Confinement in crystal lattice alters entire photocycle pathway of the Photoactive Yellow Protein

Nat Commun. 2020 Aug 25;11(1):4248. doi: 10.1038/s41467-020-18065-9.

Abstract

Femtosecond time-resolved crystallography (TRC) on proteins enables resolving the spatial structure of short-lived photocycle intermediates. An open question is whether confinement and lower hydration of the proteins in the crystalline state affect the light-induced structural transformations. Here, we measured the full photocycle dynamics of a signal transduction protein often used as model system in TRC, Photoactive Yellow Protein (PYP), in the crystalline state and compared those to the dynamics in solution, utilizing electronic and vibrational transient absorption measurements from 100 fs over 12 decades in time. We find that the photocycle kinetics and structural dynamics of PYP in the crystalline form deviate from those in solution from the very first steps following photon absorption. This illustrates that ultrafast TRC results cannot be uncritically extrapolated to in vivo function, and that comparative spectroscopic experiments on proteins in crystalline and solution states can help identify structural intermediates under native conditions.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism*
  • Bacterial Proteins / radiation effects
  • Crystallography, X-Ray / methods*
  • Kinetics
  • Light
  • Molecular Structure
  • Photochemical Processes
  • Photoreceptors, Microbial / chemistry*
  • Photoreceptors, Microbial / metabolism*
  • Photoreceptors, Microbial / radiation effects
  • Protein Conformation
  • Spectrum Analysis

Substances

  • Bacterial Proteins
  • Photoreceptors, Microbial
  • photoactive yellow protein, Bacteria