Vaccinia Virus H3 Envelope Protein, a Major Target of Neutralizing Antibodies, Exhibits a Glycosyltransferase Fold and Binds UDP-Glucose
The highly conserved H3 poxvirus protein is a major target of the human antibody response against poxviruses and is likely a key contributor to protection against infection. Here, we present the crystal structure of H3 from vaccinia virus at a 1.9-Å resolution. H3 looks like a glycosyltransferase, a family of enzymes that transfer carbohydrate molecules to a variety of acceptor substrates. Like glycosyltransferases, H3 binds UDP-glucose, as shown by saturation transfer difference (STD) nuclear magnetic resonance (NMR) spectroscopy, and this binding requires Mg2+. Mutation of the glycosyltransferase-like metal ion binding motif in H3 greatly diminished its binding to UDP-glucose. We found by flow cytometry that H3 binds to the surface of human cells but does not bind well to cells that are deficient in surface glycosaminoglycans. STD NMR experiments using a heparin sulfate decasaccharide confirmed that H3 binds heparin sulfate. We propose that a surface of H3 with an excess positive charge may be the binding site for heparin. Heparin binding and glycosyltransferase activity may be involved in the function of H3 in the poxvirus life cycle.
Crystal structure of the human sterol transporter ABCG5/ABCG8
ATP binding cassette (ABC) transporters play critical roles in maintaining sterol balance in higher eukaryotes. The ABCG5/ ABCG8 heterodimer (G5G8) mediates excretion of neutral sterols in liver and intestines.
SBC is pleased to announce the introduction of a Pilatus 3 X 6M detector into the User Program at beamline 19-ID.
Data collected by our users has been of outstanding quality.
19-BM Rebotic sample mounter available
A robot is now available for use at beamline 19-BM. The sample dewar accommodates ten Unipuck magazines; pins must be 18mm in length and use either SSRL or ALS bases. Experienced users may now request remote access to 19-BM when applying for beamtime.
Beginning August 01, 2015 the Midwest Center for Structural Genomics (MCSG) will start accepting applications for access to the MCSG User Resource.
MCSG's structure determination platform is well established, and combines technologies, robotics and expertise for gene cloning, protein production, and crystallization, as well as biochemical and biophysical characterization.