Crystal structures of the c-di-AMP-synthesizing enzyme CdaA.
Heidemann, J.L., Neumann, P., Dickmanns, A., Ficner, R.(2019) J Biol Chem 294: 10463-10470
- PubMed: 31118276 
- DOI: https://doi.org/10.1074/jbc.RA119.009246
- Primary Citation of Related Structures:  
6HVL, 6HVM, 6HVN - PubMed Abstract: 
Cyclic di-AMP (c-di-AMP) is the only second messenger known to be essential for bacterial growth. It has been found mainly in Gram-positive bacteria, including pathogenic bacteria like Listeria monocytogenes CdaA is the sole diadenylate cyclase in L. monocytogenes , making this enzyme an attractive target for the development of novel antibiotic compounds. Here we report crystal structures of CdaA from L. monocytogenes in the apo state, in the post-catalytic state with bound c-di-AMP and catalytic Co 2+ ions, as well as in a complex with AMP. These structures reveal the flexibility of a tyrosine side chain involved in locking the adenine ring after ATP binding. The essential role of this tyrosine was confirmed by mutation to Ala, leading to drastic loss of enzymatic activity.
Organizational Affiliation: 
From the Department of Molecular Structural Biology, Institute for Microbiology and Genetics, Göttingen Center for Molecular Biosciences, Georg-August-University Göttingen, 37077 Göttingen, Germany.