The role of quaternary structure in (beta/alpha)(8)-barrel proteins: evolutionary happenstance or a higher level of structure-function relationships?

Despite significant effort, the role played by quaternary structure in enzymes often remains poorly understood. The (beta/alpha)(8)-barrel fold is a versatile scaffold that has been employed in a wide variety of organisms to catalyse a broad spectrum of reactions, and thus is a convenient motif for further investigation into the importance and role of quaternary structure. This review will highlight studies in which the interplay between catalytic activity and quaternary structure in the (beta/alpha)(8)-barrel family have been explored, revealing examples in which homo-oligomeric structure completes the active site or apparently enhances thermal stability. More recently, results have pointed to the importance of quaternary structure in tuning dynamic motion to optimise catalytic activity.