title: How a novel tyrosine-heme cross-link fine-tunes the structure and functions of heme proteins: a direct comparitive study of L29H/F43Y myoglobin.
abstract: 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.
authors.affiliation: School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China. linlinying@hotmail.com ywlin@usc.edu.cn.
authors.forename: Dao-Jing
authors.initials: DJ
authors.lastname: Yan
authors.affiliation: 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.
authors.forename: Hong
authors.initials: H
authors.lastname: Yuan
authors.affiliation: 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.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xiang
authors.affiliation: School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China. linlinying@hotmail.com ywlin@usc.edu.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: He
authors.affiliation: School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China. linlinying@hotmail.com ywlin@usc.edu.cn.
authors.forename: Chang-Ming
authors.initials: CM
authors.lastname: Nie
authors.affiliation: Laboratory of Protein Structure and Function, University of South China, Hengyang 421001, China.
authors.forename: Ge-Bo
authors.initials: GB
authors.lastname: Wen
authors.affiliation: 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.
authors.forename: Ying-Wu
authors.initials: YW
authors.lastname: Lin
authors.affiliation: 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.
authors.forename: Xiangshi
authors.initials: X
authors.lastname: Tan
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D006420:Hemeproteins / Q000737:chemistry*; D008958:Models, Molecular; D009211:Myoglobin / Q000737:chemistry*; D011487:Protein Conformation; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D006420:Hemeproteins; D009211:Myoglobin; D014443:Tyrosine; D006418:Heme