The Structure of the Human Respiratory Syncytial Virus M2-1 Protein Bound to the Interaction Domain of the Phosphoprotein P Defines the Orientation of the Complex

Abstract

Human respiratory syncytial virus (HRSV) is a leading cause of respiratory illness, particularly in the young, elderly, and immunocompromised, and has also been linked to the development of asthma. HRSV replication depends on P and L, whereas transcription also requires M2-1. M2-1 interacts with P and RNA at overlapping binding sites; while these interactions are necessary for transcriptional activity, the mechanism of M2-1 action is unclear. To better understand HRSV transcription, we solved the crystal structure of M2-1 in complex with the minimal P interaction domain, revealing molecular details of the M2-1/P interface and defining the orientation of M2-1 within the tripartite complex. The M2-1/P interaction is relatively weak, suggesting high-affinity RNAs may displace M2-1 from the complex, providing the basis for a new model describing the role of M2-1 in transcription. Recently, the small molecules quercetin and cyclopamine have been used to validate M2-1 as a drug target.

Rational modifications, synthesis and biological evaluation of new potential antivirals for RSV designed to target the M2-1 protein

“…To an ethanolic solution of potassium hydroxide (1mmol/100mL) a secondary amine (1 mmol 20 The protein was pre-processed using the…”

“…The recently reported M2-1 protein complex crystal structure (PDB ID: 6G0Y) was used, and docking studies were performed using Glide SP scoring function. 20,35 Compound 1 is predicted to lie in a large pocket formed by three monomers immediately above the zinc-binding domain (ZBD) of one of them ( Figure 3A).…”

“…In this context, one appealing approach to inhibit zinc-binding enzymes is represented by metal chelation with zinc-ejecting compounds, as is the case for example of zinc-ejecting HIV nucleocapsid inhibitors, some of which have reached phase II clinical trials for the treatment of AIDS. 17 Starting from the identification of zinc-chelating small-molecule aldrithiol, AT-2, as inactivator of RSV at millimolar concentrations, 18 and thanks to the availability of crystal structures of RSV M2-1 protein complexes, [19][20] we have previously applied a structure-based drug design approach to this protein, which guided the synthesis of different new structural scaffolds. 21 These novel small-molecules were characterised by the presence of a central zincejecting chemical group, functionalised with different lateral substituents to interact with the protein sub-sites surrounding the ZBD.…”

Immune-Modulation by the Human Respiratory Syncytial Virus: Focus on Dendritic Cells

“…For its adequate function, the L protein requires the viral phosphoprotein P, which associates to this RNA polymerase (26, 27). Importantly, the replication of the viral genome and the transcription of its genes are modulated by the hRSV-encoded factors M2-1 and M2-2, which are generated from a common mRNA transcript by a ribosome shift that occurs on the mRNA after producing the M2-1 protein; initiation of M2-2 takes place at a start codon that overlaps with the M2-1 open reading frame (ORF) (23, 28). Noteworthy, in the virion and infected cells, the viral genome is covered by the nucleoprotein N, which is highly expressed within infected cells (29–31).…”

Structures of the Mononegavirales Polymerases

“…P acts as a chaperone to maintain a supply of RNA-free N (N 0 ) and delivers to N 0 nascent RNA genome or antigenome during replication(99,100,(115)(116)(117)(118)(119). (3) P interacts with other essential cofactors, such as M2-1 in Pneumoviridae, VP30 in Filoviridae, to coordinate the RNA synthesis activities of the RdRP(48,(120)(121)(122)(123).Overview of the structural analyses of the Mononegavirales polymerasesThe monomeric L and oligomeric P together constitute the RdRP in Mononegavirales. Due to the large size of L and the oligomeric states of P with intrinsically flexible domains, it is challenging to obtain the crystals of the Mononegavirales RdRPs (124).…”