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Matrix and Matrix long proteins N-terminal This entry represents the N-terminal fragment of family members such as the Matrix (Mx) and Matrix protein long (ML) proteins. They are found in Thogoto virus (THOV), a tick-transmitted orthomyxovirus with a genome consisting of six single-stranded RNA segments that encode seven structural proteins. Matrix proteins of the family Orthomyxoviridae are major structural components of the viral capsid, located below the viral lipid membrane and provide protection for viral ribonucleoproteins (vRNPs). They serve as a major participant during the processes of virus invasion and budding. Furthermore, they play specific roles throughout the viral life cycle, usually by interacting with other viral components or host cellular proteins. ML protein, an extended version of the viral M protein, is a viral IFN antagonist. ML is essential for virus growth and pathogenesis in an IFN-competent host. In the presence of ML the activation and/or action of the interferon regulatory factor-3 (IRF-3) is severely affected. This effect depends on direct interaction of ML with the transcription factor IIB (TFIIB). ML suppresses IRF-7 in a similar manner as it suppresses IRF-3. Studies have revealed that ML associates with IRF-7 and prevents IRF-7 dimerization and interaction with TRAF6. Structural analysis revealed that N-terminal fragment of M protein (MN) undergoes conformational changes that result in specific, pH-dependent inter-molecular interactions. Comparison of THOV MN and influenza A virus (IAV) MN region, showed low sequence identity. However, superimposition of the two structures in neutral condition, showed that both matrix proteins contain nine helices connected with same topology. Since the matrix layer of IAV disassembles in acidic endosome at the beginning of infection and repacks in the neutral cytoplasm, a change of pH might be a key regulator for the capsid assembly/disassembly transition during these processes. Hence, pH-dependent conformational transition model was studied in THOV MN, where interactions such as hydrogen bonds and hydrophobic interactions are suggested to be involved in THOV matrix assembly. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",