Anabaena sp. DyP-type peroxidase is a tetramer consisting of two asymmetric dimers.
Yoshida, T., Ogola, H.J., Amano, Y., Hisabori, T., Ashida, H., Sawa, Y., Tsuge, H., Sugano, Y.(2016) Proteins 84: 31-42
- PubMed: 26492416 
- DOI: https://doi.org/10.1002/prot.24952
- Primary Citation of Related Structures:  
5C2I - PubMed Abstract: 
DyP-type peroxidases are a newly discovered family of heme peroxidases distributed from prokaryotes to eukaryotes. Recently, using a structure-based sequence alignment, we proposed the new classes, P, I and V, as substitutes for classes A, B, C, and D [Arch Biochem Biophys 2015;574:49-55]. Although many class V enzymes from eukaryotes have been characterized, only two from prokaryotes have been reported. Here, we show the crystal structure of one of these two enzymes, Anabaena sp. DyP-type peroxidase (AnaPX). AnaPX is tetramer formed from Cys224-Cys224 disulfide-linked dimers. The tetramer of wild-type AnaPX was stable at all salt concentrations tested. In contrast, the C224A mutant showed salt concentration-dependent oligomeric states: in 600 mM NaCl, it maintained a tetrameric structure, whereas in the absence of salt, it dissociated into monomers, leading to a reduction in thermostability. Although the tetramer exhibits non-crystallographic, 2-fold symmetry in the asymmetric unit, two subunits forming the Cys224-Cys224 disulfide-linked dimer are related by 165° rotation. This asymmetry creates an opening to cavities facing the inside of the tetramer, providing a pathway for hydrogen peroxide access. Finally, a phylogenetic analysis using structure-based sequence alignments showed that class V enzymes from prokaryotes, including AnaPX, are phylogenetically closely related to class V enzymes from eukaryotes.
Organizational Affiliation: 
Department of Bioresource and Environmental Sciences, Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, 603-8555, Japan.