2gu0
From Proteopedia
Crystal Structure of Human Rotavirus NSP2 (Group C / Bristol Strain)
Structural highlights
Function[NSP2_ROTHC] Involved in genome replication and packaging. Plays a crucial role, together with NSP5, in the formation of virus factories (viroplasms) which are large inclusions in the cytoplasm where replication intermediates are assembled and RNA replication takes place. Displays ssRNA binding, NTPase, RNA triphosphatase (RTPase) and ATP-independent helix-unwinding activity activities. The unwiding activity may prepare and organize plus-strand RNAs for packaging and replication by removing interfering secondary structures. Unlike typical helicases, NSP2 requires neither a divalent cation nor a nucleotide energy source for helix destabilization. The RTPase activity may account for the absence of the 5'-terminal gamma-phosphate on the minus-strands of dsRNA genome segments (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedViral 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. Structure-function analysis of rotavirus NSP2 octamer by using a novel complementation system.,Taraporewala ZF, Jiang X, Vasquez-Del Carpio R, Jayaram H, Prasad BV, Patton JT J Virol. 2006 Aug;80(16):7984-94. PMID:16873255[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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