title: Effects of lng Mutations on LngA Expression, Processing, and CS21 Assembly in Enterotoxigenic Escherichia coli E9034A.
abstract: Enterotoxigenic Escherichia coli (ETEC) is a major cause of morbidity in children under 5 years of age in low- and middle-income countries and a leading cause of traveler's diarrhea worldwide. The ability of ETEC to colonize the intestinal epithelium is mediated by fimbrial adhesins, such as CS21 (Longus). This adhesin is a type IVb pilus involved in adherence to intestinal cells in vitro and bacterial self-aggregation. Fourteen open reading frames have been proposed to be involved in CS21 assembly, hitherto only the lngA and lngB genes, coding for the major (LngA) and minor (LngB) structural subunit, have been characterized. In this study, we investigated the role of the LngA, LngB, LngC, LngD, LngH, and LngP proteins in the assembly of CS21 in ETEC strain E9034A. The deletion of the lngA, lngB, lngC, lngD, lngH, or lngP genes, abolished CS21 assembly in ETEC strain E9034A and the adherence to HT-29 cells was reduced 90%, compared to wild-type strain. Subcellular localization prediction of CS21 proteins was similar to other well-known type IV pili homologs. We showed that LngP is the prepilin peptidase of LngA, and that ETEC strain E9034A has another peptidase capable of processing LngA, although with less efficiency. Additionally, we present immuno-electron microscopy images to show that the LngB protein could be localized at the tip of CS21. In conclusion, our results demonstrate that the LngA, LngB, LngC, LngD, LngH, and LngP proteins are essential for CS21 assembly, as well as for bacterial aggregation and adherence to HT-29 cells.
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico GómezCiudad de México, Mexico; Instituto de Fisiología Celular at the Universidad Nacional Autónoma de MéxicoCiudad de México, Mexico.
authors.forename: Zeus
authors.initials: Z
authors.lastname: Saldaña-Ahuactzi
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico GómezCiudad de México, Mexico; Instituto de Fisiología Celular at the Universidad Nacional Autónoma de MéxicoCiudad de México, Mexico.
authors.forename: Gerardo E
authors.initials: GE
authors.lastname: Rodea
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Ariadnna
authors.initials: A
authors.lastname: Cruz-Córdova
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Viridiana
authors.initials: V
authors.lastname: Rodríguez-Ramírez
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Karina
authors.initials: K
authors.lastname: Espinosa-Mazariego
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Martín A
authors.initials: MA
authors.lastname: González-Montalvo
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Sara A
authors.initials: SA
authors.lastname: Ochoa
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico.
authors.forename: Bertha
authors.initials: B
authors.lastname: González-Pedrajo
authors.affiliation: Departamento de Salud Pública, Facultad de Medicina, Universidad Nacional Autónoma de México Ciudad de México, Mexico.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Eslava-Campos
authors.affiliation: Laboratorio Central de Microscopía, Departamento de Investigación-SEPI, Instituto Politecnico Nacional Ciudad de México, Mexico.
authors.forename: Edgar O
authors.initials: EO
authors.lastname: López-Villegas
authors.affiliation: Departamento de Ecología de Agentes Patógenos, Hospital General "Dr. Manuel Gea González" Ciudad de México, Mexico.
authors.forename: Rigoberto
authors.initials: R
authors.lastname: Hernández-Castro
authors.affiliation: Departamento de Infectología, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: José
authors.initials: J
authors.lastname: Arellano-Galindo
authors.affiliation: Laboratorio de Investigación en Inmunología y Proteómica, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Genaro
authors.initials: G
authors.lastname: Patiño-López
authors.affiliation: Laboratorio de Investigación en Bacteriología Intestinal, Hospital Infantil de México Federico Gómez Ciudad de México, Mexico.
authors.forename: Juan
authors.initials: J
authors.lastname: Xicohtencatl-Cortes
keywords: CS21; ETEC; adherence to intestinal cells; biogenesis; pilus; type IV pilus