title: A Salt-Inducible Mn-Catalase (KatB) Protects Cyanobacterium from Oxidative Stress.
abstract: Catalases, enzymes that detoxify H2O2, are widely distributed in all phyla, including cyanobacteria. Unlike the heme-containing catalases, the physiological roles of Mn-catalases remain inadequately characterized. In the cyanobacterium Anabaena, pretreatment of cells with NaCl resulted in unusually enhanced tolerance to oxidative stress. On exposure to H2O2, the NaCl-treated Anabaena showed reduced formation of reactive oxygen species, peroxides, and oxidized proteins than the control cells (i.e. not treated with NaCl) exposed to H2O2. This protective effect correlated well with the substantial increase in production of KatB, a Mn-catalase. Addition of NaCl did not safeguard the katB mutant from H2O2, suggesting that KatB was indeed responsible for detoxifying the externally added H2O2. Moreover, Anabaena deficient in KatB was susceptible to oxidative effects of salinity stress. The katB gene was strongly induced in response to osmotic stress or desiccation. Promoter-gfp analysis showed katB to be expressed only in the vegetative cells but not in heterocysts. Biochemically, KatB was an efficient, robust catalase that remained active in the presence of high concentrations of NaCl. Our findings unravel the role of Mn-catalase in acclimatization to salt/oxidative stress and demonstrate that the oxidative stress resistance of an organism can be enhanced by a simple compound such as NaCl.
authors.affiliation: Molecular Biology Division (D.C., M.B., A.B.) and Solid State Physics Division (S.C.B.), Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; andHomi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India (D.C., A.B.).
authors.forename: Dhiman
authors.identifier: http://orcid.org/0000-0002-3186-785X
authors.initials: D
authors.lastname: Chakravarty
authors.affiliation: Molecular Biology Division (D.C., M.B., A.B.) and Solid State Physics Division (S.C.B.), Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; andHomi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India (D.C., A.B.).
authors.forename: Manisha
authors.identifier: http://orcid.org/0000-0002-3605-7741
authors.initials: M
authors.lastname: Banerjee
authors.affiliation: Molecular Biology Division (D.C., M.B., A.B.) and Solid State Physics Division (S.C.B.), Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; andHomi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India (D.C., A.B.).
authors.forename: Subhash C
authors.identifier: http://orcid.org/0000-0002-0724-4919
authors.initials: SC
authors.lastname: Bihani
authors.affiliation: Molecular Biology Division (D.C., M.B., A.B.) and Solid State Physics Division (S.C.B.), Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India; andHomi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India (D.C., A.B.) aballal@barc.gov.in.
authors.forename: Anand
authors.identifier: http://orcid.org/0000-0002-8776-3021
authors.initials: A
authors.lastname: Ballal
mesh_terms: D017033:Anabaena / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D017382:Reactive Oxygen Species; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D002374:Catalase