Open AccessA PERK-Like Receptor Kinase Interacts with the Geminivirus Nuclear Shuttle Protein and Potentiates Viral Infection
Author(s) -
Lílian H. Florentino,
Anésia A. Santos,
M. R. Fontenelle,
Guilherme L. Pinheiro,
F. Murilo Zerbini,
Maria Cristina BaracatPereira,
Elizabeth P. B. Fontes
Publication year - 2006
Publication title -
journal of virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.617
H-Index - 292
eISSN - 1070-6321
pISSN - 0022-538X
DOI - 10.1128/jvi.00173-06
Subject(s) - biology , protein kinase domain , transmembrane protein , protein kinase a , kinase , microbiology and biotechnology , map2k7 , mitogen activated protein kinase kinase , biochemistry , cyclin dependent kinase 2 , receptor , gene , mutant
The nuclear shuttle protein (NSP) from bipartite geminiviruses facilitates the intracellular transport of viral DNA from the nucleus to the cytoplasm and acts in concert with the movement protein (MP) to promote the cell-to-cell spread of the viral DNA. A proline-rich extensin-like receptor protein kinase (PERK) was found to interact specifically with NSP ofCabbage leaf curl virus (CaLCuV) and of tomato-infecting geminiviruses through a yeast two-hybrid screening. The PERK-like protein, which we designated NsAK (for NSP-associated kinase), is structurally organized into a proline-rich N-terminal domain, followed by a transmembrane segment and a C-terminal serine/threonine kinase domain. The viral protein interacted stably with defective versions of the NsAK kinase domain, but not with the potentially active enzyme, in an in vitro binding assay. In vitro-translated NsAK enhanced the phosphorylation level of NSP, indicating that NSP functions as a substrate for NsAK. These results demonstrate that NsAK is an authentic serine/threonine kinase and suggest a functional link for NSP-NsAK complex formation. This interpretation was corroborated by in vivo infectivity assays showing that loss of NsAK function reduces the efficiency of CaLCuV infection and attenuates symptom development. Our data implicate NsAK as a positive contributor to geminivirus infection and suggest it may regulate NSP function.