Abstract

Light absorbed by the photosynthetic pigments induces charge separation in photosystems I (PSI) driving electron transport from water to NADP+. One of the early electron acceptors in photosystem I (PSI) is a very low potential iron-sulfur cluster, Fx. Understanding the mechanism of action of PSI requires a knowledge of the structure of Fx and the structural changes induced by the electron transfer process through Fx. Although many of the components of PSI and their function are known, there is a little information about their special arrangement and their interaction with the amino acid residues of the polypeptide chains. Site directed mutations were performed on the psaB gene from the cyanobacterium on the two conserved cysteines 556 and 565. Each cysteine was substituted once with serine and once with histidine resulting in overall of four mutants of the B subunit, these cysteines are proposed to serve as two of the four ligands that binds the iron in Fx. We present the X-ray absorption fine structure (XAFS) spectra of the mutated Fx in comparison to the native Fx spectra. The XAFS analysis of the mutated metal site provides a direct assignment of the different ligands.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
5P41RR001633-14
Application #
5223479
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
14
Fiscal Year
1996
Total Cost
Indirect Cost

  Publications

Masip, Lluis; Pan, Jonathan L; Haldar, Suranjana et al. (2004) An engineered pathway for the formation of protein disulfide bonds. Science 303:1185-9
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Uchida, Takeshi; Takamoto, Keiji; He, Qin et al. (2003) Multiple monovalent ion-dependent pathways for the folding of the L-21 Tetrahymena thermophila ribozyme. J Mol Biol 328:463-78
Taylor, Colleen M; Watton, Stephen P; Bryngelson, Peter A et al. (2003) Inner-sphere complexation of cobalt(II) 2,9-dimethyl-1,10-phenanthroline ([Co(neo)]2+) with commercial and sol-gel derived silica gel surfaces. Inorg Chem 42:312-20
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Swisher, Jennifer F; Su, Linhui J; Brenowitz, Michael et al. (2002) Productive folding to the native state by a group II intron ribozyme. J Mol Biol 315:297-310
Dhavan, Gauri M; Crothers, Donald M; Chance, Mark R et al. (2002) Concerted binding and bending of DNA by Escherichia coli integration host factor. J Mol Biol 315:1027-37

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