How a novel tyrosine-heme cross-link fine-tunes the structure and functions of heme proteins: a direct comparitive study of L29H/F43Y myoglobin

A heme-protein cross-link is a key post-translational modification (PTM) of heme proteins. Meanwhile, the structural and functional consequences of heme-protein cross-links are not fully understood, due to limited studies on a direct comparison of the same protein with and without the cross-link. A...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2015-01, Vol.44 (43), p.18815-18822
Main Authors: Yan, Dao-Jing, Yuan, Hong, Li, Wei, Xiang, Yu, He, Bo, Nie, Chang-Ming, Wen, Ge-Bo, Lin, Ying-Wu, Tan, Xiangshi
Format: Article
Language:English
Subjects:
Binding
Cross-Linking Reagents - chemistry
Crosslinking
Formations
Heme - chemistry
Hemeproteins - chemistry
Hydroxyl groups
Models, Molecular
Myoglobin
Myoglobin - chemistry
Networks
Protein Conformation
Proteins
Spectroscopy
Tyrosine - chemistry
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Summary:A heme-protein cross-link is a key post-translational modification (PTM) of heme proteins. Meanwhile, the structural and functional consequences of heme-protein cross-links are not fully understood, due to limited studies on a direct comparison of the same protein with and without the cross-link. A Tyr-heme cross-link with a C-O bond is a newly discovered PTM of heme proteins, and is spontaneously formed in F43Y myoglobin (Mb) between the Tyr hydroxyl group and the heme 4-vinyl group in vivo. In this study, we found that with an additional distal His29 introduced in the heme pocket, the double mutant L29H/F43Y Mb can form two distinct forms under different protein purification conditions, with and without a novel Tyr-heme cross-link. By solving the X-ray structures of both forms of L29H/F43Y Mb and performing spectroscopic studies, we made a direct structural and functional comparison in the same protein scaffold. It revealed that the Tyr-heme cross-link regulates the heme distal hydrogen-bonding network, and fine-tunes not only the spectroscopic and ligand binding properties, but also the protein reactivity. Moreover, the formation of the Tyr-heme cross-link in the double mutant L29H/F43Y Mb was investigated in vitro. This study addressed the key issue of how Tyr-heme cross-link fine-tunes the structure and functions of the heme protein, and provided a plausible mechanism for the formation of the newly discovered Tyr-heme cross-link.
ISSN:1477-9226
1477-9234
DOI:10.1039/c5dt03040d