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PMID:10861017

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Citation

Miao, EA and Miller, SI (2000) A conserved amino acid sequence directing intracellular type III secretion by Salmonella typhimurium. Proc. Natl. Acad. Sci. U.S.A. 97:7539-44

Abstract

Type III secretion systems (TTSS) are important virulence factors that Gram-negative bacteria use to translocate proteins into the cytoplasm of eukaryotic host cells. Salmonellae encode two virulence-associated TTSS. The Salmonella pathogenicity island 1 (SPI1)-encoded TTSS is active on contact with host cells, whereas the Salmonella pathogenicity island 2 (SPI2)-encoded TTSS is expressed after phagocytosis of bacteria by host cells. Previously, no consensus signal sequence for translocation has been identified among TTSS effector proteins. In this work, seven proteins, termed Salmonella-translocated effectors (STE), are described that contain conserved amino acid sequences that direct translocation by TTSS in Salmonella typhimurium. STE that are coordinately regulated with SPI2 gene expression contain translocation signals that are recognized by the SPI2 but not by the SPI1 TTSS. STE that are constitutively expressed contain signals that direct translocation through both SPI1 and SPI2 TTSS. Of the seven STE examined, SspH1 and SspH2 have been previously shown to be translocated and involved in virulence; SlrP and SifA were identified as virulence factors, but were not previously known to be associated with TTSS; and SseI, SseJ, and SifB were previously unidentified. Three STE genes (sspH1, sspH2, and sseI) are located within temperate bacteriophages, suggesting a common mechanism for the dissemination of more recently evolved STE.

Links

PubMed PMC16581

Keywords

Amino Acid Sequence; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Cell Line; Genes, Bacterial; Humans; Molecular Sequence Data; Open Reading Frames/genetics; Salmonella typhimurium/genetics; Salmonella typhimurium/metabolism; Salmonella typhimurium/pathogenicity; Sequence Alignment; Sequence Analysis, Protein; Virulence/genetics

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status

SALT1:SLRP

GO:0030254

protein secretion by the type III secretion system

IDA: Inferred from Direct Assay

P

Seeded From UniProt

complete

SALT1:SSPH1

GO:0030254

protein secretion by the type III secretion system

IDA: Inferred from Direct Assay

P

Seeded From UniProt

complete

SALT1:SSPH2

GO:0030254

protein secretion by the type III secretion system

IDA: Inferred from Direct Assay

P

complete

SALT1:SSPH2

GO:0020002

host cell plasma membrane

IDA: Inferred from Direct Assay

C

complete

SALT1:SSPH2

GO:0016567

protein ubiquitination

IDA: Inferred from Direct Assay

P

complete

SALT1:SSPH2

GO:0009405

pathogenesis

IDA: Inferred from Direct Assay

P

complete

SALT1:SSPH2

GO:0004842

ubiquitin-protein ligase activity

IDA: Inferred from Direct Assay

F

complete

SALT1:SSPH2

GO:0005623

cell

IDA: Inferred from Direct Assay

C

Seeded From UniProt

complete

SALT1:SSPH2

GO:0004842

ubiquitin-protein transferase activity

IDA: Inferred from Direct Assay

F

Seeded From UniProt

complete


See also

References

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