Recognition and Discrimination of Gases by the Oxygen-sensing Signal Transducer Protein Hemat As Revealed by Ftir Spectroscopy.
From: Department of Chemistry, University of Crete, 71409 Heraklion, Crete, Greece.
Biochemistry
- Publish Date: Jun 2006
- ISSN: 0006-2960
- Volume: 45
- Issue: 25
- Pages: 7763-6
- Medium: Print
- Language: English
- Citation (JAMA): Pinakoulaki Eftychia, Yoshimura Hideaki, Yoshioka Shiro, et al. Recognition and Discrimination of Gases by the Oxygen-sensing Signal Transducer Protein Hemat As Revealed by Ftir Spectroscopy.. Biochemistry Jun 2006;45:7763-6
Abstract
The determination of ligand binding properties is a key step in our understanding of gas sensing and discrimination by gas sensory proteins. HemAT is a newly discovered signal transducer heme protein that recognizes O(2) and discriminates against other gases such as CO and NO. We have used FTIR spectroscopy on CO- and NO-bound sensor domain HemAT and sensor domain distal mutants Y70F, T95A, R91A, and L92A to gain insight into the structure of the iron-bound ligand at ambient temperature. These mutations were designed to perturb the electrostatic field near the iron-bound gaseous ligand and also allow us to investigate the communication pathway between the distal residues of the protein and the heme. We show the formation of both H-bonded and non-H-bonded conformations in the CO-bound forms. In addition, we report the presence of multiple conformations in the NO-bound forms. Such distal H-bonding is crucial for ligand binding and activation by the heme. The comparison of the O(2), NO, and CO data demonstrates that Thr95 and Tyr70 are crucial for ligand recognition and discrimination and, thus, for specific sensing of gases, and L92 is crucial for controlling the conformational changes of the Thr95 and Tyr70 residues upon NO binding.
Mesh Headings (Keywords): Amino Acid Sequence, Bacterial Proteins, Binding Sites, Carbon Monoxide, Hemeproteins, Hydrogen Bonding, Nitric Oxide, Oxygen, Protein Conformation, Signal Transduction, Spectroscopy, Fourier Transform Infrared
Check for Full Text / PubMed Unique Identifier (PMID): 16784227
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