Dynamics of glyphosate-induced conformational changes of Mycobacterium tuberculosis 5-enolpyruvylshikimate-3-phosphate synthase (EC 2.5.1.19) determined by hydrogen-deuterium exchange and electrospray mass spectrometry.
The enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) catalyzes the reaction between shikimate 3-phosphate and phosphoenolpyruvate to form 5-enolpyruvylshikimate 3-phosphate, an intermediate in the shikimate pathway, which leads to the biosynthesis of aromatic amino acids. EPSPS exists in an open conformation in the absence of substrates and/or inhibitors and in a closed conformation when bound to the substrate and/or inhibitor. In the present report, the H/D exchange properties of EPSPS from Mycobacterium tuberculosis ( Mt) were investigated for both enzyme conformations using ESI mass spectrometry and circular dichroism (CD). When the conformational changes identified by H/D exchanges were mapped on the 3-D structure, it was observed that the apoenzyme underwent extensive conformational changes due to glyphosate complexation, characterized by an increase in the content of alpha-helices from 40% to 57%, while the beta-sheet content decreased from 30% to 23%. These results indicate that the enzyme underwent a series of rearrangements of its secondary structure that were accompanied by a large decrease in solvent access to many different regions of the protein. This was attributed to the compaction of 71% of alpha-helices and 57% of beta-sheets as a consequence of glyphosate binding to the enzyme. Apparently, MtEPSPS undergoes a series of inhibitor-induced conformational changes, which seem to have caused synergistic effects in preventing solvent access to the core of molecule, especially in the cleft region. This may be part of the mechanism of inhibition of the enzyme, which is required to prevent the hydration of the substrate binding site and also to induce the cleft closure to avoid entrance of the substrates.
Laboratory of Structural Biology and Zoochemistry, CEIS/Department of Biology, Institute of Biosciences, UNESP, Rio Claro, SP 13506-900, Brazil.
Maurício R
MR
Marques
Alessandra
A
Vaso
João Ruggiero
JR
Neto
Marcelo A
MA
Fossey
Jaim S
JS
Oliveira
Luiz A
LA
Basso
Diógenes S
DS
dos Santos
Walter F
WF
de Azevedo Junior
Mario S
MS
Palma
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D001051:Apoenzymes / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D003903:Deuterium; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006859:Hydrogen; D007700:Kinetics; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology*; D010449:Peptide Mapping; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D000097797:Glyphosate
D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D001051:Apoenzymes; D003903:Deuterium; D005998:Glycine; D006859:Hydrogen; D011994:Recombinant Proteins; D000097797:Glyphosate