title: VirB2 and VirB5 proteins: specialized adhesins in bacterial type-IV secretion systems?
abstract: Many type-IV secretion systems (T4SSs) of plant and human pathogens assemble a pilus used to inject virulence molecules (effectors) into host target cells. The T4SS of Agrobacterium tumefaciens consists of VirB1-VirB11 and VirD4 proteins. Whether targeting of T4SSs to the host requires a T4SS-adhesin that specifically engages host receptors for delivery of effectors has, until recently, remained unclear. Recent data of Agrobacterium and Helicobacter indicate that two classes of T4SS components, VirB2 and VirB5, might function as adhesins that mediate host-cell targeting through binding to specific host receptors. Here, we discuss this important issue and recent progress in the field.
authors.affiliation: Otto-von-Guericke-Universität Magdeburg, Institut für Medizinische Mikrobiologie, Leipziger Strasse 44, D-39120 Magdeburg, Germany. steffen.backert@med.ovgu.de
authors.forename: Steffen
authors.initials: S
authors.lastname: Backert
authors.forename: Remi
authors.initials: R
authors.lastname: Fronzes
authors.forename: Gabriel
authors.initials: G
authors.lastname: Waksman
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016960:Agrobacterium tumefaciens / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D010861:Fimbriae, Bacterial / Q000378:metabolism; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D006801:Humans; D016023:Integrins / Q000378:metabolism; D008969:Molecular Sequence Data; D010941:Plant Tumors / Q000382:microbiology*; D011485:Protein Binding; D021381:Protein Transport; D016415:Sequence Alignment
chemical_list: D018829:Adhesins, Bacterial; D016023:Integrins