IUCrJ (Nov 2021)

Observation of substrate diffusion and ligand binding in enzyme crystals using high-repetition-rate mix-and-inject serial crystallography

  • Suraj Pandey,
  • George Calvey,
  • Andrea M. Katz,
  • Tek Narsingh Malla,
  • Faisal H. M. Koua,
  • Jose M. Martin-Garcia,
  • Ishwor Poudyal,
  • Jay-How Yang,
  • Mohammad Vakili,
  • Oleksandr Yefanov,
  • Kara A. Zielinski,
  • Sasa Bajt,
  • Salah Awel,
  • Katarina Doerner,
  • Matthias Frank,
  • Luca Gelisio,
  • Rebecca Jernigan,
  • Henry Kirkwood,
  • Marco Kloos,
  • Jayanath Koliyadu,
  • Valerio Mariani,
  • Mitchell D. Miller,
  • Grant Mills,
  • Garrett Nelson,
  • Jose L. Olmos Jr,
  • Alireza Sadri,
  • Tokushi Sato,
  • Alexandra Tolstikova,
  • Weijun Xu,
  • Abbas Ourmazd,
  • John C. H. Spence,
  • Peter Schwander,
  • Anton Barty,
  • Henry N. Chapman,
  • Petra Fromme,
  • Adrian P. Mancuso,
  • George N. Phillips Jr,
  • Richard Bean,
  • Lois Pollack,
  • Marius Schmidt

DOI
https://doi.org/10.1107/S2052252521008125
Journal volume & issue
Vol. 8, no. 6
pp. 878 – 895

Abstract

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Here, we illustrate what happens inside the catalytic cleft of an enzyme when substrate or ligand binds on single-millisecond timescales. The initial phase of the enzymatic cycle is observed with near-atomic resolution using the most advanced X-ray source currently available: the European XFEL (EuXFEL). The high repetition rate of the EuXFEL combined with our mix-and-inject technology enables the initial phase of ceftriaxone binding to the Mycobacterium tuberculosis β-lactamase to be followed using time-resolved crystallography in real time. It is shown how a diffusion coefficient in enzyme crystals can be derived directly from the X-ray data, enabling the determination of ligand and enzyme–ligand concentrations at any position in the crystal volume as a function of time. In addition, the structure of the irreversible inhibitor sulbactam bound to the enzyme at a 66 ms time delay after mixing is described. This demonstrates that the EuXFEL can be used as an important tool for biomedically relevant research.

Keywords