tal effectors target the c-terminal domain of rna polymerase ii (ctd) by inhibiting the prolyl-isomerase activity of a ctd-associated cyclophilintal效应器目标c端域的rna聚合酶ii(ctd)通过抑制prolyl-isomerase还有ctd-associated的活动.pdf

TAL Effectors Target the C-Terminal Domain of RNA Polymerase II (CTD) by Inhibiting the Prolyl-Isomerase Activity of a CTD-Associated Cyclophilin . . Mariane Noronha Domingues , Bruna Medeia de Campos , Maria Luiza Peixoto de Oliveira, Uli Quirino de Mello, Celso Eduardo Benedetti* ´ ˆ Laboratorio Nacional de Biociencias, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, Brazil Abstract Transcriptional activator-like (TAL) effectors of plant pathogenic bacteria function as transcription factors in plant cells. However, how TAL effectors control transcription in the host is presently unknown. Previously, we showed that TAL effectors of the citrus canker pathogen Xanthomonas citri, named PthAs, targeted the citrus protein complex comprising the thioredoxin CsTdx, ubiquitin-conjugating enzymes CsUev/Ubc13 and cyclophilin CsCyp. Here we show that CsCyp complements the function of Cpr1 and Ess1, two yeast cyclophilins that regulate transcription by the isomerization of proline residues of the regulatory C-terminal domain (CTD) of RNA polymerase II. We also demonstrate that CsCyp, CsTdx, CsUev and four PthA variants interact with the citrus CTD and that CsCyp co-immunoprecipitate with the CTD in citrus cell extracts and with PthA2 transiently expressed in sweet orange epicotyls. The interactions of CsCyp with the CTD and PthA2 were inhibited by cyclosporin A (CsA), a cyclophilin inhibitor. Moreover, we present evidence that PthA2 inhibits the peptidyl-prolyl cis-trans isomerase (PPIase) activi