Structure of lpg0406, a carboxymuconolactone decarboxylase family protein possibly involved in antioxidative response from Legionella pneumophila

Abstract

Lpg0406, a hypothetical protein from Legionella pneumophila, belongs to carboxymuconolactone decarboxylase (CMD) family. We determined the crystal structure of lpg0406 both in its apo and reduced form. The structures reveal that lpg0406 forms a hexamer and have disulfide exchange properties. The protein has an all-helical fold with a conserved thioredoxin-like active site CXXC motif and a proton relay system similar to that of alkylhydroperoxidase from Mycobacterium tuberculosis (MtAhpD), suggesting that lpg0406 might function as an enzyme with peroxidase activity and involved in antioxidant defense. A comparison of the size and the surface topology of the putative substrate-binding region between lpg0406 and MtAhpD indicates that the two enzymes accommodate the different substrate preferences. The structural findings will enhance understanding of the CMD family protein structure and its various functions.

γ-Carboxymuconolactone decarboxylase: a novel cell cycle-related basal body protein in the early branching eukaryote Trichomonas vaginalis

“…Gene Ontology (GO) predicted that TvCMD1 functions in electron transport, namely, it has peroxiredoxin activity [ 48 ]. Furthermore, non-canonical CMD has been demonstrated to have disulfide reductase or thioredoxin activities [ 31 , 32 ]. The putative cysteine residues were not found in the protein sequence, suggesting that neither electron transfer nor iron-sulfur cluster docking was employed by TvCMD1.…”

“…Previous studies demonstrated that non-canonical CMDs serve as disulfide reductase- and thioredoxin-like proteins [ 31 , 32 ]. To examine the probable function of TvCMD1, we divided the TvCMD1 sequence into two CMD signatures and aligned them with these CMDs.…”

Formaldehyde Stress Responses in Bacterial Pathogens

“…These are adhA, yraC , and yraA , which encode for an AdhC homolog, a γ-carboxymuconolactone decarboxylase, and a cysteine proteinase, respectively ( Huyen et al, 2009 ). YraC is proposed to be a component of protocateculate metabolism and a homolog of YraC from Legionella pneumophila has been shown to display peroxidase activity ( Huyen et al, 2009 ; Chen et al, 2015 ). How YraC contributes to the defense against formaldehyde toxicity remains to be defined.…”

Lignin induced iron reduction by novel sp., Tolumonas lignolytic BRL6-1

“…This subset of proteins included the protein with the highest abundance listed in lignin-amended conditions in both phases, which was annotated as a carboxymuconolactone decarboxylase (CMD) family protein (Pfam 02627). The CMD family of proteins is associated with aromatic degradation in aerobic bacteria, via the protocatechuate branch of the β-ketoadipate pathway, as well as antioxidant defense via peroxidase activity [42,43]. The CMD family protein identified in BRL6-1 contained an alkylhydroperoxidase (AhpD) domain and CXXC motif (log 2 fold-change of 8 and 7, respectively) (Fig 2A).…”

“…The CMD family protein identified in BRL6-1 contained an alkylhydroperoxidase (AhpD) domain and CXXC motif (log 2 fold-change of 8 and 7, respectively) (Fig 2A). Based on the CXXC motif, it is thought that the protein detected in BRL6-1 has AhpD-like activity [42]. AhpD is part of an antioxidant defense system that forms a complex with peroxiredoxin, AhpC.…”