Abstact

The tertiary fold of the elongation factor, aEF-1beta, from Methanobacterium thermoautotrophicum was determined in a high-throughput fashion using a minimal set of NMR experiments. NMR secondary structure prediction, deuterium exchange experiments and the analysis of chemical shift perturbations were combined to identify the protein fold as an alpha-beta sandwich typical of many RNA binding proteins including EF-G. Following resolution of the tertiary fold, a high resolution structure of aEF-1beta was determined using heteronuclear and homonuclear NMR experiments and a semi-automated NOESY assignment strategy. Analysis of the aEF-1beta structure revealed close similarity to its human analogue, eEF-1beta. In agreement with studies on EF-Ts and human EF-1beta, a functional mechanism for nucleotide exchange is proposed wherein Phe46 on an exposed loop acts as a lever to eject GDP from the associated elongation factor G-protein, aEF-1alpha. aEF-1beta was also found to bind calcium in the groove between helix alpha2 and strand beta4. This novel feature was not observed previously and may serve a structural function related to protein stability or may play a functional role in archaeal protein translation.