Colonial variation and fimbriation of Actinobacillus actinomycetemcomitans

Inouye, Tadao; Ohta, Hiroyuki; Kokeguchi, Susumu; Fukui, Kiichi; Kato, Kimiko

doi:10.1016/0378-1097(90)90405-f

Cited by 71 publications

(110 citation statements)

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“…P. Smith, T. Ruiz and K. P. Mintz related to the expression of fimbriae (Inouye et al, 1990). Visualization of individual cells by transmission electron microscopy revealed fimbriae associated with the clinical strain (VT1257, Fig.…”

Section: Colony Morphology Of Transformed Parent and Morc Mutant Strainsmentioning

confidence: 97%

“…This conversion typically arises from point mutations in the promoter region of the tad locus, which includes the fimbrial transport machinery (Wang et al, 2005). Loss of fimbriae is accompanied by an increase in colony size and loss of the star-shaped colony morphology characteristic of fimbriated strains of A. actinomycetemcomitans (Inouye et al, 1990). Afimbriated strains also display reduced surface adherence and do not colonize host tissues as effectively as the fimbriated form (Schreiner et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans

2016

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Fimbrial subunit synthesis, secretion and assembly on the surface of the periodontal pathogen Aggregatibacter actinomycetemcomitans are essential for biofilm formation. A recent quantitative proteomics study employing an afimbriated strain and a developed mutant isogenic for the inner-membrane protein morphogenesis protein C (MorC) revealed that the abundance of the proteins of the fimbrial secretion apparatus in the membrane is dependent on MorC.To investigate further the relationship between MorC and fimbriation, we identified and complemented the defect in fimbriae production in the afimbriated laboratory strain. The transformed strain expressing a plasmid containing genes encoding the WT fimbrial subunit and the prepilin peptidase displayed all of the hallmarks of a fimbriated bacterium including the distinct star-like colony morphology, robust biofilm formation, biofilm architecture composed of discrete microcolonies and the presence of fimbriae. When the identical plasmid was transformed into a morC mutant strain, the bacterium did not display any of the phenotypes of fimbriated strains. Extension of these studies to a naturally fimbriated clinical strain showed that the resulting morC mutant maintained the characteristic colony morphology of fimbriated strains. There was, however, a reduction in the secretion of fimbrial subunits, and fewer fimbriae were observed on the surface of the mutant strain. Furthermore, the morC mutant of the fimbriated strain displayed a significantly altered biofilm microcolony architecture, while maintaining a similar biofilm mass to the parent strain. These results suggest that MorC influences fimbrial secretion and microcolony formation in A. actinomycetemcomitans.

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Section: Colony Morphology Of Transformed Parent and Morc Mutant Strainsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans

2016

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“…Fimbriae have been recognized as one of the colony morphology determinants often associated with freshly isolated rough colonies. Rough A. actinomycetemcomitans strains isolated from periodontitis patients produce colonies with a star-shaped interior structure and possess abundant fimbriae (Inouye et al, 1990;Fine et al, 1999). Rough colonies can convert to a smooth phenotype upon in vitro subculture, and this conversion is accompanied by loss of fimbriae and some adhesiveness (Inouye et al, 1990;Fine et al, 1999).…”

Section: Fimbriaementioning

confidence: 99%

“…Fap, a fimbrial subunit, has been isolated, cloned, and sequenced. This fimbrial subunit is expressed predominantly in fimbriated strains (Inouye et al, 1990). Genetic analysis revealed that this fimbrial gene is next to a gene locus coding for the rough colony-specific proteins, RcpA and RcpB (Haase et al, 1999 (Chen and Wilson,199.…”

Section: Fimbriaementioning

confidence: 99%

Molecular Strategies for Fimbrial Expression and Assembly

Fives-Taylor

2001

Critical Reviews in Oral Biology & Medicine

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Fimbriae or pili are long, filamentous, multimeric macromolecules found on the bacterial cell surface. Bacteria express a diverse array of fimbriae or pili that are involved in bacterial adherence and invasion. Fimbriae can be categorized based on their modes of expression and assembly. Type 1 fimbriae and P pili are distributed peritrichously and translocated to the cell surface by a chaperone/usher pathway. Type 4 pili are located at the pole of the cell and assembled via the type 11 secretion system. Curli fimbriae are coiled surface structures assembled by an extracellular nucleation/precipitation pathway. Fimbriae of oral Gram-negative and Gram-positive bacteria have not been well-studied as compared with the fimbriae of enteric pathogens. Oral pathogens, such as Eikenella corrodens, Actinobacillus actinomycetemcomitans, and Porphyromonas gingivalis, possess fimbriae that have been implicated in bacterial adhesion and invasion. These fimbriae are potential virulence factors in oral infectious processes. A. actinomycetemcomitans and E. corrodens have Type 4-like fimbriae, whereas P. gingivalis displays a unique type of fimbriae. To date, fimbriae of the oral primary colonizers, Actinomyces naeslundii and Streptococcus parasanguis, represent the only fimbriae characterized for any Gram-positive bacteria. The putative major fimbrial subunits, FimA and FimP of A. naeslundii and FapI of S. parasanguis, contain a signal sequence and cell-wall-sorting signal. The presence of extensive dipeptide repeats in FapI makes it unique among fimbrial molecules. Based on experimental data, a nucleation/precipitation pathway is proposed for fimbrial biogenesis of both S. parasanguis and A. naeslundii, although we cannot rule out an alternative covalent linkage model. The model systems described in this review served as a framework for hypotheses for how the known molecular factors of fimbriae on oral bacteria may be expressed and assembled.

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“…Clinical isolates autoaggregate and secrete long, bundled pili (Flp fibrils) (Holt et al, 1980;Scannapieco et al, 1987;Rosan et al, 1988;Inoue et al, 1998;Kachlany et al, 2001b;Henderson et al, 2003;Fine et al, 2006). In vitro A. actinomycetemcomitans can produce rare, stable, nonadherent, and nonaggregative genetic variants that form smooth, large colonies and fail to produce Flp fibrils (Wyss, 1989;Inouye et al, 1990;Fine et al, 1999Fine et al, , 2006Kachlany et al, 2000Kachlany et al, , 2001aHenderson et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

tfoX (sxy)-dependent transformation of Aggregatibacter (Actinobacillus) actinomycetemcomitans

Bhattacharjee

Fine

Figurski

2007

Gene

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AbstracttfoX (sxy) is a regulatory gene needed to turn on competence genes. Aggregatibacter (Actinobacillus) actinomycetemcomitans has a tfoX gene that is important for transformation. We cloned this gene on an IncQ plasmid downstream of the inducible tac promoter. When this plasmid was resident in cells of A. actinomycetemcomitans and tfoX was induced, the cells became competent for transformation. Several strains of A. actinomycetemcomitans, including different serotypes, as well as rough (adherent) and isogenic smooth (nonadherent) forms were tested. Only our two serotype f strains failed to be transformed. With the other strains, we could easily get transformants with extrachromosomal plasmid DNA when closed circular, replicative plasmid carrying an uptake signal sequence (USS) was used. When a replicative plasmid carrying a USS and cloned DNA from the chromosome of A. actinomycetemcomitans was linearized by digestion with a restriction endonuclease or when genomic DNA was used directly, the outcome was allelic exchange. To facilitate allelic exchange, we constructed a suicide plasmid (pMB78) that does not replicate in A. actinomycetemcomitans and carries a region with two inverted copies of a USS. This vector gave allelic exchange in the presence of cloned and induced tfoX easily and without digestion. Using transposon insertions in cloned katA DNA, we found that as little as 78 bp of homology at one of the ends was sufficient for that end to participate in allelic exchange. The cloning and induction of tfoX makes it possible to transform nearly any strain of A. actinomycetemcomitans, and allelic exchange has proven to be important for site-directed mutagenesis.

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Colonial variation and fimbriation of Actinobacillus actinomycetemcomitans

Cited by 71 publications

References 11 publications

Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans

Inner-membrane protein MorC is involved in fimbriae production and biofilm formation in Aggregatibacter actinomycetemcomitans

Molecular Strategies for Fimbrial Expression and Assembly

tfoX (sxy)-dependent transformation of Aggregatibacter (Actinobacillus) actinomycetemcomitans

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