The myxoma virus m-t5 ankyrin repeat host range protein is a novel adaptor that coordinately links the cellular signaling pathways mediated by Akt and Skp1 in virus-infected cells.
Most poxviruses express multiple proteins containing ankyrin (ANK) repeats accounting for a large superfamily of related but unique determinants of poxviral tropism. Recently, select members of this novel family of poxvirus proteins have drawn considerable attention for their potential roles in modulating intracellular signaling networks during viral infection. The rabbit-specific poxvirus, myxoma virus (MYXV), encodes four unique ANK repeat proteins, termed M-T5, M148, M149, and M150, all of which include a carboxy-terminal PRANC domain which closely resembles a cellular protein motif called the F-box domain. Here, we show that each MYXV-encoded ANK repeat protein, including M-T5, interacts directly with the Skp1 component of the host SCF ubiquitin ligase complex, and that the binding of M-T5 to cullin 1 is indirect via binding to Skp1 in the host SCF complex. To understand the significance of these virus-host protein interactions, the various binding domains of M-T5 were mapped. The N-terminal ANK repeats I and II were identified as being important for interaction with Akt, whereas the C-terminal PRANC/F-box-like domain was essential for binding to Skp1. We also report that M-T5 can bind Akt and the host SCF complex (via Skp1) simultaneously in MYXV-infected cells. Finally, we report that M-T5 specifically mediates the relocalization of Akt from the nucleus to the cytoplasm during infection with the wild-type MYXV, but not the M-T5 knockout version of the virus. These results indicate that ANK/PRANC proteins play a critical role in reprogramming disparate cellular signaling cascades to establish a new cellular environment more favorable for virus replication.
Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
Steven J
SJ
Werden
Jerry
J
Lanchbury
Donna
D
Shattuck
Chris
C
Neff
Max
M
Dufford
Grant
G
McFadden
D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D002522:Chlorocebus aethiops; D044842:Cullin Proteins / Q000378:metabolism; D003593:Cytoplasm / Q000737:chemistry; D006801:Humans; D009233:Myxoma virus / Q000472:pathogenicity*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D044786:S-Phase Kinase-Associated Proteins / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism; D015398:Signal Transduction; D014764:Viral Proteins / Q000502:physiology*
C100318:Cullin 1; D044842:Cullin Proteins; C100338:M-T5 protein, Myxoma virus; D044786:S-Phase Kinase-Associated Proteins; D014764:Viral Proteins; D044843:SKP Cullin F-Box Protein Ligases; D051057:Proto-Oncogene Proteins c-akt