Overlapping effector interfaces define the multiple functions of the HIV-1 Nef polyproline helix Public Deposited

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Creator
  • Foster, John L
    • Affiliation: School of Medicine, Division of Infectious Diseases, UNC Center for AIDS Research
  • Baugh, Laura L
    • Other Affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Y9.206, Dallas, TX 75390, USA
  • Garcia, J. Victor
    • Affiliation: School of Medicine, Division of Infectious Diseases, UNC Center for AIDS Research
  • Kuo, Lillian S
    • Other Affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Y9.206, Dallas, TX 75390, USA
  • Watkins, Richard L
    • Affiliation: School of Medicine, Division of Infectious Diseases, UNC Center for AIDS Research
  • Liu, Mingjie
    • Affiliation: School of Medicine, Division of Infectious Diseases, UNC Center for AIDS Research
  • Denial, Sarah J
    • Affiliation: School of Medicine, Division of Infectious Diseases, UNC Center for AIDS Research
Abstract
  • Background: HIV-1 Nef is a multifunctional protein required for full pathogenicity of the virus. As Nef has no known enzymatic activity, it necessarily functions through protein-protein interaction interfaces. A critical Nef protein interaction interface is centered on its polyproline segment (P69VRPQVPLRP78) which contains the helical SH3 domain binding protein motif, PXXPXR. We hypothesized that any Nef-SH3 domain interactions would be lost upon mutation of the prolines or arginine of PXXPXR. Further, mutation of the non-motif “X” residues, (Q73, V74, and L75) would give altered patterns of inhibition for different Nef/SH3 domain protein interactions. Results: We found that mutations of either of the prolines or the arginine of PXXPXR are defective for Nef-Hck binding, Nef/activated PAK2 complex formation and enhancement of virion infectivity (EVI). Mutation of the non-motif “X” residues (Q, V and L) gave similar patterns of inhibition for Nef/activated PAK2 complex formation and EVI which were distinct from the pattern for Hck binding. These results implicate an SH3 domain containing protein other than Hck for Nef/activated PAK2 complex formation and EVI. We have also mutated Nef residues at the N-and C-terminal ends of the polyproline segment to explore interactions outside of PXXPXR. We discovered a new locus GFP/F (G67, F68, P69 and F90) that is required for Nef/activated PAK2 complex formation and EVI. MHC Class I (MHCI) downregulation was only partially inhibited by mutating the PXXPXR motif residues, but was fully inhibited by mutating the C-terminal P78. Further, we observed that MHCI downregulation strictly requires G67 and F68. Our mutational analysis confirms the recently reported structure of the complex between Nef, AP-1 μ1 and the cytoplasmic tail of MHCI, but does not support involvement of an SH3 domain protein in MHCI downregulation. Conclusion: Nef has evolved to be dependent on interactions with multiple SH3 domain proteins. To the N- and C- terminal sides of the polyproline helix are multifunctional protein interaction sites. The polyproline segment is also adapted to downregulate MHCI with a non-canonical binding surface. Our results demonstrate that Nef polyproline helix is highly adapted to directly interact with multiple host cell proteins.
Date of publication
Identifier
  • doi:10.1186/1742-4690-9-47
  • 22651890
Resource type
  • Article
Rights statement
  • In Copyright
Rights holder
  • Lillian S Kuo et al.; licensee BioMed Central Ltd.
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Journal title
  • Retrovirology
Journal volume
  • 9
Journal issue
  • 1
Page start
  • 47
Language
  • English
Is the article or chapter peer-reviewed?
  • Yes
ISSN
  • 1742-4690
Bibliographic citation
  • Retrovirology. 2012 May 31;9(1):47
Access
  • Open Access
Publisher
  • BioMed Central Ltd
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