D-alanine:D-alanine ligase (DDl) is an essential enzyme in bacterial cell wall biosynthesis and an important target for developing new antibiotics. It catalyzes the formation of D-alanine:D-alanine dipeptide, sequentially by using one D-alanine and one ATP as substrates for the first-half reaction, and a second D-alanine substrate to complete the reaction. Some gain of function DDl mutants can use an alternate second substrate, causing resistance to vancomycin, one of the last lines of defense against life-threatening Gram-positive infections. Here, we report the crystal structure of Staphylococcus aureus DDl (StaDDl) and its cocrystal structures with 3-chloro-2,2-dimethyl-N-[4(trifluoromethyl)phenyl]propanamide (inhibitor 1) (Ki=4 microM against StaDDl) and with ADP, one of the reaction products, at resolutions of 2.0, 2.2, and 2.6 A, respectively. The overall structure of StaDDl can be divided into three distinct domains. The inhibitor binds to a hydrophobic pocket at the interface of the first and the third domain. This inhibitor-binding pocket is adjacent to the first D-alanine substrate site but does not overlap with any substrate sites. An allosteric inhibition mechanism of StaDDl by this compound was proposed. The mechanism provides the basis for developing new antibiotics targeting D-alanine:D-alanine ligase. Because this compound only interacts with residues from the first D-alanine site, inhibitors with this binding mode potentially could overcome vancomycin resistance.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1622796 | PMC |
http://dx.doi.org/10.1073/pnas.0604905103 | DOI Listing |
J Agric Food Chem
July 2020
Engineering Research Center of Industrial Microbiology, Ministry of Education; Collaborative Innovation Center of Haixi Green Bio-Manufacturing Technology, Ministry of Education; College of Life Sciences, Fujian Normal University, Fuzhou 350117, P. R. China.
, a pathogenic bacterium, is harmful to humans, domestic animals, and fishes and, moreover, of public health concern due to the emergence of multiple drug-resistant strains. The cell wall has been discovered as a novel and efficient drug target against bacteria, and d-alanine-d-alanine ligase (Ddl) is considered as an essential enzyme in bacterial cell wall biosynthesis. Herein, we studied the HBNUAh01 Ddl (Ddl) enzyme activity and kinetics and determined the crystal structure of Ddl/d-Ala complex at 2.
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