Psychrophilic enzymes: strategies for cold-adaptation

Abstract

Psychrophilic organisms thriving at near-zero temperatures synthesize cold-adapted enzymes to sustain cell metabolism. These enzymes have overcome the reduced molecular kinetic energy and increased viscosity inherent to their environment and maintained high catalytic rates by development of a diverse range of structural solutions. Most commonly, they are characterized by a high flexibility coupled with an intrinsic structural instability and reduced substrate affinity. However, this paradigm for cold-adaptation is not universal as some cold-active enzymes with high stability and/or high substrate affinity and/or even an unaltered flexibility have been reported, pointing to alternative adaptation strategies. Indeed, cold-adaptation can involve any of a number of a diverse range of structural modifications, or combinations of modifications, depending on the enzyme involved, its function, structure, stability, and evolutionary history. This paper presents the challenges, properties, and adaptation strategies of these enzymes.

Low-temperature features of the psychrophilic chaperonin from Pseudoalteromonas haloplanktis

“…Typically, interaction of chaperonins with their clients is mediated by the interaction of exposed hydrophobic surfaces in the unfolded client protein with hydrophobic patches at the inside of the Cpn60 cylinder. However, hydrophobic interactions are weakened when temperature is decreased, whereas electrostatic interactions are strengthened (Papaleo et al 2007 , 2011 ; Collins and Feller 2023 ). Thus, Ph Cpn60 might bind a different set of client proteins, or bind it differently, resulting also in different dynamics of release for a given protein.…”