Myristoylation drives dimerization of matrix protein from mouse mammary tumor virus

0458491 - ÚOCHB 2017 RIV GB eng J - Journal Article
Doležal, Michal - Zábranský, Aleš - Dostál, Jiří - Vaněk, O. - Brynda, Jiří - Lepšík, Martin - Hadravová, Romana - Pichová, Iva
Myristoylation drives dimerization of matrix protein from mouse mammary tumor virus.
Retrovirology. Roč. 13, Jan 5 (2016), č. článku 2. E-ISSN 1742-4690
R&D Projects: GA MŠMT LO1302; GA MŠMT(CZ) LO1304; GA ČR GBP208/12/G016
Institutional support: RVO:61388963
Keywords : dimerization * matrix protein * MMTV * molecular dynamics * mouse mammary tumor virus * myristoylation
Subject RIV: CE - Biochemistry
Impact factor: 3.867, year: 2016
http://retrovirology.biomedcentral.com/articles/10.1186/s12977-015-0235-8

Background: Myristoylation of the matrix (MA) domain mediates the transport and binding of Gag polyproteins to the plasma membrane (PM) and is required for the assembly of most retroviruses. In betaretroviruses, which assemble immature particles in the cytoplasm, myristoylation is dispensable for assembly but is crucial for particle transport to the PM. Oligomerization of HIV-1 MA stimulates the transition of the myristoyl group from a sequestered to an exposed conformation, which is more accessible for membrane binding. However, for other retroviruses, the effect of MA oligomerization on myristoyl group exposure has not been thoroughly investigated.
Results: Here, we demonstrate that MA from the betaretrovirus mouse mammary tumor virus (MMTV) forms dimers in solution and that this process is stimulated by its myristoylation. The crystal structure of N-myristoylated MMTV MA, determined at 1.57 angstrom resolution, revealed that the myristoyl groups are buried in a hydrophobic pocket at the dimer interface and contribute to dimer formation. Interestingly, the myristoyl groups in the dimer are mutually swapped to achieve energetically stable binding, as documented by molecular dynamics modeling. Mutations within the myristoyl binding site resulted in reduced MA dimerization and extracellular particle release.
Conclusions: Based on our experimental, structural, and computational data, we propose a model for dimerization of MMTV MA in which myristoyl groups stimulate the interaction between MA molecules. Moreover, dimer-forming MA molecules adopt a sequestered conformation with their myristoyl groups entirely buried within the interaction interface. Although this differs from the current model proposed for lentiviruses, in which oligomerization of MA triggers exposure of myristoyl group, it appears convenient for intracellular assembly, which involves no apparent membrane interaction and allows the myristoyl group to be sequestered during oligomerization.
Permanent Link: http://hdl.handle.net/11104/0258760