Novel molecular insights into the anti‐oxidative stress response and structure–function of a salt‐inducible cyanobacterial Mn‐catalase

Abstract

KatB, a salt-inducible Mn-catalase, protects the cyanobacterium Anabaena from salinity/oxidative stress. In this report, we provide distinctive insights into the biological-biochemical function of KatB at the molecular level. Anabaena overexpressing the wild-type KatB protein (KatBWT) detoxified H 2 O 2 efficiently, showing reduced burden of reactive oxygen species compared with the strain overproducing KatBF2V (wherein F-2 is replaced by V). Correspondingly, the KatBWT protein also displayed several folds more activity than KatBF2V. Interestingly, the KatB variants with large hydrophobic amino acids (F/W/Y) were more compact, showed enhanced activity, and were resistant to thermal/chemical denaturation than variants with smaller residues (G/A/V) at the second position. X-ray crystallography-based analysis showed that F-2 was required for appropriate interactions between two subunits.These contacts provided stability to the hexamer, making it more compact. F-2, through its interaction with F-66 and W-43, formed the proper hydrophobic pocket that held the active site together. Consequently, only residues that supported activity (i.e., F/Y/W) were selected at the second position in Mn-catalases during evolution.This study (a) demonstrates that modification of nonactive site residues can alter the response of catalases to environmental stress and (b) has expanded the scope of amino acids that can be targeted for rational protein engineering in plants.

Nuclear transport factor GmNTF2B‐1 enhances soybean drought tolerance by interacting with oxidoreductase GmOXR17 to reduce reactive oxygen species content

“…The catalase activity assay was conducted (Figure S13), with a spectrophotometer, by quantifying H 2 O 2 decomposition as reported previously (Chakravarty et al. , 2019). The GmOXR17 transgenic roots were obtained by K599 Agrobacterium infection.…”

Amino Acid Interactions (INTAA) web server v2.0: a single service for computation of energetics and conservation in biomolecular 3D structures

“…The INTAA web server has been used recently, for example, for the investigation of effective pairwise potentials between amino acid residues in proteins ( 7 ), for the comparison of the strength of interactions of particular amino acid residues ( 8 ), or as a reference method for the calculation of IEs ( 9 ). The INTAA web server has been further employed in the design of peptidic cysteine protease inhibitors targeted against the malaria parasite ( 10 ), for the elucidation of the structure–function relationship in a cyanobacterial Mn-catalase enzyme ( 11 ), and for the investigation of a missense mutation in a human UDP-glucose dehydrogenase linked with developmental delay ( 12 ).…”

Occurrence of a single-species cyanobacterial bloom in a lake in Cyprus: monitoring and treatment with hydrogen peroxide-releasing granules

“…The hydroxyl radicals ( . OH) formed by the oxidant inhibit the electron transport of photosystem II (PSII), causing reduction of its photosynthetic activity and leading to cellular death [17,18]. The efficiency of such treatment varies and depends on the nutrient load of the matrix, the species composition and abundance, the bloom density, and light intensity.…”