6u1h | pdb_00006u1h

Thermus thermophilus D-alanine-D-alanine ligase in complex with ADP, phosphate, Mg2+ and K+

spinqualitylabelsall models 6u1h, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6u1h is a 4 chain structure with sequence from Thet8. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ADP, K, MG, PO4 Related: 6u1c, 6u1d, 6u1e, 6u1f, 6u1g Gene: ddl, TTHA1587 (THET8) Activity: D-alanine--D-alanine ligase, with EC number 6.3.2.4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [DDL_THET8] Cell wall formation.[HAMAP-Rule:MF_00047] Publication Abstract from PubMed 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 the 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 Thermus thermophilus and used a combined biochemical and structural approach to characterize the MVC activation. We found that TtDdl is a Type II MVC-activated enzyme, retaining activity in the absence of MVCs. However, the efficiency of TtDdl 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 TtDdl activation. To understand the mechanism of MVC activation, we solved crystal structures of TtDdl representing distinct catalytic stages in complex with K(+), Rb(+), or Cs(+) Comparison of these structures with apo TtDdl 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. D-alanine-D-alanine ligase as a model for the activation of ATP-grasp enzymes by monovalent cations.,Pederick JL, Thompson AP, Bell SG, Bruning JB J Biol Chem. 2020 Apr 25. pii: RA120.012936. doi: 10.1074/jbc.RA120.012936. PMID:32335509 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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