Adenylate kinase

Adenylate kinase (ADK, EC number 2.7.4.3) is a phosphotransferase which catalyzes the interconversion of ADP to ATP+AMP. ADK is important in cellular energy homeostasis. Dinucleotides polyphosphates like diadenosine pentaphosphate (AP5) inhibit ADK.

        Adenylate kinase is an essential catalyst for cellular growth and multiplication. ADK belongs to a family of enzymes essential to life, and is highly abundant inside the cell. It is involved in the reversible transfer of the terminal phosphate group from Mg2+ATP to Mg2+AMP with high energy turnover: Mg2+ATP + AMP↔Mg2+ADP + ADP.

        Adenylate kinases (ADK) from Gram-negative bacteria are generally devoid of metal ions in their LID domain. However, , zinc, cobalt and iron, have been found in ADK from Gram-negative bacteria. Crystal structures of substrate-free ADK from Desulfovibrio gigas with three different metal ions: (2xb4); (3l0s) and (3l0p) bound in its LID domain have been determined by X-ray crystallography. to each other with the same LID domain topology, the only change being the presence of the different metal atoms.

        The structures of Zn- , Co- and Fe-ADK contain the and , which also include the AMP binding region. The LID domain harbors the , which is responsible for metal binding in a tetrahedral fashion. In the absence of any substrate, the LID domain of all holo forms of ADK was present in a fully open conformational state. The Core domain is . This Core domain mainly consists of a that keep the integrity of the tertiary structure of the enzyme. A with conserved sequence; G-X-X-G-X-G-K is present in the N-terminal region. The structures presented herein further reinforce the notion that the metal ion is purely structural, contributing to the stability of the LID domain.^[1]