Room-temperature serial synchrotron crystallography of apo PTP1B

Abstract

Room-temperature X-ray crystallography provides unique insights into protein conformational heterogeneity, but a common hurdle is obtaining sufficiently large protein crystals. Serial synchrotron crystallography (SSX) helps address this hurdle by allowing the use of many medium- to small-sized crystals. We have used a recently introduced serial sample support chip system to obtain the first SSX structure of a human phosphatase, specifically Protein Tyrosine Phosphatase 1B (PTP1B) in the unliganded (apo) state. In previous apo room-temperature structures, the active site and allosteric sites adopted alternate conformations, including open and closed conformations for the active-site WPD loop and for a distal allosteric site. By contrast, in our SSX structure, the active site is best fit with a single conformation, but the distal allosteric site is best fit with alternate conformations. This observation argues for additional nuance in interpreting the nature of allosteric coupling in this protein. Overall, our results illustrate the promise of serial methods for room-temperature crystallography, as well as future avant-garde crystallography experiments, for PTP1B and other proteins.