期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：46
页码：16304-16309
DOI：10.1073/pnas.0406691101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Rotavirus NSP5 is a nonstructural protein that localizes in viroplasms of virus-infected cells. NSP5 interacts with NSP2 and undergoes a complex posttranslational hyperphosphorylation, generating species with reduced PAGE mobility. Here we show that NSP5 operates as an autoregulator of its own phosphorylation as a consequence of two distinct activities of the protein: substrate and activator. We developed an in vivo hyperphosphorylation assay in which two NSP5 mutant constructs are cotransfected. One of them, fused to an 11-aa tag, served as substrate whereas the other was used to map NSP5 domains required for activation. The activation and substrate activity could be uncoupled, demonstrating a hyperphosphorylation process in trans between the activator and substratum. This process involved dimerization of the two components through the 18-aa C-terminal tail. Phosphorylation of Ser-67 within the SDSAS motif (amino acids 63-67) was required to trigger hyperphosphorylation by promoting the activation function. We present evidence of casein kinase 1{alpha} being the protein kinase responsible for this key step as well as for the consecutive ones leading to NSP5 hyperphosphorylation.
