Structure-Function Relationships in Temperature Effects on Bacterial Luciferases: Nothing Is Perfect

Area of Science:

• Biochemistry
• Enzymology
• Structural Biology

Background:

• Enzyme function is temperature-dependent, crucial for understanding environmental adaptation.
• Luciferases from different bacterial subfamilies exhibit varied responses to temperature.
• Investigating enzyme stability and activity under thermal stress is vital.

Purpose of the Study:

• To investigate temperature effects on the activity, dynamics, and stability of *Photobacterium leiognathi* and *Vibrio harveyi* luciferases.
• To explore the role of sucrose in maintaining enzyme function and stability under varying temperatures.
• To compare the thermal adaptation mechanisms of luciferases from different subfamilies.

Main Methods:

• Stopped-flow technique to measure enzyme activity and inactivation rates.
• Differential scanning calorimetry (DSC) to assess thermal denaturation.
• Molecular dynamics simulations to analyze structural dynamics and features.

Main Results:

• *P. leiognathi* luciferase showed high activity in a narrow temperature range, characteristic of cold-adapted enzymes, with lower thermal stability than *V. harveyi* luciferase.
• *V. harveyi* luciferase exhibited lower activity but greater thermostability.
• Differences in activity were linked to mobile loop conformational changes.
• Sucrose increased enzyme stability without enhancing activity.
• DSC indicated distinct denaturation pathways for the two luciferases.

Conclusions:

• *P. leiognathi* and *V. harveyi* luciferases possess different thermal adaptation strategies.
• Enzyme structural dynamics, particularly mobile loops, influence temperature-dependent activity.
• Sucrose can be utilized as a stabilizing agent for enzymes.
• Understanding these temperature-driven mechanisms is key for enzyme applications in diverse environments.