title: Mycobacterium tuberculosis MutT1 (Rv2985) and ADPRase (Rv1700) proteins constitute a two-stage mechanism of 8-oxo-dGTP and 8-oxo-GTP detoxification and adenosine to cytidine mutation avoidance.
abstract: Approximately one third of the world population is infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. A better understanding of the pathogen biology is crucial to develop new tools/strategies to tackle its spread and treatment. In the host macrophages, the pathogen is exposed to reactive oxygen species, known to damage dGTP and GTP to 8-oxo-dGTP and 8-oxo-GTP, respectively. Incorporation of the damaged nucleotides in nucleic acids is detrimental to organisms. MutT proteins, belonging to a class of Nudix hydrolases, hydrolyze 8-oxo-G nucleoside triphosphates/diphosphates to the corresponding nucleoside monophosphates and sanitize the nucleotide pool. Mycobacteria possess several MutT proteins. However, a functional homolog of Escherichia coli MutT has not been identified. Here, we characterized MtuMutT1 and Rv1700 proteins of M. tuberculosis. Unlike other MutT proteins, MtuMutT1 converts 8-oxo-dGTP to 8-oxo-dGDP, and 8-oxo-GTP to 8-oxo-GDP. Rv1700 then converts them to the corresponding nucleoside monophosphates. This observation suggests the presence of a two-stage mechanism of 8-oxo-dGTP/8-oxo-GTP detoxification in mycobacteria. MtuMutT1 converts 8-oxo-dGTP to 8-oxo-dGDP with a Km of ∼50 μM and Vmax of ∼0.9 pmol/min per ng of protein, and Rv1700 converts 8-oxo-dGDP to 8-oxo-dGMP with a Km of ∼9.5 μM and Vmax of ∼0.04 pmol/min per ng of protein. Together, MtuMutT1 and Rv1700 offer maximal rescue to E. coli for its MutT deficiency by decreasing A to C mutations (a hallmark of MutT deficiency). We suggest that the concerted action of MtuMutT1 and Rv1700 plays a crucial role in survival of bacteria against oxidative stress.
authors: Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.
authors: Aravind Goud G
authors: AG
authors: Patil
authors: Pau Biak
authors: PB
authors: Sang
authors: Ashwin
authors: A
authors: Govindan
authors: Umesh
authors: U
authors: Varshney
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000241:Adenosine / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003562:Cytidine / Q000235:genetics / Q000378:metabolism*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D018384:Oxidative Stress / Q000502:physiology*; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D000096964:Nudix Hydrolases
chemical_list: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000241:Adenosine; D001426:Bacterial Proteins; D003562:Cytidine; D003849:Deoxyguanosine; D011755:Pyrophosphatases; D000096964:Nudix Hydrolases