Yersinia pseudotuberculosis Harbors a Type IV Pilus Gene Cluster That Contributes to Pathogenicity

Abstract

Fimbriae have been shown to play an essential role in the adhesion of pathogenic gram-negative bacteria to host cells. In the enteroinvasive bacterium Yersinia pseudotuberculosis, we characterized a previously unknown 11-kb chromosomal locus involved in the synthesis of type IV pili. The locus consists of 11 open reading frames forming a polycistronic unit and encoding putative Pil proteins, PilLMNOPQRSUVW. When introduced into Escherichia coli, the Y. pseudotuberculosis operon reconstituted bundles of filaments at a pole on the bacterial surface, demonstrating that the pil locus was functional in a heterogenous genetic background. Environmental factors regulated transcription of the Y. pseudotuberculosis operon; in particular, temperature, osmolarity, and oxygen tension were critical cues. Deletion of the type IV pilus gene cluster was associated with a reduction of Y. pseudotuberculosis pathogenicity for mice infected orally. Forty-one percent of Y. pseudotuberculosis strains isolated from human or animal sources harbored the type IV pilus locus. Therefore, the pil locus of Y. pseudotuberculosis might constitute an "adaptation island," permitting the microorganism to colonize a vast reservoir.Type IV pili are appendages emanating from the surfaces of several gram-negative bacteria, including species pathogenic for animals and plants (Actinobacillus pleuropneumoniae, Aeromonas veronii biovar sobria, Aeromonas caviae, Dichelobacter nodosus, Eikenella corrodens, enteropathogenic Escherichia coli [EPEC] and enterotoxigenic E. coli [ETEC], Legionella pneumophila, Moraxella bovis, Neisseria meningitidis, Neisseria gonorrhoeae, Pseudomonas aeruginosa, Salmonella enterica, and Vibrio cholerae) (9,11,12,15,16,18,19,20,21,25,27,40,45,49). These structures, which may be peritrichous or polar on the cell surface, sometimes form bundles and have been implicated in a variety of bacterial functions, including cell adhesion (24), bacteriophage adsorption (17, 19), plasmid transfer (19), and twitching motility, a form of flagellum-independent locomotion (26, 44). Pili are composed of pilin subunits, the primary structures of which are conserved (24). All pilins are produced from prepilin molecules through cleavage of the leader sequence by a prepilin peptidase. There is a long hydrophobic segment (20 to 30 amino acid residues [aa]) at the N-terminal region of the mature pilin protein. Type IV pili are classified into two subclasses, IVA and IVB, on the basis of similarities in the deduced amino acid sequences of prepilins. Type IVA prepilins have a very short leader sequence (5 to 6 aa), and the N-terminal amino acid of the mature pilin is a methylated phenylalanine. Type IVB prepilins tend to have longer signal sequences (13 to 30 aa), and the N-terminal amino acid of the mature protein may be a methionine (methylated in some cases), leucine, tryptophan, or serine. The assembly machinery involved in the formation of fimbriae consists of a set of proteins encoded by genes either scattered throughout the bacterial genome (IVA ...

Analysis of the pilU gene for the prepilin peptidase involved in the biogenesis of type IV pili encoded by plasmid R64

“…2a). Recently, additional biosynthetic systems for type IV pili, involving PilV adhesins, have been found in plasmids such as pO113 (Leyton et al 2003) and pA-DAP, and in genomes such as those of Photorhabdus luminescens (Duchaud et al 2003), Yersinia pseudotuberculosis (Collyn et al 2002) and Salmonella enterica serovar Typhi (Zhang et al 2000). The organization of the genes responsible for the formation of these PilVcontaining type IV pili is similar to that in R64 (Fig.…”

Type IVB piliated Salmonella typhi enhance IL-6 and NF-κB production in human monocytic THP-1 cells through activation of protein kinase C

“…Type IV bundle-forming pili of enteropathogenic Escherichia coli (EPEC) are required for localized adherence and virulence (Klumpp et al, 2001). Yersinia pseudotuberculosis harbors a type IV pilus cluster which contributes to pathogenicity (Collyn et al, 2002). S. typhi was recently identified to contain type IVB pili encoded by a pil operon located in pathogenicity island SPI7 (Parkhill et al, 2001;Pickard et al, 2003).…”

The complete DNA sequence and analysis of the virulence plasmid and of five additional plasmids carried by Shiga toxin-producing Escherichia coli O26:H11 strain H30☆

“…pO26-Vir as well as pSERB1 lack the pilI, pilJ, and pilK genes. There is evidence that these genes may not be required for type IV pilus biogenesis as shown with Yersinia pseudotuberculosis and Salmonella Typhi (Collyn et al, 2002;Zhang et al, 2000b). Sequence comparison between pO26-Vir, pO113, and pSERB1 shows a similar gene orientation and order in the tra region and pilL-pilV.…”