title: Structural insight into unique properties of protoporphyrinogen oxidase from Bacillus subtilis.
abstract: Protoporphyrinogen IX oxidase (PPO) converts protoporphyrinogen IX to protoporphyrin IX, playing an important part in the heme/chlorophyll biosynthetic pathway. Bacillus subtilis PPO (bsPPO) is unique among PPO family members in that it is a soluble monomer, is inefficiently inhibited by the herbicide acifluorfen (AF) and has broader substrate specificity than other PPO enzymes. Here, we present the crystal structure of bsPPO bound to AF. Our structure shows that the AF molecule binds to a new site outside the previously identified inhibitor binding pocket. Most importantly, the benzene ring of the 2-nitrobenzoic acid moiety of AF lies parallel to the isoalloxazine ring of FAD at a distance of less than 3.5A, providing a framework for the interaction of FAD with the substrate protoporphyrinogen IX. Furthermore, our structure reveals that the larger substrate binding chamber and predominantly positively charged chamber surface of bsPPO are more favorable for the binding of coproporphyrinogen-III. These crystallographic findings uncover biochemically unique properties of bsPPO, providing important information for further understanding the enzymatic mechanism.
authors: Tianjin Key Laboratory of Protein Science, College of Life Science, Nankai University, Tianjin 300071, China.
authors: Xiaohong
authors: X
authors: Qin
authors: Lu
authors: L
authors: Sun
authors: Xin
authors: X
authors: Wen
authors: Xue
authors: X
authors: Yang
authors: Ying
authors: Y
authors: Tan
authors: Hao
authors: H
authors: Jin
authors: Qiongyao
authors: Q
authors: Cao
authors: Weihong
authors: W
authors: Zhou
authors: Zhen
authors: Z
authors: Xi
authors: Yuequan
authors: Y
authors: Shen
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D003460:Crystallization; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D016296:Mutagenesis; D009579:Nitrobenzoates / Q000378:metabolism; D011485:Protein Binding; D050768:Protoporphyrinogen Oxidase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D009579:Nitrobenzoates; D050768:Protoporphyrinogen Oxidase; C018425:acifluorfen