Noncanonical Photocycle Initiation Dynamics of the Photoactive Yellow Protein (PYP) Domain of the PYP-Phytochrome-Related (Ppr) Photoreceptor

J Phys Chem Lett. 2016 Dec 15;7(24):5212-5218. doi: 10.1021/acs.jpclett.6b02253. Epub 2016 Dec 5.

Abstract

The photoactive yellow protein (PYP) from Halorhodospira halophila (Hhal) is a bacterial photoreceptor and model system for exploring functional protein dynamics. We report ultrafast spectroscopy experiments that probe photocycle initiation dynamics in the PYP domain from the multidomain PYP-phytochrome-related photoreceptor from Rhodospirillum centenum (Rcen). As with Hhal PYP, Rcen PYP exhibits similar excited-state dynamics; in contrast, Rcen PYP exhibits altered photoproduct ground-state dynamics in which the primary I0 intermediate as observed in Hhal PYP is absent. This property is attributed to a tighter, more sterically constrained binding pocket around the p-coumaric acid chromophore due to a change in the Rcen PYP protein structure that places Phe98 instead of Met100 in contact with the chromophore. Hence, the I0 state is not a necessary step for the initiation of productive PYP photocycles and the ubiquitously studied Hhal PYP may not be representative of the broader PYP family of photodynamics.

MeSH terms

  • Bacterial Proteins / chemistry*
  • Coumaric Acids
  • Halorhodospira halophila*
  • Photoreceptors, Microbial / chemistry*
  • Phytochrome / metabolism
  • Propionates
  • Spectrum Analysis*

Substances

  • Bacterial Proteins
  • Coumaric Acids
  • Photoreceptors, Microbial
  • Propionates
  • photoactive yellow protein, Bacteria
  • Phytochrome
  • p-coumaric acid