2XG7

Crystal Structure of BST2-Tetherin Ectodomain expressed in HEK293T cells

Summary for 2XG7

• Entry DOI: 10.2210/pdb2xg7/pdb
• Related: 2X7A
• Descriptor: BONE MARROW STROMAL ANTIGEN 2, 2-acetamido-2-deoxy-beta-D-glucopyranose (2 entities in total)
• Functional Keywords: innate immune factor, antiviral protein
• Biological source: HOMO SAPIENS (HUMAN)
• Cellular location: Golgi apparatus, trans-Golgi network: Q10589
• Total number of polymer chains: 2
• Total formula weight: 23370.21

Authors

Steiner, R.A. (deposition date: 2010-05-31, release date: 2010-10-13, Last modification date: 2024-10-09)

Primary citation

Schubert, H.L.,Zhai, Q.,Sandrin, V.,Eckert, D.M.,Garcia-Maya, M.,Saul, L.,Sundquist, W.I.,Steiner, R.A.,Hill, C.P.
Structural and Functional Studies on the Extracellular Domain of Bst2/Tetherin in Reduced and Oxidized Conformations.
Proc.Natl.Acad.Sci.USA, 107:17951-, 2010

PubMed Abstract: HIV-1 and other enveloped viruses can be restricted by a host cellular protein called BST2/tetherin that prevents release of budded viruses from the cell surface. Mature BST2 contains a small cytosolic region, a predicted transmembrane helix, and an extracellular domain with a C-terminal GPI anchor. To advance understanding of BST2 function, we have determined a 2.6 Å crystal structure of the extracellular domain of the bacterially expressed recombinant human protein, residues 47-152, under reducing conditions. The structure forms a single long helix that associates as a parallel dimeric coiled coil over its C-terminal two-thirds, while the N-terminal third forms an antiparallel four-helix bundle with another dimer, creating a global tetramer. We also report the 3.45 Å resolution structure of BST2(51-151) prepared by expression as a secreted protein in HEK293T cells. This oxidized construct forms a dimer in the crystal that is superimposable with the reduced protein over the C-terminal two-thirds of the molecule, and its N terminus suggests pronounced flexibility. Hydrodynamic data demonstrated that BST2 formed a stable tetramer under reducing conditions and a dimer when oxidized to form disulfide bonds. A mutation that selectively disrupted the tetramer (L70D) increased protein expression modestly but only reduced antiviral activity by approximately threefold. Our data raise the possibility that BST2 may function as a tetramer at some stage, such as during trafficking, and strongly support a model in which the primary functional state of BST2 is a parallel disulfide-bound coiled coil that displays flexibility toward its N terminus.

PubMed: 20880831
DOI: 10.1073/PNAS.1008206107

Experimental method

X-RAY DIFFRACTION (3.45 Å)