The hantavirus nucleocapsid protein recognizes specific features of the viral RNA panhandle and is altered in conformation upon RNA binding.
Hantaviruses are tripartite negative-sense RNA viruses and members of the Bunyaviridae family. The nucleocapsid (N) protein is the principal structural component of the viral capsid. N forms a stable trimer that specifically recognizes the panhandle structure formed by the viral RNA termini. We used trimeric glutathione S-transferase (GST)-N protein and small RNA panhandles to examine the requirements for specific recognition by Sin Nombre hantavirus N. Trimeric GST-N recognizes the panhandles of the three viral RNAs (S, M, and L) with high affinity, whereas the corresponding plus-strand panhandles of the complementary RNA are recognized with lower affinity. Based on analysis of nucleotide substitutions that alter either the higher-order structure of the panhandle or the primary sequence of the panhandle, both secondary structure and primary sequence are necessary for stable interaction with N. A panhandle 23 nucleotides long is necessary and sufficient for high-affinity binding by N, and stoichiometry calculations indicate that a single N trimer interacts with a single panhandle. Surprisingly, displacement of the panhandle structure away from the terminus does not eliminate recognition by N. The binding of N to the panhandle is an entropy-driven process resulting in initial stable N-RNA interaction followed by a conformational change in N. Taken together, these data provide insight into the molecular events that take place during interaction of N with the panhandle and suggest that specific high-affinity interaction between an RNA binding domain of trimeric N and the panhandle is required for encapsidation of the three viral RNAs.
Mir
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MA
Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.
Panganiban
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D001483:Base Sequence; D015967:Gene Expression Regulation, Viral; D006476:Orthohantavirus / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D019590:Nucleocapsid Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013816:Thermodynamics; D019065:Virus Assembly
D019590:Nucleocapsid Proteins; D012367:RNA, Viral