title: TGBp3 triggers the unfolded protein response and SKP1-dependent programmed cell death.
abstract: The Potato virus X (PVX) triple gene block protein 3 (TGBp3), an 8-kDa membrane binding protein, aids virus movement and induces the unfolded protein response (UPR) during PVX infection. TGBp3 was expressed from the Tobacco mosaic virus (TMV) genome (TMV-p3), and we noted the up-regulation of SKP1 and several endoplasmic reticulum (ER)-resident chaperones, including the ER luminal binding protein (BiP), protein disulphide isomerase (PDI), calreticulin (CRT) and calmodulin (CAM). Local lesions were seen on leaves inoculated with TMV-p3, but not TMV or PVX. Such lesions were the result of TGBp3-elicited programmed cell death (PCD), as shown by an increase in reactive oxygen species, DNA fragmentation and induction of SKP1 expression. UPR-related gene expression occurred within 8 h of TMV-p3 inoculation and declined before the onset of PCD. TGBp3-mediated cell death was suppressed in plants that overexpressed BiP, indicating that UPR induction by TGBp3 is a pro-survival mechanism. Anti-apoptotic genes Bcl-xl, CED-9 and Op-IAP were expressed in transgenic plants and suppressed N gene-mediated resistance to TMV, but failed to alleviate TGBp3-induced PCD. However, TGBp3-mediated cell death was reduced in SKP1-silenced Nicotiana benthamiana plants. The combined data suggest that TGBp3 triggers the UPR and elicits PCD in plants.
authors: Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA.
authors: Chang-Ming
authors: CM
authors: Ye
authors: Shaorong
authors: S
authors: Chen
authors: Mark
authors: M
authors: Payton
authors: Martin B
authors: MB
authors: Dickman
authors: Jeanmarie
authors: J
authors: Verchot
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D017863:Potexvirus / Q000235:genetics / Q000378:metabolism*; D014027:Tobacco Mosaic Virus / Q000235:genetics / Q000378:metabolism; D056811:Unfolded Protein Response / Q000235:genetics / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D014764:Viral Proteins