Molecular and biochemical characterization of All0580 as a methylglyoxal detoxifying glyoxalase II of Anabaena sp. PCC7120 that confers abiotic stress tolerance in E. coli

Abiotic stresses enhance cellular reactive oxygen species (ROS) level which results in toxic methylglyoxal (MG) production. Glyoxalases catalyze the conversion of toxic MG into non-toxic lactic acid whose properties and function are still unknown in cyanobacteria. This is the first attempt to characterize All0580 from Anabaena sp. PCC7120 as GlyII using in silico and wet lab approaches. Data of functional complementation of E. coli GlyII mutant (ΔgloB), enzyme kinetics and ESI-MS analysis suggested that All0580 harbors distinctive GlyII activity. The catalytic efficiency of All0580 (3 × 10⁶ M^-1 s^-1) is higher than Arabidopsis GlyII. AAS analysis revealed the presence of a binuclear Zn/Fe centre in All0580 active site. The qRT-PCR of the target gene revealed maximum up-regulation in salinity followed by drought, arsenic, heat, and UV-B stresses. BL21/pET-21a-all0580 showed 1.5 to 10 fold increased growth and up to 4 fold decreased intracellular MG level as compared to BL21/pET-21a cells under various abiotic stresses and MG. A 39% drop in ROS generation by BL21/pET-21a-all0580 under MG stress suggested its potential to manage MG toxicity. Above attributes suggest that the hypothetical protein All0580 is a novel GlyII of cyanobacteria which heterologously confers tolerance to multiple abiotic stresses in E. coli.