The Properties of Sex pili, The Viral Nature of “Conjugal” Genetic Transfer Systems, and Some Possible Approaches to the Control of Bacterial Drug Resistance

Cc, Brinton

doi:10.3109/10408417109104479

Cited by 135 publications

(89 citation statements)

References 109 publications

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“…Later it was proposed that F-pili normally undergo cycles of extension and retraction (14,17,19). The idea that DNA can be conducted from donor to recipient through extended F-pili (10,20) has also received experimental support (21,22).…”

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confidence: 99%

F-pili dynamics by live-cell imaging

Clarke

Maddera

Harris

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

130

139

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Bacteria have evolved numerous mechanisms for cell-cell communication, many of which have important consequences for human health. Among these is conjugation, the direct transfer of DNA from one cell to another. For Gram-negative bacteria, conjugation requires thin, flexible filaments (conjugative pili) that are elaborated by DNA donor cells. The structure, function, and especially the dynamics of conjugative pili are poorly understood. Here, we have applied live-cell imaging to characterize the dynamics of F-pili (conjugative pili encoded by the F plasmid of Escherichia coli). We establish that F-pili normally undergo cycles of extension and retraction in the absence of any obvious triggering event, such as contact with a recipient cell. When made, such contacts are able to survive the shear forces felt by bacteria in liquid media. Our data emphasize the role of F-pilus flexibility both in efficiently sampling a large volume surrounding donor cells in liquid culture and in establishing and maintaining cell-cell contact. Additionally and unexpectedly, we infer that extension and retraction are accompanied by rotation about the long axis of the filament.conjugation ͉ conjugative pilus ͉ extension ͉ retraction A mong Gram-negative bacteria, conjugative DNA transfer is mediated by multicomponent type IV secretion systems commonly encoded by large plasmids (1, 2). By virtue of such activity, these plasmids rapidly spread within bacterial populations, contributing to the dissemination of antibiotic resistance (3) among other traits pertinent to human health (2, 4-6).A hallmark of Gram-negative bacterial cells capable of acting as DNA donors is the presence of surface filaments collectively designated conjugative pili (7). F-pili, characteristic of Escherichia coli carrying the conjugative plasmid F, are helical polymers of one subunit, F-pilin (8). Conjugation commences when the tips of F-pili make contact with recipient cells (9, 10). F-pili tips also bind filamentous DNA bacteriophages, such as M13, whereas icosohedral RNA bacteriophages such as R17 bind along the filament sides (11).Indirect evidence has suggested that F-pili are dynamic structures, capable of both extension and retraction. F-pilus retraction as an essential stage of DNA transfer was first proposed by Marvin and Hohn (12) and by Curtiss (13). Various lines of indirect evidence since then have supported the retraction hypothesis (14-18), although fundamental uncertainties remain. For example, retraction was initially regarded as a triggered event, occurring only when a recipient cell or bacteriophage bound to the filament tip (12). Later it was proposed that F-pili normally undergo cycles of extension and retraction (14,17,19). The idea that DNA can be conducted from donor to recipient through extended F-pili (10, 20) has also received experimental support (21,22).Here, we have applied laser-scanning confocal microscopy to study F-pilus dynamics with living cells. Our results clarify some of the uncertainties surrounding F-pilus function and sugge...

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mentioning

confidence: 99%

F-pili dynamics by live-cell imaging

Clarke

Maddera

Harris

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

130

139

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“…Type I pili of gram-negative bacteria had been determined to be protein [1]. F pili were found to be a conjugated protein, containing two molecules of phosphate and one molecule of JD-glucose covalently attached [2]. Bacterial pili, therefore, were considered to be an assembly of simple or conjugated proteins.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the Chemical and Immunological Properties of the Pili of Three Types of Corynebacterium renale

Kumazawa

Yanagawa

1973

Japanese Journal of Microbiology

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Pili of Corynebacterium renale strains 115 (type I) and 42 (type III) were purified, and compared chemically and immunologically with those of strain 46 (type II). Purification ofthe pili of the two strains was more complicated than that of the pili of strain 46. Pili of the three types of C. renale were dispersed in 1 mm ATP and were thermostable. Stability in antigenicity and morphology in 0.1N HCl and 0.1 N NaOH was different, and the antigenicity of the pili was different among the pili of the three types of C. renale.Recent investigations from our laboratory demonstrated that Corynebacterium renale was classified into three types [8] and strains of the three types possessed pili [9,10]. These were the first reported well-documented examples of pili in gram-positive bacteria. In the preceding paper, the pili of C. renale type II were purified and characterized [3].In the present study pili of the remaining types, I and III of C. renale were purified, and chemical and immunological comparisons were made among the pili of the three types of C. renale. MATERIALS AND METHODSMicroorganisms. C. renale strains 115 (type I), 46 (type II) and 42 (type III) were used. These were strains possessing the most numerous pili in each type. The medium used for strains 115 and 46 was a nutrient agar, pH 7.2, supplemented with 0.5% glucose and 1 % bonitoextract (Kishida Chemicals, Osaka

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“…There is a marked tendency for F pili to form aggregates in liquid suspension after removal from cells (Brinton, 1971). 711 pili do not have this property and isolated filaments lie at random angles on carbon support films (Fig.…”

Section: Dimensions and Morphology Of 71 I Pilimentioning

confidence: 99%

Characterization of Pili Determined by Drug Resistance Plasmids R711b and R778b

Bradley

1977

Journal of General Microbiology

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The bacterial drug resistance plasmids R71 rb and R778b, at present classified in the X incompatibility group, determine pili (designated 71 I) that resemble F pili morphologically. Like F pili, 71 I pili adsorb F-specific filamentous bacteriophages to their tips, though more often in pairs, than singly. However, F-specific RNA-containing bacteriophages are not adsorbed to their sides, and strains carrying the plasmids are resistant to these phages. Pili determined by the only IncFV plasmid F,lac are similar to 711 pili in their phage adsorption properties, but they are serologically different, as are F pili. It is concluded that F, FJac and 71 I pili have basic differences in spite of a morphological resemblance. I N T R O D U C T I O NThis paper describes the results of a search for conjugative pili determined by the bacterial drug resistance plasmids originally assigned to the X incompatibility group (IncX): R6K (Kontomichalou, Mitani & Clowes, rgo), R485 (Hedges et al., I973), R71 rb (Hedges, 1974) and R778b (Hedges, 1974). Whilst R71 I b and R778b both determined filaments with a morphological resemblance to F pili, no pili could be found associated with R6K and R485. Furthermore, strains carrying R71 I b and R778b were sensitive to the F-specific filamentous bacteriophages, but were resistant to the RNA-containing phages. The only other plasmids determining these phage sensitivity patterns are laboratory mutants of the IncFI plasmid F (Silverman et al., 1968;Ohtsubo, Nishimura & Hirota, 1970;Achtman, Willetts & Clark, 1971) and the IncFV plasmid Folac (Falkow & Baron, 1962;Datta, 1975). The latter is not to be confused with Flac which is derived from F. F,lac determines pili morphologically similar to those of F (Brinton, 1965;Lawn et al., 1967) and is unrelated by incompatibility to R71 Ib and R778b (N. Datta, personal communication).This work characterizes the pili determined by R71 I b and R778b and shows that they differ in some respects from both F and Folac pili. A detailed study of any one aspect was not intended; the objective was to indicate areas of general interest. FoZac pili are only included in a few of the experiments described since a more detailed description of them (encoded by a derepressed FJac plasmid constructed by N. Willetts) is being carried out elsewhereThere is now some doubt concerning the classification of R711b and R778b (resistance determined to Km and Su respectively). Both were described as belonging to the incompatibility group X (IncX): R778b was incompatible with the multicopy plasmid R6K (Kontomichalou et al., 1970; designated the prototype IncX plasmid by Hedges et al., 1973), and R711b was incompatible with R778b (Hedges, 1974). Subsequently it has been shown that R711b and R6K are not incompatible; therefore these three plasmids do not all belong to one group on the basis of incompatibility (Datta, 1975; N. Datta, personal communication type I pili absent. METHODS Bacterialstruins andgrowth media.The strains used are listed in Table I. Difco Nutrient Broth was gen...

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The Properties of Sex pili, The Viral Nature of “Conjugal” Genetic Transfer Systems, and Some Possible Approaches to the Control of Bacterial Drug Resistance

Cited by 135 publications

References 109 publications

F-pili dynamics by live-cell imaging

F-pili dynamics by live-cell imaging

Comparison of the Chemical and Immunological Properties of the Pili of Three Types of Corynebacterium renale

Characterization of Pili Determined by Drug Resistance Plasmids R711b and R778b

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