Figure 3.
X-ray crystal structure of the HIV-1 Nef core in complex with the Hck SH3-SH2 regulatory region. The overall structure is shown on the left, which crystallized as a dimer of Nef·SH3-SH2 complexes. The surfaces of the Nef core monomers are rendered in blue (NefA) and green (NefB), respectively. The SH3-SH2 subunits associated with each Nef monomer are shown as ribbons, with SH3-SH2B in the foreground (SH2 in blue, SH3 in red). The SH3-SH2A subunit is in the background (SH2 in light blue, SH3 in pink) with the second SH3 domain partially hidden. A close-up view of one Nef interface is shown on the right, with the Nef PxxPxR motif (orange) contacting the SH3 surface via Pro-72 and Pro-75, with Arg-77 making an ionic contact with SH3 RT loop Asp-100. Unique to this complex is a second polar contact between SH3 RT loop Glu-94 and Arg-105 from the opposing Nef monomer. Details of the unique Nef homodimer interface found in this structure are highlighted in Fig. 6. Modeling was performed with PyMOL using the crystal coordinates of the HIV-1 Nef core in complex with the Hck SH3-SH2 domain (PDB code 4U5W).