Open AccessThe Arabidopsis locus AT3G03890 encodes a dimeric β-barrel protein implicated in heme degradation
Author(s) -
Jia Wang,
Qi Guo,
Xiaoyi Li,
Xiao Wang,
Lin Liu
Publication year - 2020
Publication title -
biochemical journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 265
eISSN - 1470-8728
pISSN - 0264-6021
DOI - 10.1042/bcj20200712
Subject(s) - tetrapyrrole , heme , biliverdin , biochemistry , arabidopsis , heme oxygenase , biology , chemistry , mutant , gene , enzyme
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.