Mix-and-inject XFEL crystallography reveals gated conformational dynamics during enzyme catalysis
- Univ. of Nebraska, Lincoln, NE (United States)
- Friedrich-Alexander Univ., Erlangen (Germany)
- Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Univ. of Puerto Rico, Mayaguez (Puerto Rico)
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS)
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS) and Photon Ultrafast Laser Science and Engineering Inst. (PULSE)
- SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. of California, San Francisco, CA (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. of California, San Francisco, CA (United States)
How changes in enzyme structure and dynamics facilitate passage along the reaction coordinate is a fundamental unanswered question. Here, we use time-resolved mix-and-inject serial crystallography (MISC) at an X-ray free electron laser (XFEL), ambient-temperature X-ray crystallography, computer simulations, and enzyme kinetics to characterize how covalent catalysis modulates isocyanide hydratase (ICH) conformational dynamics throughout its catalytic cycle. We visualize this previously hypothetical reaction mechanism, directly observing formation of a thioimidate covalent intermediate in ICH microcrystals during catalysis. We report, ICH exhibits a concerted helical displacement upon active-site cysteine modification that is gated by changes in hydrogen bond strength between the cysteine thiolate and the backbone amide of the highly strained Ile152 residue. These catalysis-activated motions permit water entry into the ICH active site for intermediate hydrolysis. Mutations at a Gly residue (Gly150) that modulate helical mobility reduce ICH catalytic turnover and alter its pre-steady-state kinetic behavior, establishing that helical mobility is important for ICH catalytic efficiency. These results demonstrate that MISC can capture otherwise elusive aspects of enzyme mechanism and dynamics in microcrystalline samples, resolving long-standing questions about the connection between nonequilibrium protein motions and enzyme catalysis.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL) and Linac Coherent Light Source (LCLS); Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; USDOE Laboratory Directed Research and Development (LDRD) Program; National Institutes of Health (NIH); National Science Foundation (NSF); David and Lucile Packard Foundation; University of California (UC) Office of the President Laboratory Fees Research Program; USDOE National Nuclear Security Administration (NNSA); Deutsche Forschungsgemeinschaft (DFG); Nebraska Tobacco Settlement Biomedical Research Development Fund; USDOE Office of Science (SC), Biological and Environmental Research (BER); National Institute of General Medical Sciences (NIGMS); Planck Institute for Medical Research
- Grant/Contract Number:
- AC02-76SF00515; AC02-06CH11357
- OSTI ID:
- 1604575
- Alternate ID(s):
- OSTI ID: 1633800
OSTI ID: 1659760
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 51 Vol. 116; ISSN 0027-8424
- Publisher:
- National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Shining light on cysteine modification: connecting protein conformational dynamics to catalysis and regulation
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journal | June 2019 |