Type III secretion system outer membrane pore YscC/HrcC (IPR003522)

Short name: T3SS_OM_pore_YscC

Overlapping homologous superfamilies


Family relationships


Secretion of virulence factors in Gram-negative bacteria involves transportation of the protein across two membranes to reach the cell exterior. There have been four secretion systems described in animal enteropathogens such as Salmonella and Yersinia, with further sequence similarities in plant pathogens like Ralstonia and Erwinia [PMID: 8969244].

The type III secretion system is of great interest, as it is used to transport virulence factors from the pathogen directly into the host cell [PMID: 10334981] and is only triggered when the bacterium comes into close contact with the host. The protein subunits of the system are very similar to those of bacterial flagellar biosynthesis [PMID: 10564516]. However, while the latter forms a ring structure to allow secretion of flagellin and is an integral part of the flagellum itself [PMID: 10564516], type III subunits in the outer membrane translocate secreted proteins through a channel-like structure.

This family aids in the structural assembly of the invasion complex [PMID: 8733226]. Another characteristic of this family is its ability to form a channel through the outer bacterial membrane, allowing secretion to take place. Members include the Salmonella InvG and SpiA gene, the Shigella MxiD, and the Yersinia Kim5 and YscC proteins. Plant pathogen members include the Hypersensitivity Response (HR) genes of Burkholderia and Erwinia.

GO terms

Biological Process

GO:0009306 protein secretion

Molecular Function

No terms assigned in this category.

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.