Mutations in the zinc-binding motif of the reovirus capsid protein delta 3 eliminate its ability to associate with capsid protein mu 1.
Reovirus capsid protein delta 3 binds both double-stranded RNA (dsRNA) and zinc. Previous studies have revealed that the amino-terminal zinc finger is not required for the ability of delta 3 to bind dsRNA. We expressed wild-type and mutant delta 3 molecules by in vitro transcription/translation to evaluate the importance of the zinc finger for other functions of delta 3. delta 3 molecules with mutations in the zinc finger did not form complexes with capsid protein mu 1 but bound dsRNA more efficiently than wild-type delta 3 did. In contrast, a dsRNA-binding mutant was unimpaired in its ability to associate with mu 1. Studies with delta 3 fragments support these findings and indicate that sequences critical for delta 3's interaction with mu 1 lie in the amino terminus of the molecule. Our finding that mu 1 and dsRNA do not compete for identical binding sites on delta 3 has implications for its function as a translational regulator in infected cells.
Shepard
D A
DA
Department of Microbiology, University of Minnesota, Minneapolis 55455, USA.
Ehnstrom
J G
JG
Skinner
P J
PJ
Schiff
L A
LA
D001665:Binding Sites; D002213:Capsid / Q000378:metabolism*; D036022:Capsid Proteins; D002460:Cell Line; D016297:Mutagenesis, Site-Directed; D016601:RNA-Binding Proteins; D012087:Reoviridae / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D016335:Zinc Fingers / Q000502:physiology
D036022:Capsid Proteins; D016601:RNA-Binding Proteins; D014764:Viral Proteins; C055356:mu1 protein, Reovirus; C053179:sigma protein 3, Reovirus