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Effects of Salinity and Temperature on the Flexibility and Function of a Polyextremophilic Enzyme
- Source :
- International Journal of Molecular Sciences; Volume 23; Issue 24; Pages: 15620
- Publication Year :
- 2022
- Publisher :
- Multidisciplinary Digital Publishing Institute, 2022.
-
Abstract
- The polyextremophilic β-galactosidase enzyme of the haloarchaeon Halorubrum lacusprofundi functions in extremely cold and hypersaline conditions. To better understand the basis of polyextremophilic activity, the enzyme was studied using steady-state kinetics and molecular dynamics at temperatures ranging from 10 °C to 50 °C and salt concentrations from 1 M to 4 M KCl. Kinetic analysis showed that while catalytic efficiency (kcat/Km) improves with increasing temperature and salinity, Km is reduced with decreasing temperatures and increasing salinity, consistent with improved substrate binding at low temperatures. In contrast, kcat was similar from 2–4 M KCl across the temperature range, with the calculated enthalpic and entropic components indicating a threshold of 2 M KCl to lower the activation barrier for catalysis. With molecular dynamics simulations, the increase in per-residue root-mean-square fluctuation (RMSF) was observed with higher temperature and salinity, with trends like those seen with the catalytic efficiency, consistent with the enzyme’s function being related to its flexibility. Domain A had the smallest change in flexibility across the conditions tested, suggesting the adaptation to extreme conditions occurs via regions distant to the active site and surface accessible residues. Increased flexibility was most apparent in the distal active sites, indicating their importance in conferring salinity and temperature-dependent effects.
- Subjects :
- Salinity
halophile
psychrophile
enzyme kinetics
molecular dynamics simulations
β-galactosidase
Organic Chemistry
Temperature
General Medicine
Sodium Chloride
Catalysis
Computer Science Applications
Inorganic Chemistry
Cold Temperature
Kinetics
Enzyme Stability
Physical and Theoretical Chemistry
Molecular Biology
Spectroscopy
Subjects
Details
- Language :
- English
- ISSN :
- 14220067
- Database :
- OpenAIRE
- Journal :
- International Journal of Molecular Sciences; Volume 23; Issue 24; Pages: 15620
- Accession number :
- edsair.doi.dedup.....13b5e19fdd7c88d35942fe097c67b663
- Full Text :
- https://doi.org/10.3390/ijms232415620