Adhesive mechanism of different Salmonella fimbrial adhesins

Recent Advances in Our Understanding of the Diversity and Roles of Chaperone-Usher Fimbriae in Facilitating Salmonella Host and Tissue Tropism

“…Since the discovery of fimbriae in Escherichia coli in 1955, at least 39 different fimbriae have been described in Salmonella ( Yue et al, 2012 ; Desai et al, 2013 ; Aviv et al, 2017 ; Cheng et al, 2019 ; Rehman et al, 2019 ). Fimbriae belong to four general categories depending on their morphology, function, or assembly pathway: (i) F pili, (ii) type IV fimbriae, (iii) curli, and (iv) chaperone-usher pathway fimbriae (reviewed in [ Nuccio and Bäumler, 2007 )].…”

“…Fimbriae belong to four general categories depending on their morphology, function, or assembly pathway: (i) F pili, (ii) type IV fimbriae, (iii) curli, and (iv) chaperone-usher pathway fimbriae (reviewed in [ Nuccio and Bäumler, 2007 )]. Fimbriae of the chaperone-usher pathway represent the majority of fimbriae encoded by Salmonella ( Nuccio and Bäumler, 2007 ; Rehman et al, 2019 ), and are therefore the focus of our discussion. Chaperone-usher pathway fimbriae, so named because these fimbriae utilize one or more chaperones to transfer folded fimbrial subunits to the usher protein (an integral outer membrane protein) for translocation across the outer membrane ( Figure 1A ), are categorized phylogenetically based on sequence conservation of the usher protein ( Nuccio and Bäumler, 2007 ; Thanassi et al, 2007 ).…”

“…In 2007, Nuccio and Bäumler proposed the current classification scheme for chaperone-usher pathway fimbriae, which groups chaperone-usher fimbriae into three general categories based on the phylogenetic relatedness of the usher protein: (i) alternate, or α-fimbriae, (ii) classical, or β-, γ-, κ-, π-fimbriae; (iii) and archaic, or σ-fimbriae ( Nuccio and Bäumler, 2007 ). Members of the γ-fimbriae are further sub-divided into classes γ 1 through γ 4 ( Nuccio and Bäumler, 2007 ), although γ 2 fimbriae have not been identified in Salmonella ( Yue et al, 2012 ; Rehman et al, 2019 ). Among the 36 known chaperone-usher fimbriae produced by Salmonella , the alternative and archaic fimbriae include just one member each ( Yue et al, 2012 ), and the remaining 34 represent members of the classical fimbriae with 23 belonging to the γ-fimbriae ( Figure 1B ) ( Desai et al, 2013 ; Rehman et al, 2019 ).…”

Role of Bacterial Cytoskeleton and Other Apparatuses in Cell Communication

“…But later, with the help of serological tests, genetic relatedness of fimbrial antigens was identified and fimbriae were further classified into 3 different types based upon their assembly pathways. The three assembly pathways which lead to multiple types of fimbriae are chaperon-usher (CU), nucleation-precipitation (N/P), and Type IV fimbriae (Rehman et al, 2019). SEF 14 and SEF 21 are the two comprehensively studied Type I fimbriae of Salmonella enteritidis (Müller et al, 1991).…”

“…Fimbriae though functionally seem similar to fibrils but are ultrastructurally as well as biochemically different entities. Fimbriae structures ranges in between 0.5 and 10 μm length and 2–8 nm width whereas fibrils lengths vary in different strains ( Handley, 1990 ; Rehman et al, 2019 ). Presence of fimbriae in some cases provides strong indication toward bacterial virulence.…”