Interdomain interactions in oligomeric enzymes: creation of asymmetry in homo-oligomers and role in metabolite channeling between active centers of hetero-oligomers.

Interdomain interactions play an important role in the structural organization of many enzymes and the conformational flexibility of their molecules. In this review, the role of intrasubunit and intersubunit domain-domain interactions in the origins of pre-existent asymmetry of homo-oligomeric D-glyceraldehyde-3-phosphate dehydrogenase and tryptophanyl-tRNA synthetase is discussed on the basis of recent X-ray data and other available information about the properties of these and related enzymes. In addition, a novel key function of interdomain interactions is considered: their potential contribution to intramolecular channeling of intermediates between active centers located on different subunits of a hetero-oligomeric enzyme (alpha,beta-heterodimeric carbamoyl phosphate synthetase).