Structural heterogeneity of cryotrapped intermediates in the bacterial blue light photoreceptor, photoactive yellow protein

Spencer Anderson*, Vukica Šrajer, Keith Moffat

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

We investigate by X-ray crystallographic techniques the cryotrapped states that accumulate on controlled illumination of the blue light photoreceptor, photoactive yellow protein (PYP), at 110 K in both the wild-type species and its E46Q mutant. These states are related to those that occur during the chromophore isomerization process in the PYP photocycle at room temperature. The structures present in such states were determined at high resolution, 0.95-1.05Å. In both wild type and mutant PYP, the cryotrapped state is not composed of a single, quasitransition state structure but rather of a heterogeneous mixture of three species in addition to the ground state structure. We identify and refine these three photoactivated species under the assumption that the structural changes are limited to simple isomerization events of the chromophore that otherwise retains chemical bonding similar to that in the ground state. The refined chromophore models are essentially identical in the wild type and the E46Q mutant, which implies that the early stages of their photocycle mechanisms are the same.

Original languageEnglish (US)
Pages (from-to)7-14
Number of pages8
JournalPhotochemistry and Photobiology
Volume80
Issue number1
DOIs
StatePublished - Jul 2004

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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