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Publication Abstract from PubMed

Rotavirus non-structural protein NSP2, a functional octamer, is critical for the formation of viroplasms, which are exclusive sites for replication and packaging of segmented double-stranded RNA (dsRNA) rotavirus genome. As a component of replication intermediates, NSP2 is also implicated in various replication-related activities. In addition to sequence-independent single-stranded RNA binding and helix-destabilizing activities, NSP2 exhibits monomer-associated nucleoside and 5' RNA triphosphatase (NTPase/RTPase) activities which are mediated by a conserved H225 residue within a narrow enzymatic cleft. Lack of a 5' gamma-phosphate is a common feature of the (-)RNA of the packaged dsRNA segments in RV. Strikingly, all (-)RNAs (in group A RV) have a 5' GG dinucleotide sequence. As the only rotavirus protein with 5' RTPase activity, NSP2 is implicated in the removal of the gamma-phosphate from the rotavirus minus-strand RNA. To understand how NSP2, despite its sequence-independent RNA binding property, recognizes minus-strand RNA to hydrolyze the gamma-phosphate within the catalytic cleft, we determined a crystal structure of NSP2 in complex with the 5' consensus sequence of minus-strand rotavirus RNA. Our studies show that the 5' GG of the bound oligoribonucleotide interacts extensively with highly conserved residues in the NSP2 enzymatic cleft. While these residues provide GG-specific interactions, surface plasmon resonance studies suggest that the C-terminal helix and other basic residues outside the enzymatic cleft account for sequence-independent RNA binding of NSP2. A novel observation from our studies, which may have implications in viroplasm formation, is that the C-terminal helix of NSP2 exhibits two distinct conformations and engages in domain swapping interactions, which result in the formation of NSP2 octamer chains.

Crystallographic Analysis of Rotavirus NSP2-RNA Complex Reveals Specific Recognition of 5' -GG Sequence for RTPase activity.,Hu L, Chow DC, Patton JT, Palzkill T, Estes MK, Prasad BV J Virol. 2012 Jul 18. PMID:22811529^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.