Premium
The structure and peroxidase activity of a 33‐kDa catalase‐related protein from Mycobacterium avium ssp. paratuberculosis
Author(s) -
Pakhomova Svetlana,
Gao Benlian,
Boeglin William E.,
Brash Alan R.,
Newcomer Marcia E.
Publication year - 2009
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.265
Subject(s) - peroxidase , catalase , chemistry , heme , biochemistry , hemeprotein , oxidoreductase , paratuberculosis , protein subunit , peroxide , hydrogen peroxide , enzyme , protein structure , stereochemistry , mycobacterium , biology , bacteria , gene , organic chemistry , genetics
Abstract True catalases are tyrosine‐liganded, usually tetrameric, hemoproteins with subunit sizes of ∼55–84 kDa. Recently characterized hemoproteins with a catalase‐related structure, yet lacking in catalatic activity, include the 40–43 kDa allene oxide synthases of marine invertebrates and cyanobacteria. Herein, we describe the 1.8 Å X‐ray crystal structure of a 33 kDa subunit hemoprotein from Mycobacterium avium ssp. paratuberculosis (annotated as MAP‐2744c) , that retains the core elements of the catalase fold and exhibits an organic peroxide‐dependent peroxidase activity. MAP‐2744c exhibits negligible catalatic activity, weak peroxidatic activity using hydrogen peroxide (20/s) and strong peroxidase activity (∼300/s) using organic hydroperoxides as co‐substrate. Key amino acid differences significantly impact prosthetic group conformation and placement and confer a distinct activity to this prototypical member of a group of conserved bacterial “minicatalases”. Its structural features and the result of the enzyme assays support a role for MAP‐2744c and its close homologues in mitigating challenge by a variety of reactive oxygen species.