Mutations in both sides of the photosystem I reaction center identify the phylloquinone observed by electron paramagnetic resonance spectroscopy

Boudreaux, Brent, MacMillan, Fraser ORCID: https://orcid.org/0000-0002-2410-4790, Teutloff, Christian, Agalarov, Rufat, Gu, Feifei, Grimaldi, Stéphane, Bittl, Robert, Brettel, Klaus and Redding, Kevin (2001) Mutations in both sides of the photosystem I reaction center identify the phylloquinone observed by electron paramagnetic resonance spectroscopy. Journal of Biological Chemistry, 276 (40). pp. 37299-37306. ISSN 0021-9258

Full text not available from this repository.

Abstract

The core of photosystem I (PS1) is composed of the two related integral membrane polypeptides, PsaA and PsaB, which bind two symmetrical branches of cofactors, each consisting of two chlorophylls and a phylloquinone, that potentially link the primary electron donor and the tertiary acceptor. In an effort to identify amino acid residues near the phylloquinone binding sites, all tryptophans and histidines that are conserved between PsaA and PsaB in the region of the 10th and 11th transmembrane alpha -helices were mutated in Chlamydomonas reinhardtii. The mutant PS1 reaction centers appear to assemble normally and possess photochemical activity. An electron paramagnetic resonance (EPR) signal attributed to the phylloquinone anion radical(A(1)(-)) can be observed either transiently or after illumination of reaction centers with pre-reduced iron-sulfur clusters. Mutation of PsaA-Trp(693) to Phe resulted in an inability to photo-accumulate A(1)(-), whereas mutation of the analogous tryptophan in PsaB (PsaB-Trp(673)) did not produce this effect. The PsaA-W693F mutation also produced spectral changes in the time-resolved EPR spectrum of the P-700(+) A(1)(-) radical pair, whereas the analogous mutation in PsaB had no observable effect. These observations indicate that the A(1)(-) phylloquinone radical observed by EPR occupies the phylloquinone-binding site containing PsaA-Trp(693). However, mutation of either tryptophan accelerated charge recombination from the terminal Fe-S clusters.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry (former - to 2024)
UEA Research Groups:	Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Chemistry of Light and Energy
Depositing User:	Rachel Smith
Date Deposited:	19 Jul 2011 11:08
Last Modified:	24 Sep 2024 10:21
URI:	https://ueaeprints.uea.ac.uk/id/eprint/33884
DOI:	10.1074/jbc.M102327200

Actions (login required)

View Item