HrpZ from the plant pathogen Pseudomonas syringae binds to lipid bilayers and forms a cation-conducting pore in vivo. This pore-forming activity may allow nutrient release or delivery of virulence factors during bacterial colonisation of host plants [1]. The family of hairpinN proteins, Harpin, has been merged into this family. HrpN is a virulence determinant which elicits lesion formation in Arabidopsis and tobacco and triggers systemic resistance in Arabidopsis [2].

1: HrpZ(Psph) from the plant pathogen Pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. Lee J, Klusener B, Tsiamis G, Stevens C, Neyt C, Tampakaki AP, Panopoulos NJ, Noller J, Weiler EW, Cornelis GR, Mansfield JW, Nurnberger T; Proc Natl Acad Sci U S A 2001;98:289-294. PMID:11134504

2: Erwinia carotovora subsp. carotovora and Erwinia-derived elicitors HrpN and PehA trigger distinct but interacting defense responses and cell death in Arabidopsis. Kariola T, Palomaki TA, Brader G, Palva ET; Mol Plant Microbe Interact 2003;16:179-187. PMID:12650449