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X-ray structure and activities of an essential Mononegavirales L- protein domainX-ray structure and activities of an essential Mononegavirales L- protein domain
Structural highlights
Function[L_HMPVC] Displays RNA-directed RNA polymerase, mRNA guanylyl transferase, mRNA (guanine-N(7)-)-methyltransferase and poly(A) synthetase activities. The viral mRNA guanylyl transferase displays a different biochemical reaction than the cellular enzyme. The template is composed of the viral RNA tightly encapsidated by the nucleoprotein (N). Functions either as transcriptase or as replicase. The transcriptase synthesizes subsequently the subgenomic RNAs, assuring their capping and polyadenylation by a stuttering mechanism. The replicase mode is dependent on intracellular protein N concentration. In this mode, the polymerase replicates the whole viral genome without recognizing the transcriptional signals (By similarity). Publication Abstract from PubMedThe L protein of mononegaviruses harbours all catalytic activities for genome replication and transcription. It contains six conserved domains (CR-I to -VI; Fig. 1a). CR-III has been linked to polymerase and polyadenylation activity, CR-V to mRNA capping and CR-VI to cap methylation. However, how these activities are choreographed is poorly understood. Here we present the 2.2-A X-ray structure and activities of CR-VI+, a portion of human Metapneumovirus L consisting of CR-VI and the poorly conserved region at its C terminus, the +domain. The CR-VI domain has a methyltransferase fold, which besides the typical S-adenosylmethionine-binding site ((SAM)P) also contains a novel pocket ((NS)P) that can accommodate a nucleoside. CR-VI lacks an obvious cap-binding site, and the (SAM)P-adjoining site holding the nucleotides undergoing methylation ((SUB)P) is unusually narrow because of the overhanging +domain. CR-VI+ sequentially methylates caps at their 2'O and N7 positions, and also displays nucleotide triphosphatase activity. X-ray structure and activities of an essential Mononegavirales L-protein domain.,Paesen GC, Collet A, Sallamand C, Debart F, Vasseur JJ, Canard B, Decroly E, Grimes JM Nat Commun. 2015 Nov 9;6:8749. doi: 10.1038/ncomms9749. PMID:26549102[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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