Kinetic and structural studies of the reaction of Escherichia coli dihydrodipicolinate synthase with (S)-2-bromopropionate.
Acta Crystallogr D Struct Biol
; 78(Pt 7): 846-852, 2022 Jul 01.
Article
en En
| MEDLINE
| ID: mdl-35775984
ABSTRACT
Dihydrodipicolinate synthase (DHDPS) catalyzes the first committed step in the lysine-biosynthetic pathway converting pyruvate and L-aspartate-ß-semialdehyde to dihydrodipicolinate. Kinetic studies indicate that the pyruvate analog (S)-2-bromopropionate inactivates the enzyme in a pseudo-first-order process. An initial velocity pattern indicates that (S)-2-bromopropionate is a competitive inhibitor versus pyruvate, with an inhibition constant of about 8â
mM. Crystals of DHDPS complexed with (S)-2-bromopropionate formed in a solution consisting of 50â
mM HEPES pH 7.5, 18% polyethylene glycol 3350, 8â
mM spermidine, 0.2â
M sodium tartrate and 5.0â
mgâ
ml-1 DHDPS. The crystals diffracted to 2.15â
Å resolution and belonged to space group P1. The crystal structure confirms the displacement of bromine and the formation of a covalent attachment between propionate and Lys161 at the active site of the enzyme. Lys161 is the active-site nucleophile that attacks the carbonyl C atom of pyruvate and subsequently generates an imine adduct in the first half-reaction of the ping-pong enzymatic reaction. A comparison of the crystal structures of DHDPS complexed with pyruvate or (S)-2-bromopropionate indicates the covalent adduct formed from (S)-2-bromopropionate leads to a rotation of about 180° of the ß-δ C atoms of Lys61 that aligns the covalently bound propionate fairly closely with the imine adduct formed with pyruvate.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Contexto en salud:
3_ND
Problema de salud:
3_neglected_diseases
/
3_zoonosis
Asunto principal:
Propionatos
/
Escherichia coli
/
Hidroliasas
Idioma:
En
Revista:
Acta Crystallogr D Struct Biol
Año:
2022
Tipo del documento:
Article
País de afiliación:
Estados Unidos