title: The N-terminus of murine leukaemia virus p12 protein is required for mature core stability.
abstract: The murine leukaemia virus (MLV) gag gene encodes a small protein called p12 that is essential for the early steps of viral replication. The N- and C-terminal regions of p12 are sequentially acting domains, both required for p12 function. Defects in the C-terminal domain can be overcome by introducing a chromatin binding motif into the protein. However, the function of the N-terminal domain remains unknown. Here, we undertook a detailed analysis of the effects of p12 mutation on incoming viral cores. We found that both reverse transcription complexes and isolated mature cores from N-terminal p12 mutants have altered capsid complexes compared to wild type virions. Electron microscopy revealed that mature N-terminal p12 mutant cores have different morphologies, although immature cores appear normal. Moreover, in immunofluorescent studies, both p12 and capsid proteins were lost rapidly from N-terminal p12 mutant viral cores after entry into target cells. Importantly, we determined that p12 binds directly to the MLV capsid lattice. However, we could not detect binding of an N-terminally altered p12 to capsid. Altogether, our data imply that p12 stabilises the mature MLV core, preventing premature loss of capsid, and that this is mediated by direct binding of p12 to the capsid shell. In this manner, p12 is also retained in the pre-integration complex where it facilitates tethering to mitotic chromosomes. These data also explain our previous observations that modifications to the N-terminus of p12 alter the ability of particles to abrogate restriction by TRIM5alpha and Fv1, factors that recognise viral capsid lattices.
authors.affiliation: Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Wight
authors.affiliation: Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
authors.forename: Virginie C
authors.initials: VC
authors.lastname: Boucherit
authors.affiliation: Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
authors.forename: Madushi
authors.initials: M
authors.lastname: Wanaguru
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Efrat
authors.initials: E
authors.lastname: Elis
authors.affiliation: Division of Developmental Neurobiology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
authors.forename: Elizabeth M A
authors.initials: EM
authors.lastname: Hirst
authors.affiliation: Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
authors.forename: Wilson
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Ehrlich
authors.affiliation: Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Bacharach
authors.affiliation: Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, United Kingdom.
authors.forename: Kate N
authors.initials: KN
authors.lastname: Bishop
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002213:Capsid / Q000378:metabolism* / Q000648:ultrastructure; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002875:Chromosomes; D015683:Gene Products, gag / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009052:Leukemia Virus, Murine / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D012192:Retroviridae Infections / Q000821:virology*; D048348:Reverse Transcription; D016415:Sequence Alignment; D014771:Virion; D014779:Virus Replication
chemical_list: D036022:Capsid Proteins; D015683:Gene Products, gag; D011994:Recombinant Proteins