The structure of a tautomerase superfamily member linked to the type VI secretion system of Acinetobacter baumannii

Bacteria exploit specialized secretion systems to assist in competition for resources, in collaboration and in communication. Here, a protocol for the recombinant production, purification and crystallization of a protein linked to the Acinetobacter baumannii type VI secretion system is provided. A high‐resolution structure of this trimeric protein is reported, revealing the characteristic dual β–α–β subunit fold typical of longer subunit members of the tautomerase superfamily. The protein does not appear to be toxic to bacteria or yeast under the conditions tested. The possible biological role of this protein is discussed. The high‐resolution crystal structure of an Acinetobacter baumannii protein previously reported as being dependent on the type VI secretion system has been determined. Structural and sequence comparisons reveal significant conservation with the tautomerase superfamily of enzymes, which are not generally noted as being associated with this secretion system. The protein does not display toxicity when produced in either a bacterial or a yeast system. The implications of these observations are discussed.