The gene coding for the Hrp pilus structural protein is required for type III secretion of Hrp and Avr proteins in Pseudomonas syringae pv. tomato.

Journal Article

Bacterial surface appendages called pili often are associated with DNA and/or protein transfer between cells. The exact function of pili in the transfer process is not understood and is a matter of considerable debate. The Hrp pilus is assembled by the Hrp type III protein secretion system of Pseudomonas syringae pv. tomato (Pst) strain DC3000. In this study, we show that the hrpA gene, which encodes the major subunit of the Hrp pilus, is required for secretion of putative virulence proteins, such as HrpW and AvrPto. In addition, the hrpA gene is required for full expression of genes that encode regulatory, secretion, and effector proteins of the type III secretion system. hrpA-mediated gene regulation apparently is through effect on the mRNA level of two previously characterized regulatory genes, hrpR and hrpS. Ectopic expression of the hrpRS gene operon restored gene expression, but not protein secretion, in the hrpA mutant. Three single amino acid mutations at the HrpA carboxyl terminus were identified that affect the secretion or regulatory function of the HrpA protein. These results define an essential role of the Hrp pilus structural gene in protein secretion and coordinate regulation of the type III secretion system in Pst DC3000.

Full Text

Duke Authors

Cited Authors

  • Wei, W; Plovanich-Jones, A; Deng, WL; Jin, QL; Collmer, A; Huang, HC; He, SY

Published Date

  • February 2000

Published In

Volume / Issue

  • 97 / 5

Start / End Page

  • 2247 - 2252

PubMed ID

  • 10681465

Pubmed Central ID

  • 10681465

Electronic International Standard Serial Number (EISSN)

  • 1091-6490

International Standard Serial Number (ISSN)

  • 0027-8424

Digital Object Identifier (DOI)

  • 10.1073/pnas.040570097

Language

  • eng