Structural and Biochemical Analysis of the Essential Diadenylate Cyclase CdaA from Listeria monocytogenes

Abstract

The recently identified second messenger cyclic di-AMP (c-di-AMP) is involved in several important cellular processes, such as cell wall metabolism, maintenance of DNA integrity, ion transport, transcription regulation, and allosteric regulation of enzyme function. Interestingly, c-di-AMP is essential for growth of the Gram-positive model bacterium Bacillus subtilis. Although the genome of B. subtilis encodes three c-di-AMPproducing diadenlyate cyclases that can functionally replace each other, the phylogenetically related human pathogens like Listeria nionocytogenes and Staphylococcus aureus possess only one enzyme, the diadenlyate cydase CdaA. Because CdaA is also essential for growth of these bacteria, the enzyme is a promising target for the development of novel antibiotics. Here we present the first crystal structure of the L. monocytogenes CdaA diadenylate cydase domain that is conserved in many human pathogens. Moreover, biochemical characterization of the cyclase revealed an unusual metal cofactor requirement.