Shared and group-specific features of the rotavirus RNA polymerase reveal potential determinants of gene reassortment restriction.
Rotaviruses (RVs) are nonenveloped, 11-segmented, double-stranded RNA viruses that are major pathogens associated with acute gastroenteritis. Group A, B, and C RVs have been isolated from humans; however, intergroup gene reassortment does not occur for reasons that remain unclear. This restriction might reflect the failure of the viral RNA-dependent RNA polymerase (RdRp; VP1) to recognize and replicate the RNA of a different group. To address this possibility, we contrasted the sequences, structures, and functions of RdRps belonging to RV groups A, B, and C (A-VP1, B-VP1, and C-VP1, respectively). We found that conserved amino acid residues are located within the hollow center of VP1 near the active site, whereas variable, group-specific residues are mostly surface exposed. By creating a three-dimensional homology model of C-VP1 with the A-VP1 crystallographic data, we provide evidence that these RV RdRps are nearly identical in their tertiary folds and that they have the same RNA template recognition mechanism that differs from that of B-VP1. Consistent with the structural data, recombinant A-VP1 and C-VP1 are capable of replicating one another's RNA templates in vitro. Nonetheless, the activity of both RdRps is strictly dependent upon the presence of cognate RV core shell protein A-VP2 or C-VP2, respectively. Together, the results of this study provide unprecedented insight into the structure and function of RV RdRps and support the notion that VP1 interactions may influence the emergence of reassortant viral strains.
Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20826-8026, USA.
Sarah M
SM
McDonald
Daniel
D
Aguayo
Fernando D
FD
Gonzalez-Nilo
John T
JT
Patton
D000595:Amino Acid Sequence; D020134:Catalytic Domain; D017124:Conserved Sequence; D015321:Gene Rearrangement; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D012401:Rotavirus / Q000235:genetics*; D016415:Sequence Alignment; D014758:Viral Core Proteins / Q000235:genetics*
D012367:RNA, Viral; C069187:VP1 protein, Rotavirus; D014758:Viral Core Proteins; D012324:RNA-Dependent RNA Polymerase