Similar structural basis for membrane localization and protein priming by an RNA-dependent RNA polymerase.
Protein primers are used to initiate genomic synthesis of several RNA and DNA viruses, although the structural details of the primer-polymerase interactions are not yet known. Poliovirus polymerase binds with high affinity to the membrane-bound viral protein 3AB but uridylylates only the smaller peptide 3B in vitro. Mutational analysis of the polymerase identified four surface residues on the three-dimensional structure of poliovirus polymerase whose wild-type identity is required for 3AB binding. These mutants also decreased 3B uridylylation, arguing that the binding sites for the membrane tether and the protein primer overlap. Mutation of flanking residues between the 3AB binding site and the polymerase active site specifically decreased 3B uridylylation, likely affecting steps subsequent to binding. The physical overlap of sites for protein priming and membrane association should facilitate replication initiation in the membrane-associated complex.
Lyle
John M
JM
Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305, USA.
Clewell
Amy
A
Richmond
Kathryn
K
Richards
Oliver C
OC
Hope
Debra A
DA
Schultz
Steve C
SC
Kirkegaard
Karla
K
D001483:Base Sequence; D001665:Binding Sites; D002462:Cell Membrane / Q000201:enzymology*; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D017955:Poliovirus / Q000201:enzymology; D011487:Protein Conformation; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics
D017931:DNA Primers; D011994:Recombinant Proteins; D012324:RNA-Dependent RNA Polymerase