Novel properties of bacterial elongation factor Tu.

We have characterized novel properties of the bacterial protein synthesis elongation factor Tu which indicate that it may function as a structural protein. Under appropriate conditions, elongation factor Tu polymerizes to form filaments and, more often, bundles of filaments. It is also the predominant component of a complex of proteins from Escherichia coli that undergoes reversible polymerization in the presence of KCl and MgCl2. In addition, purified elongation factor Tu binds tightly to DNase I in the presence of 10 mM MgCl2. In crude extracts the factor shows no binding in the presence or absence of MgCl2. These properties suggest that elongation factor Tu may have certain actin-like properties and that it has cellular functions other than its role in protein synthesis.