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 th ...
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.
Organizational Affiliation:
Department of Chemistry, Tsinghua University, Beijing 100084, China.,Department of Chemistry/Shanghai Key Lab of Chemical Biology for Protein Research & Institute of Biomedical Science, Fudan University, Shanghai 200433, China. xstan@fudan.edu.cn.,School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China. linlinying@hotmail.com ywlin@usc.edu.cn and Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China.,Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China.,School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China. linlinying@hotmail.com ywlin@usc.edu.cn.
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