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J Genet ; 2020 Sep; 99: 1-11
Article | IMSEAR | ID: sea-215489


Genome sequence of Acinetobacter baumannii DS002 revealed the existence of seven contigs with features of indigenous plasmids. Of the seven contigs, three of them have shown size and sequence identity. They appeared to have been generated due to the unique recombination events leading to a large-scale recombination and sequence inversions. The rest of the indigenous plasmids have shown significant size variations and contained the genetic repertoire required for the detoxification of formaldehyde and biosynthesis of exopolysaccharides. Genetic modules encoding novel toxin–antitoxin systems were found in most of the plasmids to ensure their survival in the host. In some instances, the toxin and antitoxin coding sequences were found on two different plasmids promoting the cosegregation of these two plasmids into the daughter cells

J Genet ; 2019 Feb; 98: 1-10
Article | IMSEAR | ID: sea-215476


Genes encoding structurally independent phosphotriesterases (PTEs) are identified in soil bacteria. These pte genes, often identified on mobilizable and self-transmissible plasmids are organized as mobile genetic elements. Their dissemination through lateral gene transfer is evident due to the detection of identical organophosphate degradation genes among soil bacteria with little orno taxonomic relationship. Convergent evolution of PTEs provided selective advantages to the bacterial strain as they convert toxic phosphotriesters (PTs) into a source of phosphate. The residues of organophosphate (OP) compounds that accumulate in a soil are proposed to contribute to the evolution of PTEs through substrate-assisted gain-of-function. This review provides comprehensiveinformation on lateral transfer of pte genes and critically examines proposed hypotheses on their evolution in the light of the short half-life of OPs in the environment. The review also proposes alternate factors that have possibly contributed to the evolution and lateral mobility of PTEs by taking into account their biology and analyses of pte genes in genomic and metagenomic databases.

Indian J Biochem Biophys ; 2011 Feb; 48(1): 29-34
Article in English | IMSEAR | ID: sea-135297


Bacterial organophosphate hydrolases (OPH) have been shown to hydrolyze structurally diverse group of organophosphate (OP) compounds and nerve agents. Due to broad substrate range and unusual catalytic properties, the OPH has successfully been used to develop eco-friendly strategies for detection and decontamination of OP compounds. However, their usage has failed to gain necessary acceptance, due to short half-life of the enzyme and loss of activity during process development. In the present study, we report a simple procedure for immobilization of OPH on biocompatible gelatin pads. The covalent coupling of OPH using glutaraldehyde spacer has been found to dramatically improve the enzyme stability. There is no apparent loss of OPH activity in OPH-gelatin pads stored at room temperature for more than six months. As revealed by a number of kinetic parameters, the catalytic properties of immobilized enzyme are found to be comparable to the free enzyme. Further, the OPH‑gelatin pads effectively eliminate OP insecticide methyl parathion and nerve agent sarin.

Enzyme Stability , Enzymes, Immobilized/chemistry , Escherichia coli/enzymology , Escherichia coli/genetics , Gelatin/chemistry , Hydrolysis , Insecticides/poisoning , Methyl Parathion/chemistry , Organophosphorus Compounds/chemistry , Phosphoric Monoester Hydrolases/genetics , Phosphoric Monoester Hydrolases/isolation & purification , Phosphoric Monoester Hydrolases/metabolism , Sarin/chemistry , Substrate Specificity