3e4w

Publication Abstract from PubMed

True catalases are tyrosine-liganded, usually tetrameric, hemoproteins with subunit sizes of approximately 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 A 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 ( approximately 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.

The structure and peroxidase activity of a 33-kDa catalase-related protein from Mycobacterium avium ssp. paratuberculosis.,Pakhomova S, Gao B, Boeglin WE, Brash AR, Newcomer ME Protein Sci. 2009 Dec;18(12):2559-68. PMID:19827095^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.