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Chakravarty D, Bihani SC, Banerjee M, Kalwani P, Ballal A. Unique functional insights into the antioxidant response of the cyanobacterial Mn-catalase (KatB). Free Radic Biol Med 2022; 179:266-276. [PMID: 34793931 DOI: 10.1016/j.freeradbiomed.2021.11.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/12/2021] [Indexed: 01/06/2023]
Abstract
KatB, a hexameric Mn-catalase, plays a vital role in overcoming oxidative and salinity stress in the ecologically important, N2-fixing cyanobacterium, Anabaena. The 5 N-terminal residues of KatB, which show a high degree of conservation in cyanobacteria, form an antiparallel β-strand at the subunit interface of the KatB hexamer. In this study, the contribution of these N-terminal non-active site residues, towards the maintenance of the structure, biochemical properties, and redox balance was evaluated. Each N-terminal amino acid residue from the 2nd to the 7th position of KatB was individually mutated to Ala (to express KatBF2A/KatBF3A/KatBH4A/KatBK5E/KatBK6A/KatBE7A) or this entire 6 amino acid stretch was deleted (to yield KatBTrunc). All the above-mentioned KatB variants, along with the wild-type KatB protein (KatBWT), were overproduced in E. coli and purified. In comparison to KatBWT, the KatBF2A/KatBH4A/KatBTrunc proteins were less compact, more prone to chemical/thermal denaturation, and were unexpectedly inactive. KatBF3A/KatBK5E/KatBK6A showed biophysical/biochemical properties that were in between that of KatBWT and KatBF2A/KatBH4A/KatBTrunc. Surprisingly, KatBE7A was more thermostable with higher activity than KatBWT. On exposure to H2O2, E. coli expressing KatBWT/KatBE7A showed considerably reduced formation of ROS and increased survival than the other KatB variants. Utilizing the KatB structure, the molecular basis responsible for the altered stability/activity of the KatB mutants was delineated. This study demonstrates the physiological importance of the N-terminal β-strand of Mn-catalases in combating H2O2 stress and shows that the non-active site residues can be used for rational protein engineering to develop Mn-catalases with improved characteristics.
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Affiliation(s)
- Dhiman Chakravarty
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India
| | - Subhash C Bihani
- Radiation Biology & Health Sciences Division, Trombay, Mumbai, 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India.
| | - Manisha Banerjee
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India
| | - Prakash Kalwani
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India
| | - Anand Ballal
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, India.
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Evaluation of trehalase as an enhancer for a green biocide in the mitigation of Desulfovibrio vulgaris biocorrosion of carbon steel. Bioprocess Biosyst Eng 2022; 45:659-667. [PMID: 34982209 DOI: 10.1007/s00449-021-02684-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 12/20/2021] [Indexed: 02/02/2023]
Abstract
Trehalase can biocatalyze the conversion of trehalose to glucose. It is an enzyme that plays an important role in biofilm formation. Thus, trehalase has been patented as a chemical for preventing and treating biofilms. Sulfate-reducing bacteria (SRB) biofilms are often found responsible for biocorrosion, also known as microbiologically infuenced corrosion (MIC), especially in the oil and gas industries and in water utilities. The MIC treatment process typically requires biocide treatment of biofilms, sometimes together with scrubbing. Owing to environmental concerns, a lower biocide dosage is desired in the treatment process. In this work, trehalase was tested as a green biocide enhancer to enhance tetrakis hydroxymethyl phosphonium sulfate (THPS) in the prevention of Desulfovibrio vulgaris MIC of C1018 carbon steel in ATCC 1249 culture medium at 37 °C. THPS is one of the most popular industrial biocides owing to its broad-spectrum efficacy and green chemical status. After 7 days of incubation in 50 mL anaerobic vials containing 40 mL culture medium at pH 7.0, the sessile cell counts indicated that 50 ppm (w/w) THPS + 30 ppm (w/w) trehalase led to an extra 5.7-fold sessile cell reduction when compared with the 50 ppm THPS alone treatment. As a consequence, the combination treatment also resulted in an extra 54% in pit depth reduction and 30% in weight loss reduction when compared with the 50 ppm THPS alone treatment (with 9.0 μm and 1.0 mg/cm2). The biofilm images corroborated the decreased sessile cell count and pitting corrosion.
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