2hwt
NMR solution structure of the Master-Rep protein nuclease domain (2-95) from the Faba Bean Necrotic Yellows Virus
Structural highlights
FunctionMREP_FBNY2 Essential for the replication of all genomic viral ssDNA (trans-replication). The closed circular ssDNA genome is first converted to a superhelical dsDNA. Rep binds a specific hairpin at the genome origin of replication. Introduces an endonucleolytic nick within the conserved sequence 5'-A[GT]TATTAC-3' in the intergenic region of the genome, thereby initiating the rolling circle replication (RCR). Following cleavage, binds covalently to the 5'-phosphate of DNA as a tyrosyl ester. The cleavage gives rise to a free 3'-OH that serves as a primer for the cellular DNA polymerase. The polymerase synthesizes the (+) strand DNA by rolling circle mechanism. After one round of replication, a Rep-catalyzed nucleotidyl transfer reaction releases a circular single-stranded virus genome, thereby terminating the replication. Displays origin-specific DNA cleavage, nucleotidyl transferase, ATPase and helicase activities. 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 PubMedNanoviruses are a family of plant viruses that possess a genome of multiple circular single-stranded DNA (ssDNA) components and are strikingly similar in their replication mode to the plant geminiviruses and to the circoviruses that infect birds or mammals. These viruses multiply by rolling circle replication using virus-encoded multifunctional replication initiator proteins (Rep proteins) that catalyze the initiation of replication on a double-stranded DNA (dsDNA) intermediate and the resolution of the ssDNA into circles. Here we report the solution NMR three-dimensional structure of the endonuclease domain from the master Rep (M-Rep) protein of faba bean necrotic yellows virus (FBNYV), a representative of the nanoviruses. The domain comprises amino acids 2-95 (M-Rep2-95), and its global fold is similar to those previously described for the gemini- and circovirus Rep endonuclease domains, consisting of a central 5-stranded antiparallel beta-sheet covered on one side by an alpha-helix and irregular loops and on the other, more open side of the domain, by an alpha-helix containing the catalytic tyrosine residue (the catalytic helix). Longer domain constructs extending to amino acids 117 and 124 were also characterized. They contain an additional alpha-helix, are monomeric, and exhibit catalytic activity indistinguishable from that of M-Rep2-95. The binding site for the catalytic metal was identified by paramagnetic broadening and maps to residues on the exposed face of the central beta-sheet. A comparison with the previously determined Rep endonuclease domain structures of tomato yellow leaf curl Sardinia virus (TYLCSV), a geminivirus, and that of porcine circovirus type 2 (PCV2) Rep allows the identification of a positively charged surface that is most likely involved in dsDNA binding, and reveals common features shared by all endonuclease domains of nanovirus, geminivirus, and circovirus Rep proteins. Solution structure of the endonuclease domain from the master replication initiator protein of the nanovirus faba bean necrotic yellows virus and comparison with the corresponding geminivirus and circovirus structures.,Vega-Rocha S, Gronenborn B, Gronenborn AM, Campos-Olivas R Biochemistry. 2007 May 29;46(21):6201-12. Epub 2007 May 2. PMID:17472345[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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