title: The structure of VgrG1 from Pseudomonas aeruginosa, the needle tip of the bacterial type VI secretion system.
abstract: The type VI secretion system (T6SS) is a mechanism that is commonly used by pathogenic bacteria to infect host cells and for survival in competitive environments. This system assembles on a core baseplate and elongates like a phage puncturing device; it is thought to penetrate the target membrane and deliver effectors into the host or competing bacteria. Valine-glycine repeat protein G1 (VgrG1) forms the spike at the tip of the elongating tube formed by haemolysin co-regulated protein 1 (Hcp1); it is structurally similar to the T4 phage (gp27)3-(gp5)3 puncturing complex. Here, the crystal structure of full-length VgrG1 from Pseudomonas aeruginosa is reported at a resolution of 2.0 Å, which through a trimeric arrangement generates a needle-like shape composed of two main parts, the head and the spike, connected via a small neck region. The structure reveals several remarkable structural features pointing to the possible roles of the two main segments of VgrG1: the head as a scaffold cargo domain and the β-roll spike with implications in the cell-membrane puncturing process and as a carrier of cognate toxins.
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas (CIB), CSIC, Calle de Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Spínola-Amilibia
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas (CIB), CSIC, Calle de Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Davó-Siguero
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas (CIB), CSIC, Calle de Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Federico M
authors.initials: FM
authors.lastname: Ruiz
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas (CIB), CSIC, Calle de Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Santillana
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas (CIB), CSIC, Calle de Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Medrano
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas (CIB), CSIC, Calle de Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Romero
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D011487:Protein Conformation; D055503:Protein Multimerization; D011550:Pseudomonas aeruginosa / Q000737:chemistry*; D000069376:Type VI Secretion Systems / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D000069376:Type VI Secretion Systems
keywords: P. aeruginosa; T6SS; VgrG1; X-ray crystallography; effectors; infection; secretion; structure; toxins; virulence