Zhang Bo, Tremousaygue Dominique, Denancé Nicolas, van Esse H Peter, Hörger Anja C, Dabos Patrick, Goffner Deborah, Thomma Bart P H J, van der Hoorn Renier A L, Tuominen Hannele
Umeå Plant Science Centre (UPSC), Department of Plant Physiology, Umeå University, 901 87, Umeå, Sweden.
Plant J. 2014 Sep;79(6):1009-19. doi: 10.1111/tpj.12602. Epub 2014 Aug 7.
PIRIN (PRN) is a member of the functionally diverse cupin protein superfamily. There are four members of the Arabidopsis thaliana PRN family, but the roles of these proteins are largely unknown. Here we describe a function of the Arabidopsis PIRIN2 (PRN2) that is related to susceptibility to the bacterial plant pathogen Ralstonia solanacearum. Two prn2 mutant alleles displayed decreased disease development and bacterial growth in response to R. solanacearum infection. We elucidated the underlying molecular mechanism by analyzing PRN2 interactions with the papain-like cysteine proteases (PLCPs) XCP2, RD21A, and RD21B, all of which bound to PRN2 in yeast two-hybrid assays and in Arabidopsis protoplast co-immunoprecipitation assays. We show that XCP2 is stabilized by PRN2 through inhibition of its autolysis on the basis of PLCP activity profiling assays and enzymatic assays with recombinant protein. The stabilization of XCP2 by PRN2 was also confirmed in planta. Like prn2 mutants, an xcp2 single knockout mutant and xcp2 prn2 double knockout mutant displayed decreased susceptibility to R. solanacearum, suggesting that stabilization of XCP2 by PRN2 underlies susceptibility to R. solanacearum in Arabidopsis.
吡啉蛋白（PIRIN，PRN）是功能多样的cupin蛋白超家族的成员之一。拟南芥PRN家族有四个成员，但这些蛋白的功能大多未知。在此，我们描述了拟南芥吡啉蛋白2（PRN2）的一项功能，该功能与植物对细菌性病原菌青枯雷尔氏菌的易感性有关。两个prn2突变等位基因在受到青枯雷尔氏菌感染时，病害发展和细菌生长均有所减少。我们通过分析PRN2与木瓜蛋白酶样半胱氨酸蛋白酶（PLCP）XCP2、RD21A和RD21B的相互作用，阐明了其潜在的分子机制，在酵母双杂交试验和拟南芥原生质体共免疫沉淀试验中，这些蛋白酶均与PRN2结合。基于PLCP活性分析试验和重组蛋白酶活性试验，我们发现PRN2通过抑制XCP2的自溶作用使其稳定。PRN2对XCP2的稳定作用在植物体内也得到了证实。与prn2突变体一样，xcp2单基因敲除突变体和xcp2 prn2双基因敲除突变体对青枯雷尔氏菌的易感性均降低，这表明PRN2对XCP2的稳定作用是拟南芥对青枯雷尔氏菌易感性的基础。
