A cold-active esterase enhances mesophilic properties through Mn²⁺ binding.

Area of Science:

• Biochemistry
• Structural Biology
• Enzymology

Background:

• Psychrophilic organisms produce cold-active enzymes crucial for adaptation to cold environments.
• These enzymes possess high activity at low temperatures but are structurally flexible and thermolabile.
• The role of metal ions in modulating enzyme flexibility and stability is poorly understood.

Purpose of the Study:

• To investigate the role of manganese ion (Mn2+) binding in the thermal adaptation of a cold-active esterase (M-Est) from Marinomonas sp. ef1.
• To understand how Mn2+ affects the structural flexibility, thermal stability, and catalytic efficiency of M-Est.

Main Methods:

• Biochemical assays to determine enzyme activity and stability.
• Computational analyses, including molecular dynamics simulations.
• Identification of the Mn2+ binding site and analysis of conformational changes.

Main Results:

• M-Est, a thermolabile esterase with optimal activity at 5°C, binds Mn2+ at a surface-exposed site near the active site.
• Mn2+ binding induces local conformational changes, surprisingly improving both thermal stability (Tm = 31.7°C) and catalytic efficiency.
• The Mn2+ binding site is conserved in related psychrophilic and psychrotolerant enzymes.

Conclusions:

• Mn2+ binding represents an atypical but potentially effective strategy to enhance the performance of cold-active enzymes.
• This finding offers insights into the mechanisms of thermal adaptation in extremophilic organisms.
• Understanding metal ion interactions can guide the engineering of enzymes for specific temperature conditions.