Plant tetrapyrroles, including heme and bilins, are synthesized in plastids. Heme oxygenase (HO) catalyzes the oxidative cleavage of heme to the linear tetrapyrrole biliverdin as the initial step in bilin biosynthesis. Besides the canonical α-helical HO that is conserved from prokaryotes to human, a subfamily of non-canonical dimeric β-barrel HO has been found in bacteria. In this work, we discovered that the Arabidopsis locus AT3G03890 encodes a dimeric β-barrel protein that is structurally related to the putative non-canonical HO and is located in chloroplasts. The recombinant protein was able to bind and degrade heme in a manner different from known HO proteins. Crystal structure of the heme–protein complex reveals that the heme-binding site is in the interdimer interface and the heme iron is co-ordinated by a fixed water molecule. Our results identify a new protein that may function additionally in the tetrapyrrole biosynthetic pathway.
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December 2020
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The cover image shows the ternary complex structure of pol? incorporating dCTP* opposite templating xanthine. In this issue Jung and colleagues (pp. 4797–4810) demonstrate the solved structure of human DNA polymerase η (ploη) catalyzing across xanthine and hypoxanthine. Image courtesy of Seongmin Lee.
Research Article|
December 24 2020
The Arabidopsis locus AT3G03890 encodes a dimeric β-barrel protein implicated in heme degradation
Jia Wang;
Jia Wang
Conceptualization, Investigation, Writing - original draft, Writing - review & editing
1Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Haidian, Beijing 100093, China
2Graduate School, University of Chinese Academy of Sciences, Shijingshan, Beijing 100049, China
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Qi Guo;
Qi Guo
Investigation, Writing - original draft
1Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Haidian, Beijing 100093, China
2Graduate School, University of Chinese Academy of Sciences, Shijingshan, Beijing 100049, China
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Xiaoyi Li;
Xiaoyi Li
Funding acquisition, Investigation, Writing - original draft
1Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Haidian, Beijing 100093, China
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Xiao Wang;
Xiao Wang
Validation, Investigation, Writing - original draft
3School of Life Sciences, Anhui University, Hefei, Anhui 230601, China
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Lin Liu
Conceptualization, Resources, Supervision, Writing - original draft, Writing - review & editing
3School of Life Sciences, Anhui University, Hefei, Anhui 230601, China
Correspondence: Lin Liu (liulin@ahu.edu.cn)
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Publisher: Portland Press Ltd
Received:
September 07 2020
Revision Received:
December 03 2020
Accepted:
December 04 2020
Accepted Manuscript online:
December 07 2020
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2020 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society
2020
Biochem J (2020) 477 (24): 4785–4796.
Article history
Received:
September 07 2020
Revision Received:
December 03 2020
Accepted:
December 04 2020
Accepted Manuscript online:
December 07 2020
Citation
Jia Wang, Qi Guo, Xiaoyi Li, Xiao Wang, Lin Liu; The Arabidopsis locus AT3G03890 encodes a dimeric β-barrel protein implicated in heme degradation. Biochem J 23 December 2020; 477 (24): 4785–4796. doi: https://doi.org/10.1042/BCJ20200712
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