Catalase bacterial gene

For the experiments biofilm from separately grown Sp and Aa strains was made on polycarbonate membrane. First the Sp biofilm was spread on the membrane and after a spot of the Aa culture was added. In this way a 25 pm diameter bacterial biofilm of Sg with a spot of 5-7 pm Aa in the middle was obtained as substrate for SECM studies. Two different strains of Aa were used - the Y4 and the Y4-katA -containing an insertion mutant of the catalase-encoding gene katA. It is Aa with higher tolerance to hydrogen peroxide toxicity. 

The effectors of the mammalian host immune attack against filaria include reactive oxygen intermediates. Filarial nematodes express glutathione peroxidase, thioredoxin peroxidase and superoxide dismutase at their surface - enzymes believed to protect the nematode from this attack (Selkirk et al., 1998). A bacterial catalase gene has been identified that most probably derives from the endosymbiont genome (Henkle-Duhrsen et al., 1998) this enzyme may contribute with other enzymes to the protection of both Wolbachia and its nematode host from oxygen radicals. 

Isoniazid (INH) is a synthetic derivative of isonico-tinic acid. It has bactericidal activity against both intra- and extra-cellular mycobacteria. It also displays anti-bacterial activity in caseous lesions, but only in proliferating cells. Losing genes which code for catalase and peroxidase is the major mechanism through which resistance occurs. Single mutations can rapidly result in such resistance if isoniazid is used alone. Its mechanism of action is presumably based on inhibition of the synthesis of mycolic acids, unique and essential components of the mycobacterial cell wall. 

Welinder KG (1991) Bacterial catalase-peroxidases are gene duplicated members of the plant peroxidase superfamily. Biochim Biophys Acta 1080 215-220... 

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