Restriction of HIV-1 requires the N-terminal region of MxB as a capsid-binding motif but not as a nuclear localization signal

Bianca Schulte, Cindy Buffone, Silvana Opp, Francesca Di Nunzio, Daniel Augusto De Souza Aranha Vieira, Alberto Brandariz-Nuñez, Felipe Diaz-Griffero

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

The interferon alpha (IFN-α)-inducible restriction factor MxB blocks HIV-1 infection after reverse transcription but prior to integration. Fate-of-capsid experiments have correlated the ability of MxB to block HIV-1 infection with stabilization of viral cores during infection. We previously demonstrated that HIV-1 restriction by MxB requires capsid binding and oligomerization. Deletion and gain-of-function experiments have mapped the HIV-1 restriction ability of MxB to its N-terminal 25 amino acids. This report reveals that the N-terminal 25 amino acids of MxB exhibit two separate functions: (i) the ability of MxB to bind to HIV-1 capsid and (ii) the nuclear localization signal of MxB, which is important for the ability of MxB to shuttle into the nucleus. To understand whether MxB restriction of HIV-1 requires capsid binding and/or nuclear localization, we genetically separated these two functions and evaluated their contributions to restriction. Our experiments demonstrated that the 11RRR13 motif is important for the ability of MxB to bind capsid and to restrict HIV-1 infection. These experiments suggested that capsid binding is necessary for the ability of MxB to block HIV-1 infection. Separately from the capsid binding function of MxB, we found that residues 20KY21 regulate the ability of the N-terminal 25 amino acids of MxB to function as a nuclear localization signal; however, the ability of the N-terminal 25 amino acids to function as a nuclear localization signal was not required for restriction.

Original languageEnglish (US)
Pages (from-to)8599-8610
Number of pages12
JournalJournal of virology
Volume89
Issue number16
DOIs
StatePublished - Jan 1 2015

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

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