Functional and antigenic domains of the matrix (M1) protein of influenza A virus

Abstract

The membraneand ribonucleocapsid (RNP)-binding domains of the matrix (Ml) protein of influenza A virus (WSN strain) were partially mapped and characterized by reactivity with monoclonal antibodies (MAb) as well as by proteolytic cleavages and amino acid sequencing of the resulting peptides. Of two peptides formed by formic acid hydrolysis, a 9-kilodalton fragment at the amino-terminal third of the Ml protein was recognized by MAb M2-1C6 (to epitope 1), and a 15-kilodalton fragment at the carboxy-terminal two-thirds was recognized by MAb 289/4 (to epitope 2). Partial cleavage by staphylococcal V8 protease gave rise to a 16-kilodalton peptide, mapping to amino acid 8, which was recognized by MAbs to all three epitopes but rather weakly by MAb 904/6 to epitope 3. These studies suggest that epitope 1 of the Ml protein resides between amino acids 8 and 89, whereas epitopes 2 and possibly 3 are located between amino acids 89 and 141 or somewhat more carboxy distal. The intact Ml protein and its N-terminal 9-and 10-kilodalton peptides generated by formic acid or V8 protease cleavage, respectively, reconstituted with dipalmitoylphosphatidylcholine vesicles, but these N-terminal peptides had little effect on in vitro transcription of the RNP core. In sharp contrast, both intact Ml protein and the C-terminal 15-kilodalton formic acid fragment were able to inhibit viral transcription markedly. Moreover, MAb 289/4 (to epitope 2) reversed this inhibited transcription significantly. These studies suggest that the lipid-binding domain of the Ml protein is located within the amino-terminal third, whereas the site involved in the interaction of the Ml protein with RNP cores is located within the carboxy-terminal

Assembly and budding of influenza virus

“…It is likely that the M1-vRNP complex is formed by the interaction of M1 with the RNA of the vRNP. It has been shown that M1 interacts with the vRNP and inhibits transcription (Watanabe et al, 1996;Ye et al, 1987Ye et al, , 1999. Furthermore, M1 has been shown to bind ssRNA in vitro (Elster et al, 1997) and to vRNP in virusinfected cells (Lopez-Turiso et al, 1990;Ruigrok and Baudin, 1995) and in virus particles (Schulze, 1972), but M1 does not bind to NP expressed alone (Huang et al, 2001;Zhao et al, 1998).…”

Structural Determinants of the Interactions Between Influenza A Virus Matrix Protein M1 and Lipid Membranes

“…C-terminal fragment, aa 165-254) and M1 m (in which the basic residues in the PBD were mutated to alanine residues, 95-AAVALYAALAA-105). Using a similar approach, a qualitative characterization of M1–lipid interaction has previously suggested that the N-terminal domain plays a fundamental role [21], although no consensus was reached regarding the specific regions actually mediating M1–membrane binding [28, 55, 56]. Here, we quantified the binding of the M1 constructs and full-length M1 wt to PS-containing model membranes using a combination of SPR and fluorescence microscopy.…”

Evaluation of a virus derived from MDCK cells infected persistently with influenza A virus as a potential live‐attenuated vaccine candidate in the mouse model

“…This region is flexible and changes conformation easily under different conditions [Arzt et al, 2004]. A monoclonal antibody against an M1 epitope that resides between amino acids 8 and 89 inhibits reconstitution of the M1 protein with the lipid bilayer, suggesting that this region is the lipid-binding domain of the M1 protein [Ye et al, 1987]. Although the precise mechanisms remain to be clarified, the amino acid change at the position 72 is inferred to influence the nuclear import of the IVpi-189 M1 protein by causing loss of flexibility around the lipid-binding domain, altering the three-dimensional structure of the IVpi-189 M1 protein, and/or the amino acid change alters or decreases the membrane binding activity of the M1 protein.…”