6U1C
Apo form of Thermus thermophilus D-alanine-D-alanine ligase
Summary for 6U1C
| Entry DOI | 10.2210/pdb6u1c/pdb |
| Descriptor | D-alanine--D-alanine ligase (2 entities in total) |
| Functional Keywords | atp-grasp domain, atp binding, metal binding, ligase |
| Biological source | Thermus thermophilus (strain HB8 / ATCC 27634 / DSM 579) |
| Total number of polymer chains | 4 |
| Total formula weight | 143155.95 |
| Authors | Pederick, J.L.,Bruning, J.B. (deposition date: 2019-08-15, release date: 2020-05-06, Last modification date: 2023-10-11) |
| Primary citation | Pederick, J.L.,Thompson, A.P.,Bell, S.G.,Bruning, J.B. d-Alanine-d-alanine ligase as a model for the activation of ATP-grasp enzymes by monovalent cations. J.Biol.Chem., 295:7894-7904, 2020 Cited by PubMed Abstract: The ATP-grasp superfamily of enzymes shares an atypical nucleotide-binding site known as the ATP-grasp fold. These enzymes are involved in many biological pathways in all domains of life. One ATP-grasp enzyme, d-alanine-d-alanine ligase (Ddl), catalyzes ATP-dependent formation of the d-alanyl-d-alanine dipeptide essential for bacterial cell wall biosynthesis and is therefore an important antibiotic drug target. Ddl is activated by the monovalent cation (MVC) K, but despite its clinical relevance and decades of research, how this activation occurs has not been elucidated. We demonstrate here that activating MVCs bind adjacent to the active site of Ddl from and used a combined biochemical and structural approach to characterize MVC activation. We found that Ddl is a type II MVC-activated enzyme, retaining activity in the absence of MVCs. However, the efficiency of Ddl increased ∼20-fold in the presence of activating MVCs, and it was maximally activated by K and Rb ions. A strict dependence on ionic radius of the MVC was observed, with Li and Na providing little to no Ddl activation. To understand the mechanism of MVC activation, we solved crystal structures of Ddl representing distinct catalytic stages in complex with K, Rb, or Cs Comparison of these structures with apo Ddl revealed no evident conformational change on MVC binding. Of note, the identified MVC binding site is structurally conserved within the ATP-grasp superfamily. We propose that MVCs activate Ddl by altering the charge distribution of its active site. These findings provide insight into the catalytic mechanism of ATP-grasp enzymes. PubMed: 32335509DOI: 10.1074/jbc.RA120.012936 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.2 Å) |
Structure validation
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