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Photosynth Res. 2017 Dec;134(3):317-328. doi: 10.1007/s11120-017-0446-z. Epub 2017 Oct 3.

Identification of the ferredoxin interaction sites on ferredoxin-dependent glutamate synthase from Synechocystis sp. PCC 6803.

Author information

1
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX, 79409-1061, USA.
2
Center for Biotechnology and Genomics, Texas Tech University, Lubbock, TX, 79409-3132, USA.
3
Immunology and Molecular Microbiology, Texas Tech University Health Science Center, Lubbock, TX, 79430-6591, USA.
4
Depuy Synthes Companies, 1302 Wrights Lane East, West Chester, PA, 19380, USA.
5
Department of Biochemistry and Molecular Biology, Rosalind Franklin University of Medicine and Science, North Chicago, Illinoi, 60064, USA.
6
Departments of Internal Medicine and Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, 75390-9038, USA. richard.wynn@utsouthwestern.edu.
7
Department of Cell Physiology and Molecular Biophysics, Texas Tech Health Science Center, Lubbock, TX, 79430-6551, USA.

Abstract

Based on in silico docking methods, five amino acids in glutamate synthase (Gln-467, His-1144, Asn-1147, Arg-1162, and Trp-676) likely constitute key binding residues in the interface of a glutamate synthase:ferredoxin complex. Although all interfacial mutants studied showed the ability to form a complex under low ionic strength, these docking mutations showed significantly less ferredoxin-dependent activities, while still retaining enzymatic activity. Furthermore, isothermal titration calorimetry showed a possible 1:2 molar ratio between the wild-type glutamate synthase and ferredoxin. However, each of our interfacial mutants showed only a 1:1 complex with ferredoxin, suggesting that the mutations directly affect the glutamate synthase:ferredoxin heterodimer interface.

KEYWORDS:

Electrostatic interactions; Ferredoxin; Flavin mononucleotide (FMN); Glutamate synthase; In silico docking; Iron–sulfur-binding sites; Isothermal titration calorimetry; Site-directed mutagenesis; Spectral perturbation

PMID:
28975508
DOI:
10.1007/s11120-017-0446-z
[Indexed for MEDLINE]

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