Search

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 MD 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” (ββαββαβαβα) 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 MD are expected to enlighten distinct functions., Graphical abstract Unlabelled Image, Highlights • First conformational and dynamics study of a previously unexplored Alphavirus macro domain (Mayaro virus macro domain, or MAYV MD) • MAYV MD selectivity and binding of ADP-ribose revealed by NMR spectroscopy and ITC • Identification of critical residues for the ADP-ribose binding • MAYV MD preference for binding of RNAs rich in adenine observed by NMR spectroscopy • Binding studies provide new insights for the design of novel ligands for MAYV and other Alphaviruses MDs.

Graphical abstract, Highlights • ADPr’s binding triggers conformational changes to the whole VEEV macro domain. • High flexibility of the loops β5-α3 and α3-β6 assist the ADPr’s binding. • Loops around ADPr site undergo a transition pathway between apo and complex state., Venezuelan equine encephalitis virus (VEEV) is a new world alphavirus which can be involved in several central nervous system disorders such as encephalitis and meningitis. The VEEV genome codes for 4 non-structural proteins (nsP), of which nsP3 contains a Macro domain. Macro domains (MD) can be found as stand-alone proteins or embedded within larger proteins in viruses, bacteria and eukaryotes. Their most common feature is the binding of ADP-ribose (ADPr), while several macro domains act as ribosylation writers, erasers or readers. Alphavirus MD erase ribosylation but their precise contribution in viral replication is still under investigation. NMR-driven titration experiments of ADPr in solution with the VEEV macro domain (in apo- and complex state) show that it adopts a suitable conformation for ADPr binding. Specific experiments indicate that the flexibility of the loops β5-α3 and α3-β6 is critical for formation of the complex and assists a wrapping mechanism for ADPr binding. Furthermore, along with this sequence of events, the VEEV MD undergoes a conformational exchange process between the apo state and a low-populated “dark” conformational state.

Macro domains consist of 130-190 amino acid residues and appear to be highly conserved in all kingdoms of life. Intense research on this field has shown that macro domains bind ADP-ribose and other similar molecules, but their exact function still remains intangible. Macro domains are highly conserved in the Alphavirus genus and the Venezuelan equine encephalitis virus (VEEV) is a member of this genus that causes fatal encephalitis to equines and humans. In this study we report the high yield recombinant expression and preliminary solution NMR study of the macro domain of VEEV. An almost complete sequence-specific assignment of its (1)H, (15)N and (13)C resonances was obtained and its secondary structure predicted by TALOS+. The protein shows a unique mixed α/β-fold.

Macro domains are ADP-ribose-binding modules present in all eukaryotic organisms, bacteria and archaea. They are also found in non-structural proteins of several positive strand RNA viruses such as alphaviruses. Here, we report the high yield expression and preliminary structural analysis through solution NMR spectroscopy of the macro domain from New World Mayaro Alphavirus. The recombinant protein was well-folded and in a monomeric state. An almost complete sequence-specific assignment of its (1)H, (15)N and (13)C resonances was obtained and its secondary structure determined by TALOS+.

Four new manganese(III) porphyrins, heterogenised as insoluble zinc phosphonates, exhibit behaviour markedly different from their homogeneous counterparts in the competitive hydroxylation of alkane mixtures (i.e., cyclododecane–cyclohexane), using iodosylbenzene as the oxidant. The cyclohexanol:cyclododecanol ratio can be increased by as much as five, owing to shape selectivity effects imposed by the phosphonate support. Se′lectivite′ de forme pour l'hydroxylation d'alcanes, catalyse′e par des porphyrines de manganese he′te′roge′ne′ise′es sous forme de phosphonates de zinc. Une se′rie de quatre te′traarylporphyrines de manganese(III) he′te′roge′ne′ise′es sous forme de phosphonates de zinc insolubles, teste′es pour l'hyroxylation compe′titive de me′langes d'alcanes (par exemple, cyclodode′cane–cyclohexane) par l'iodosobenzene, montrent un comportement tres diffe′rent de celui de leurs homologues non supporte′s en milieu homogene. Le rapport cyclohexanol:cyclodode′canol peut augmenter d'un facteur allant jusqu'a cinq, sous l'effet d'une se′lectivite′ de forme induite par le support phosphonate.