Effect of the O-Antigen Length of Lipopolysaccharide on the Functions of Type III Secretion Systems in Salmonella enterica

Autor(en): Hoelzer, Stefanie U.
Schlumberger, Markus C.
Jaeckel, Daniela
Hensel, Michael 
Stichwörter: BACTERIAL-RESISTANCE; CHAIN-LENGTH; ESCHERICHIA-COLI; HOST-CELLS; Immunology; Infectious Diseases; LIPID-A-CORE; PATHOGENICITY ISLAND-2; PSEUDOMONAS-AERUGINOSA; SEROVAR TYPHIMURIUM; SERUM RESISTANCE; SHIGELLA-FLEXNERI 2A
Erscheinungsdatum: 2009
Herausgeber: AMER SOC MICROBIOLOGY
Journal: INFECTION AND IMMUNITY
Volumen: 77
Ausgabe: 12
Startseite: 5458
Seitenende: 5470
Zusammenfassung: 
The virulence of Salmonella enterica critically depends on the functions of two type III secretion systems (T3SS), with the Salmonella pathogenicity island 1 (SPI1)-encoded T3SS required for host cell invasion and the SPI2-T3SS enabling Salmonella to proliferate within host cells. A further T3SS is required for the assembly of the flagella. Most serovars of Salmonella also possess a lipopolysaccharide with a complex O-antigen (OAg) structure. The number of OAg units attached to the core polysaccharide varies between 16 and more than 100 repeats, with a trimodal distribution. This work investigated the correlation of the OAg length with the functions of the SPI1-T3SS and the SPI2-T3SS. We observed that the number of repeats of OAg units had no effect on bacterial motility. The interaction of Salmonella with epithelial cells was altered if the OAg structure was changed by mutations in regulators of OAg. Strains defective in synthesis of very long or long and very long OAg species showed increased translocation of a SPI1-T3SS effector protein and increased invasion. Invasion of a strain entirely lacking OAg was increased, but this mutant strain also showed increased adhesion. In contrast, translocation of a SPI2-T3SS effector protein and intracellular replication were not affected by modification of the OAg length. Mutant strains lacking the entire OAg or long and very long OAg were highly susceptible to complement killing. These observations indicate that the architecture of the outer membrane of Salmonella is balanced to permit sufficient T3SS function but also to confer optimal protection against antimicrobial defense mechanisms.
ISSN: 00199567
DOI: 10.1128/IAI.00871-09

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