Enzymes from Cold-Adapted Microorganisms. The Class C Beta-Lactamase from the Antarctic Psychrophile Psychrobacter Immobilis A5

• Published in: European Journal of Biochemistry
• Main Authors: Feller, Georges, Zekhnini, Z., Lamotte-Brasseur, Josette, Gerday, Charles
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell 1997
• Subjects: Life sciences; Biochemistry; biophysics & molecular biology; Sciences du vivant; Biochimie; biophysique & biologie moléculaire; Antarctic; The Antarctic; Antarc*
• Online Access: https://orbi.uliege.be/handle/2268/16260; https://orbi.uliege.be/bitstream/2268/16260/1/EJB_1997_betalact.pdf; https://doi.org/10.1111/j.1432-1033.1997.00186.x

peer reviewed A heat-labile beta-lactamase has been purified from culture supernatants of Psychrobacter immobilis A5 grown at 4 degrees C and the corresponding chromosomal ampC gene has been cloned and sequenced. All structural and kinetic properties clearly relate this enzyme to class C beta-lactamases. The kinetic parameters of P. immobilis beta-lactamase for the hydrolysis of some beta-lactam antibiotics are in the same range as the values recorded for the highly specialized cephalosporinases from pathogenic mesophilic bacteria. By contrast, the enzyme displays a low apparent optimum temperature of activity and a reduced thermal stability. Structural factors responsible for the latter property were analysed from the three-dimensional structure built by homology modelling. The deletion of proline residues in loops, the low number of arginine-mediated H-bonds and aromatic-aromatic interactions, the lower global hydrophobicity and the improved solvent interactions through additional surface acidic residues appear to be the main determinants of the enzyme flexibility.