Comparative analysis of glycerol kinase from the bacterium Listeria monocytogenes and the archaean Sulfolobus islandicus

Glycerol kinase is an enzyme that catalyzes the phosphorylation of glycerol to glycerol 3-phosphate, a reaction critical for metabolic functions from carbohydrate metabolism to lipid synthesis. This study compared catalytic and structural properties of the enzyme glycerol kinase from two highly different organisms. Glycerol kinase from the bacterium Listeria monocytogenes , an organism that grows at low temperatures and poses a significant risk of foodborne illness, was optimally active at 4°C. As shown by circular dichroism (CD) analysis, L. monocytogenes glycerol kinase is not stable at high temperatures and denatured with a melting temperature (T m ) of 46°C. Glycerol kinase from the archaean Sulfolobus islandicus , however, displayed quite different behavior. The enzyme was optimally active at considerably high temperatures, possessing maximal activity at the highest temperature tested of 90°C. Consistent with activity at higher temperatures, S. islandicus glycerol kinase did not exhibit thermal denaturation. CD spectra at 20°C and 75°C indicated a change in secondary structure that may contribute to enzyme activation at high temperatures.