Structure-function analysis of rotavirus NSP2 octamer by using a novel complementation system.
Viral inclusion bodies, or viroplasms, that form in rotavirus-infected cells direct replication and packaging of the segmented double-stranded RNA (dsRNA) genome. NSP2, one of two rotavirus proteins needed for viroplasm assembly, possesses NTPase, RNA-binding, and helix-unwinding activities. NSP2 of the rotavirus group causing endemic infantile diarrhea (group A) was shown to self-assemble into large doughnut-shaped octamers with circumferential grooves and deep clefts containing nucleotide-binding histidine triad (HIT)-like motifs. Here, we demonstrate that NSP2 of group C rotavirus, a group that fails to reassort with group A viruses, retains the unique architecture of the group A octamer but differs in surface charge distribution. By using an NSP2-dependent complementation system, we show that the HIT-dependent NTPase activity of NSP2 is necessary for dsRNA synthesis, but not for viroplasm formation. The complementation system also showed that despite the retention of the octamer structure and the HIT-like fold, group C NSP2 failed to rescue replication and viroplasm formation in NSP2-deficient cells infected with group A rotavirus. The distinct differences in the surface charges on the Bristol and SA11 NSP2 octamers suggest that charge complementarity of the viroplasm-forming proteins guides the specificity of viroplasm formation and, possibly, reassortment restriction between rotavirus groups.
Taraporewala
Zenobia F
ZF
Laboratory of Infectious Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Jiang
Xiaofang
X
Vasquez-Del Carpio
Rodrigo
R
Jayaram
Hariharan
H
Prasad
B V Venkataram
BV
Patton
John T
JT
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D018360:Crystallography, X-Ray; D005816:Genetic Complementation Test / Q000379:methods*; D008969:Molecular Sequence Data; D043583:Nucleoside-Triphosphatase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D012330:RNA, Double-Stranded / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012401:Rotavirus / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics
D012330:RNA, Double-Stranded; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D017361:Viral Nonstructural Proteins; C079234:NS35 protein, rotavirus; D043583:Nucleoside-Triphosphatase