Expression of a bacterial catalase in a strictly anaerobic methanogen significantly increases tolerance to hydrogen peroxide but not oxygen

Abstract

Haem-dependent catalase is an antioxidant enzyme that degrades H2O2, producing H2O and O2, and is common in aerobes. Catalase is present in some strictly anaerobic methane-producing archaea (methanogens), but the importance of catalase to the antioxidant system of methanogens is poorly understood. We report here that a survey of the sequenced genomes of methanogens revealed that the majority of species lack genes encoding catalase. Moreover, Methanosarcina acetivorans is a methanogen capable of synthesizing haem and encodes haem-dependent catalase in its genome; yet, Methanosarcina acetivorans cells lack detectable catalase activity. However, inducible expression of the haem-dependent catalase from Escherichia coli (EcKatG) in the chromosome of Methanosarcina acetivorans resulted in a 100-fold increase in the endogenous catalase activity compared with uninduced cells. The increased catalase activity conferred a 10-fold increase in the resistance of EcKatG-induced cells to H2O2 compared with uninduced cells. The EcKatG-induced cells were also able to grow when exposed to levels of H2O2 that inhibited or killed uninduced cells. However, despite the significant increase in catalase activity, growth studies revealed that EcKatG-induced cells did not exhibit increased tolerance to O2 compared with uninduced cells. These results support the lack of catalase in the majority of methanogens, since methanogens are more likely to encounter O2 rather than high concentrations of H2O2 in the natural environment. Catalase appears to be a minor component of the antioxidant system in methanogens, even those that are aerotolerant, including Methanosarcina acetivorans. Importantly, the experimental approach used here demonstrated the feasibility of engineering beneficial traits, such as H2O2 tolerance, in methanogens.

Pathways of Iron and Sulfur Acquisition, Cofactor Assembly, Destination, and Storage in Diverse Archaeal Methanogens and Alkanotrophs

“…We next searched for examples of heme b -dependent proteins shown in a widescale study of diverse bacterial genomes to be broadly distributed in aerotolerant anaerobes ( 88 ), since these might also be prevalent in aerotolerant archaeal methanogens, methanotrophs, and alkanotrophs. KatG is a heme b -dependent catalase-peroxidase that is known to be critical for H 2 O 2 detoxification in aerobes ( 89 ) and has been identified in multiple anaerobes (including Methanosarcina acetivorans ) ( 90 ). Cytochrome bd oxidase (Cyt bd ) is a terminal respiratory oxidase with high affinity for extremely low quantities of O 2 in the obligate anaerobic bacteria Bacteroides fragilis and Desulfovibrio gigas ( 91 , 92 ).…”

The Methanosarcina acetivorans thioredoxin system activates DNA binding of the redox-sensitive transcriptional regulator MsvR

“…The activation of MaMsvR DNA binding by MaTrx7 also integrates P msvR regulation by MsvR into the physiology of M. acetivorans , which supports the future use of P msvR in engineering oxidant-responsive gene expression strains. For example, we have previously demonstrated that increased expression of catalase protects M. acetivorans from H 2 O 2 [16]. …”

Targeted and contextual redescription set exploration

“…The correlation between these two attributes is statistically significant (metabolism PAH degrading, C OG 1592 , 0.72, < 2.2 • 10 −16 ). The usage of rubrerythrin in anaerob bacteria has been confirmed (Jenney et al 1999;Lumppio et al 2001;Jennings et al 2014) in the process of degrading O − 2 and H 2 O 2 without producing O 2 . The attribute (hyperthermophil, archaeal, hydrotherm, vent, heterotroph), is significantly associated (co-occurring in 37 redescriptions) and correlated with attribute C OG 3351 (putative archaeal flagellar protein D/E), ((hyperthermophil, archaeal, hydrotherm, vent, heterotroph), C OG 3351 , 0.49, < 2.2 • 10 −16 ).…”