Structural highlights
Function
POLN_MAYAB P123 and P123' are short-lived polyproteins, accumulating during early stage of infection. P123 is directly translated from the genome, whereas P123' is a product of the cleavage of P1234. They localize the viral replication complex to the cytoplasmic surface of modified endosomes and lysosomes. By interacting with nsP4, they start viral genome replication into antigenome. After these early events, P123 and P123' are cleaved sequentially into nsP1, nsP2 and nsP3/nsP3'. This sequence of delayed processing would allow correct assembly and membrane association of the RNA polymerase complex (By similarity). nsP1 is a cytoplasmic capping enzyme. This function is necessary since all viral RNAs are synthesized in the cytoplasm, and host capping enzymes are restricted to the nucleus. The enzymatic reaction involves a covalent link between 7-methyl-GMP and nsP1, whereas eukaryotic capping enzymes form a covalent complex only with GMP. nsP1 capping would consist in the following reactions: GTP is first methylated and then forms the m7GMp-nsP1 complex, from which 7-methyl-GMP complex is transferred to the mRNA to create the cap structure. Palmitoylated nsP1 is remodeling host cell cytoskeleton, and induces filopodium-like structure formation at the surface of the host cell (By similarity). nsP2 has two separate domain with different biological activities. The N-terminal section is part of the RNA polymerase complex and has RNA trisphosphatase and RNA helicase activity. The C-terminal section harbors a protease that specifically cleaves and releases the four mature proteins. Also inhibits cellular transcription by inducing rapid degradation of POLR2A, a catalytic subunit of the RNAPII complex. The resulting inhibition of cellular protein synthesis serves to ensure maximal viral gene expression and to evade host immune response (By similarity). nsP3 and nsP3' are essential for minus strand and subgenomic 26S mRNA synthesis. nsP4 is an RNA dependent RNA polymerase. It replicates genomic and antigenomic RNA by recognizing replications specific signals. Transcribes also a 26S subgenomic mRNA by initiating RNA synthesis internally on antigenomic RNA. This 26S mRNA codes for structural proteins. nsP4 is a short-lived protein regulated by several ways: the opal codon readthrough and degradation by ubiquitin pathway (By similarity).
Publication Abstract from PubMed
Mayaro virus (MAYV) is a member of Togaviridae family which also includes Chikungunya virus as a notorious member. MAYV recently emerged in urban areas of the Americas, and this emergence emphasized the current paucity of knowledge about its replication cycle. The macro domain (MD) of MAYV belongs to the N-terminal region of its non-structural protein 3, part of the replication complex. Here, we report the first structural and dynamical characterization of a previously unexplored Alphavirus macro domain investigated through high resolution NMR spectroscopy, along with data on its ligand selectivity and binding properties. The structural analysis of MAYV MD reveals a typical "macro" (betabetaalphabetabetaalphabetaalphabetaalpha) fold for this polypeptide, while NMR-driven interaction studies provide in-depth insights into MAYV MD - ligand adducts. NMR data in concert with thermodynamics and biochemical studies provide convincing experimental evidence for preferential binding of adenosine diphosphate ribose (ADP-r) and adenine-rich RNAs to MAYV MD, thus shedding light on the structure-function relationship of a previously unexplored viral MD. The emerging differences with any other related macro domain are expected to enlighten distinct functions.
Deciphering the Nucleotide and RNA Binding Selectivity of the Mayaro Virus Macro Domain.,Tsika AC, Melekis E, Tsatsouli SA, Papageorgiou N, Mate MJ, Canard B, Coutard B, Bentrop D, Spyroulias GA J Mol Biol. 2019 Apr 15. pii: S0022-2836(19)30207-4. doi:, 10.1016/j.jmb.2019.04.013. PMID:30998933[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Tsika AC, Melekis E, Tsatsouli SA, Papageorgiou N, Mate MJ, Canard B, Coutard B, Bentrop D, Spyroulias GA. Deciphering the Nucleotide and RNA Binding Selectivity of the Mayaro Virus Macro Domain. J Mol Biol. 2019 Apr 15. pii: S0022-2836(19)30207-4. doi:, 10.1016/j.jmb.2019.04.013. PMID:30998933 doi:http://dx.doi.org/10.1016/j.jmb.2019.04.013
