Myxovirus resistent proteine 1

The myxovirus resistance protein (Mx protein, MxA in humans) is an antiviral protein that plays a central role in the innate immune response - specifically in response to interferon stimulation. It is encoded by the MX1 gene (MX1 stands for: MX Dynamin Like GTPase 1) located on chromosome 21q22.3. Alternative splicing leads to several transcript variants. There is a related gene located next to this gene on chromosome 21. There are also several pseudogenes located in a cluster on chromosome 4. MxA is considered a marker for interferon activity, e.g. in viral infections or autoimmune diseases such as SLE. In diagnostic tests, MxA expression is used as an indicator of viral infection (e.g. to distinguish viral infections from bacterial infections).

General properties:

• Name: Myxovirus resistance protein A (MxA in humans, Mx1/Mx2 in mice)
• Gene: encoded by interferon-stimulated genes (ISGs)
• Induction: MxA is induced by type I interferons (especially IFN-alpha and IFN-beta)
• Localization: MxA is found in the cytoplasm; in some species also in the nucleus

Structure:

• GTPase: MxA proteins belong to the dynamin family of GTPases (these hydrolyze GTP)
• MxA proteins have an N-terminal GTPase domain and a C-terminal effector domain
• MxA proteins can form oligomers (several proteins join together to form a complex)

Function:

• The interferon-induced "dynamin-like GTPase" (myxoma resistance protein 1) exhibits antiviral activity against a variety of RNA viruses and some DNA viruses. The target viruses include negative-stranded RNA viruses and HBV by binding and inactivating their ribonucleocapsid. The enzyme can also antagonize the replication of Reoviridae and Asfarviridae. The enzyme inhibits the replication of Thogoto virus (THOV) by preventing the nuclear incorporation of viral nucleocapsids; inhibits the replication of La Crosse virus (LACV) by binding the viral nucleoprotein into perinuclear complexes, thus preventing genome amplification, budding and egress; inhibits influenza A virus (IAV) replication by reducing or delaying NP synthesis and blocking endocytic trafficking of incoming virus particles.

• Other viruses against which MxA is effective:

• Thogotoviruses, Bunyaviruses, SARS-CoV-2 (partially inhibitory)

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