed2026

A posttranslational modification of fimbriae drives pathogenicity in Klebsiella pneumoniae.

Antimicrobial resistance is a severe public health burden. Especially concerning are multidrug resistant (MDR) infections, which restrict treatment options and significantly increase mortality risk. A major cause of MDR infections worldwide is carbapenem-resistant Klebsiella pneumoniae (CRKp). The predominant CRKp sequence type worldwide is ST258. However, the factors underlying ST258's epidemic success are not well defined. Genomic analyses of clinical isolates of CRKp have found that the two-component regulatory system CrrAB is a genomic feature of ST258, suggesting that it may contribute to its global dominance. Despite this, the molecular details underpinning CrrAB's contribution to ST258 Kp biology and pathogenicity are poorly understood. We used RNA-sequencing to identify the regulon of CrrA and found that CrrAB induces the expression of a gene, encoding Crr-regulated fimbriae modifying protein (CfmP), that is essential for pathogenesis driven by this two-component system. We performed mass spectrometry analyses of fimbriae purified from Kp expressing or lacking cfmP and found that CfmP induces a novel oxidation to a histidine residue in the major pilin subunit of fimbriae, FimA. We demonstrate that this oxidation significantly increases host cell adhesion and high bacterial loads within the host. CrrAB also drives high antibiotic resistance in CRKp. Thus, our results place CrrAB at the intersection of pathogenicity and antibiotic resistance supporting its function as an important regulatory system driving the global dominance of ST258.

Klebsiella pneumoniae↗

PubMed1978

Fimbriae of Actinomyces viscosus t14v: their relationship to the virulence-associated antigen and to coaggregation with Streptococcus sanguis 34.

1) Fimbriae from A. viscosus T14V may be similar to those found on other bacteria. 2) The antigenic difference between virulent and avirulent A. viscosus T14 appears to be of a quantitative rather than a qualitative nature and is related to fimbriae and not to the cell wall polysaccharide. 3) Coaggregation between A. viscosus T14V and S. sanguis 34 is mediated by fimbriae on the former which have specificity for beta-linked galactosyl residues.

Actinomyces↗

PubMed1979

Location of binding sites on common type 1 fimbriae from Escherichia coli.

Common type 1 fimbriae were isolated from Escherichia coli and their length distribution profile was determined before and after treatment with ultrasound. As fimbriae were shortened, so their haemagglutinating capacity decreased, but their ability to bind to erythrocytes did not decrease to the same extent. Isolated fimbriae did not agglutinate inside-out vesicles prepared from horse erythrocytes or liposomes, suggesting that the binding mechanism was not based on non-specific hydrophobic interactions. The results support a lateral rather than a terminal location for the fimbrial binding site responsible for haemagglutination.

Binding Sites↗

PubMed1979

Dispensability of fimbriae: ovum pickup by tubal fistulas in the rabbit.

This study was carried out to test the general belief that fimbriae should be considered almost indispensable to ovum capture. Surgical procedures, including resection of the mesotubarium superius and infundibulum tubae together with the creation of a fistula, are described. An attempt to enhance tubal patency by temporarily using estrogens is discussed. Ovum pickup was determined by flushing both tubes and the uterus 2 days following ovulation induction. The prior use of estrogens did not appear to have increased subsequent ovum pickup in control animals; on the contrary, it even seems possible that estrogens had negatively influenced pickup by the fistulas. With five fistulas, however, three recovered ova represented a pickup rate of 7% to 14% of all ova available following one human chorionic gonadotropin-induced ovulation. These figures suggest that ovum pickup by terminal ampullary fistulas is not negligible; they might indicate that absence of fimbriae offers neither good protection against pregnancy following sterilization nor a hopeless prognosis for fimbriectomy reversal when a distal patent tube is present.

Animals↗

PubMed1978

Antigenic characterisitcs of Moraxella nonliquefaciens fimbriae in double immunodiffusion.

Rabbit antisera against purified fimbriae (pili) from Moraxella nonliquefaciens detected three fimbrial antigenic components, one or two of which appeared to be present in other fimbriated strains of M. nonliquefaciens and the closely related M. bovis. Maximal precipitation with the antisera required some denaturation of the antigen. Ultrasonication, repeated freeze-thawing, heating, and agents like KBr, NaSCN and urea were effective in liberating the antigen in diffusible forms. The morphology of the fimbriae was altered by heat treatment in 1 M KBr.

Antigens, Bacterial↗

PubMed1979

Spatial memory deficit following fimbria-fornix lesions: independent of time for stimulus processing.

The present experiment examined the possible role of stimulus processing time in the spatial memory deficit found following fimbria-fornix lesions in rats. Rats were trained preoperatively on a radial arm maze in a procedure that placed them at the end of each arm and confined them there for 30 seconds. This confinement period was markedly longer than the few seconds the rats normally spend there in the usual test procedure. Rats with fimbria-fornix lesions performed no better than expected by chance on the first choice after placements. Although performance on subsequent choices was above chance, this was due to a strong turning pattern; when this pattern was interrupted, performance was no greater than that expected by chance on all choices. These data demonstrate that the deficit in the radial arm maze resulted primarily from a difficulty in spatial memory, rather than from an insufficient time for processing stimulus information.

Animals↗

PubMed2026

Illicium verum polysaccharide targets fimbriae and flagella to disrupt biofilm and inhibit multidrug-resistant Escherichia coli proliferation.

The widespread dissemination of multidrug-resistant (MDR) E. coli has led to a decrease in the efficacy of antibiotics, posing severe challenges to clinical anti-infective therapy. Owing to their safety, multitarget activities, and low risk of inducing drug resistance, plant polysaccharides represent a promising alternative strategy. In this study, an acidic polysaccharide (IVP-3) was isolated and purified from the medicinal and edible plant Illicium verum, and it was found to inhibit MDR E. coli colonization by disrupting its biofilm. The Mw of IVP-3 was determined to be 35.566 kDa. Its backbone consists of →4)-α-D-GalpA-6-OMe-(1→, →4)-α-D-GalpA-(1→, →4)-β-D-Galp-(1→, and →3,4)-α-D-GalpA-(1 → residues, whereas the branched chain is composed of α-L-Araf-(1 → 5)-α-L-Araf-(1 → attached to the O-5 position of →2,5)-α-L-Araf-(1→, which is further linked to the O-3 position of the backbone. Mechanistically, IVP-3 disrupts the structure of fimbriae and flagella, inhibits bacterial motility, effectively prevents initial biofilm adhesion, and eradicates preformed mature biofilms. Additionally, IVP-3 damages cell membrane integrity, disrupts the proton motive force, and induces energy metabolism disorder, efflux pump inhibition, and oxidative stress, ultimately leading to bacterial lysis. This study provides a theoretical basis for the development of natural antibacterial agents targeting MDR E. coli biofilms and for the high-value utilization of Illicium verum.

Biofilms↗

PubMed1978

Cyclic AMP-dependent synthesis of fimbriae in Salmonella typhimurium: effects of cya and pts mutations.

Synthesis of bacterial fimbriae (group 1, subtype 1) was shown to be dependent on cyclic AMP and was subject to catabolite repression by many carbohydrates. Mutations in the genes coding for the energy-coupling protein constituents of the phosphoenolpyruvate:sugar phosphotransferase system prevented repression of fimbrial production by the sugar substrates of this enzyme system.

Carbohydrates↗

PubMed1979

Fimbriae of Escherichia coli K-12 strain AW405 and related bacteria.

Fimbriate strains of Escherichia coli K-12 of the AW405 series agglutinated erythrocytes of several animal species. The hemagglutination was mannose senstivie, and the fimbriae were type 1. When cultured for extended periods in static broths, they did not form fimbrial pellicles but formed thick, nonfimbrial pellicles, the appearance of which was not associated with the selective outgrowth of fimbriate-phase bacteria.

Aerobiosis↗