Elongation Factors EFIA and EF-Tu: Their Role in Translation and Beyond

Protein biosynthesis is a central process in cell life. Although the ribosome provides the machinery for biosynthesis, successful translation of the information contained in mRNA also relies on a number of protein factors that transiently associate with this giant ribonucleic complex. Among them, the elongation factors EF-Tu (bacteria) and EFIA (eukarya and archaea), which carry the aa-tRNA to the ribosome, have earned a special consideration. Here we present an excursus of structural information collected in the last decade on these enzymes. A significant advance in this field has been the recent crystallographic characterization of the complex between ribosome and EF-Tu. These findings, along with structural studies performed on EF-Tu complexes with small molecules and proteins, have provided a picture of the interactions of these proteins with a differentiate variety of biological partners. In contrast to EF-Tu, the structural characterization of the states assumed by archaeal and eukaryal EFIA is largely incomplete. Here we also review solution and computational studies that have been successfully applied to integrate and complement crystallographic data. Analogies and differences between EFs isolated from different organisms will be highlighted. The new challenges of this research area, including the structural interpretation of the role of these proteins in other biological processes, are also addressed.