title: Neutron and X-ray structural studies of short hydrogen bonds in photoactive yellow protein (PYP).
abstract: Photoactive yellow protein (PYP) from Halorhodospira halophila is a soluble 14 kDa blue-light photoreceptor. It absorbs light via its para-coumaric acid chromophore (pCA), which is covalently attached to Cys69 and is believed to be involved in the negative phototactic response of the organism to blue light. The complete structure (including H atoms) of PYP has been determined in D(2)O-soaked crystals through the application of joint X-ray (1.1 A) and neutron (2.5 A) structure refinement in combination with cross-validated maximum-likelihood simulated annealing. The resulting XN structure reveals that the phenolate O atom of pCA accepts deuterons from Glu46 O(epsilon2) and Tyr42 O(eta) in two unusually short hydrogen bonds. This arrangement is stabilized by the donation of a deuteron from Thr50 O(gamma1) to Tyr42 O(eta). However, the deuteron position between pCA and Tyr42 is only partially occupied. Thus, this atom may also interact with Thr50, possibly being disordered or fluctuating between the two bonds.
authors.affiliation: Bioscience Division, Los Alamos National Laboratory, M888, Los Alamos, NM 87545, USA. zfisher@lanl.gov
authors.forename: S Z
authors.initials: SZ
authors.lastname: Fisher
authors.forename: S
authors.initials: S
authors.lastname: Anderson
authors.forename: R
authors.initials: R
authors.lastname: Henning
authors.forename: K
authors.initials: K
authors.lastname: Moffat
authors.forename: P
authors.initials: P
authors.lastname: Langan
authors.forename: P
authors.initials: P
authors.lastname: Thiyagarajan
authors.forename: A J
authors.initials: AJ
authors.lastname: Schultz
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D003373:Coumaric Acids / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D017666:Deuterium Oxide / Q000737:chemistry; D020607:Halorhodospira halophila / Q000737:chemistry* / Q000235:genetics; D006860:Hydrogen Bonding; D008958:Models, Molecular; D033363:Neutron Diffraction; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000235:genetics; D011422:Propionates; D011522:Protons; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D003373:Coumaric Acids; D020283:Photoreceptors, Microbial; D011422:Propionates; D011522:Protons; D011994:Recombinant Proteins; C050162:photoactive yellow protein, Bacteria; C495469:p-coumaric acid; D017666:Deuterium Oxide