Searching for Dihydrodipicolinate Synthase Inhibitors as a Possible Antibiotic

Abstract

Dihydrodipicolinate Synthase (DHDPS) is the enzyme that catalyzes the first step in the lysine biosynthetic pathway. Lysine is an essential amino acid in humans and should be obtained through diet. Enzyme catalysis is initiated through binding of the first substrate, pyruvate, to the active site of DHDPS. The binding of the second substrate, ASA, is believed to form 2, 3-dihydrodipicolinate. Finding a tight-binding inhibitor for DHDPS in the lysine biosynthetic pathway will generate a compound which is a candidate for antibacterial drug design. Kinetic studies of DHDPS and the inhibitor of the enzyme 2-bromopropionic acid showed that 2-bromopropionic acid is the competitive inhibitor of the enzyme versus pyruvate. Inhibition constant was determined to be 8.3 ± 0.8 mM. Crystals of DHDPS in complex with 2-bromoproprionic acid are formed at pH 7.5 in the presence of 8 mM 2-bromoproprionate, ~20% PEG 3350, 10 mM spermidine, 200 mM sodium tartrate, and 5.5 mg/mL DHDPS. Bacterial culture viability experiments indicate that 2-bromoproprionic acid inhibits the growth of Escherichia coli harboring DapA gene by 90%. *This research is funded by Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under grant number P20GM103447 and P20GM103640 (OCAST).