A cold‐active esterase enhances mesophilic properties through Mn²⁺ binding

Abstract

A key aspect of adaptation to cold environments is the production of cold‐active enzymes by psychrophilic organisms. These enzymes not only have high activity at low temperatures, but also exhibit remarkable structural flexibility and thermolability. In this context, the role of metal ions has been little explored, and the few available studies seem to suggest that metal binding counteracts structural flexibility. This article reports an investigation into the role of the binding of manganese ion (Mn2+) in the thermal adaptation of an esterase (M‐Est) of the GDSx family, identified in the genome of the Antarctic bacterium Marinomonas sp. ef1. M‐Est is specific for esters containing acetate groups and turned out to be a highly thermolabile cold‐active enzyme, with a catalysis optimum temperature of 5 °C and a melting temperature of 31.7 °C. A combination of biochemical and computational analyses, including molecular dynamics simulations, revealed that M‐Est binds Mn2+ ions via a single binding site located on the surface of the enzyme, close to the active site. Although the interaction between M‐Est and Mn2+ induces only local conformational changes involving the active site, quite surprisingly they trigger an improvement in both thermal stability and catalytic efficiency under mild temperature conditions. These results, together with the conservation of the Mn2+ binding site among psychrophilic and psychrotolerant homologues, suggest that Mn2+ binding may be a useful, albeit atypical, strategy to mitigate the detrimental effects of temperature on true cold‐active enzymes.

Cold-Active Lipases and Esterases: A Review on Recombinant Overexpression and Other Essential Issues

“…The di-Mn 2+ ions maintained the ‘loose’ structure responsible for keeping the enzyme active site flexible and further enhanced its performance at low temperatures [ 143 ]. Another role of Manganese Mn 2+ on the low-temperature adaption of a cold-active esterase was recently described by Marchetti, Orlando [ 144 ]; as with other psychrotolerant and psychrophilic homologues, the Mn 2+ binding site was discovered on the surface of the enzyme close to the active region and the esterase’s interaction with the Mn 2+ ion only results in a local conformational shift near its active site, which unexpectedly improves both its catalytic efficiency and thermal stability [ 144 ].…”

Unravelling the complexity of enzyme catalysis

“…Using crystallographic and biochemical assays, Ippei Watanabe and colleagues evaluate in detail the consequences of 4,6-O-disulfated disaccharide moieties in chondroitin sulfate E on the activity of chondrointinase ABC1 activity [15]. Damping-down dynamics can also be important, as shown by Alessandro Marchetti et al [16]. They show that the binding of manganese ions on the surface of the enzyme, close to the active site, is likely responsible for the adaptation of a cold-active esterase from the Antarctic bacterium Marinomonas sp.…”

“…Damping‐down dynamics can also be important, as shown by Alessandro Marchetti et al . [16]. They show that the binding of manganese ions on the surface of the enzyme, close to the active site, is likely responsible for the adaptation of a cold‐active esterase from the Antarctic bacterium Marinomonas sp.…”