TY - JOUR
T1 - Investigating the Roles of Active Site Residues in Mycobacterium tuberculosis Indole-3-glycerol Phosphate Synthase, a Potential Target for Antitubercular Agents
AU - Konas, David W.
AU - Cho, Sarah
AU - Thomas, Oshane D.
AU - Bhatti, Maryum M.
AU - Leon Hernandez, Katherine
AU - Moran, Cinthya
AU - Booter, Hedda
AU - Candela, Thomas
AU - Lacap, Joseph
AU - McFadden, Paige
AU - van den Berg, Savannah
AU - Welter, Alyssa M.
AU - Peralta, Ashley
AU - Janson, Cheryl A.
AU - Catalano, Jaclyn
AU - Goodey, Nina M.
N1 - Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.
PY - 2023/10/18
Y1 - 2023/10/18
N2 - Mycobacterium tuberculosis drug resistance is emerging and new drug targets are needed. Tryptophan biosynthesis is necessary for M. tuberculosis replication and virulence. Indole-3-glycerol phosphate synthase (IGPS) catalyzes a step in M. tuberculosis tryptophan biosynthesis and has been suggested as a potential anti-infective target, but our understanding of this enzyme is limited. To aid in inhibitor design and gain a greater mechanistic picture of this enzyme, there is a need to understand the roles of active site amino acids in ligand binding and catalysis. In this work, we explored the roles of conserved active site amino acids Glu57, Lys59, Lys119, Glu168, and Glu219. Mutation of each to Ala results in loss of all detectable activity. The Glu57Gln, Lys59Arg, Lys119Arg, Glu168Gln, and Glu219Asp mutations result in large activity losses, while Glu219Gln has enhanced activity. Analysis of the enzymatic data yields the following main conclusions: (A) Lys119 is the likely catalytic acid in the CdRP ring closure step. (B) Glu168 stabilizes a charged reaction intermediate and may also be the catalytic base. (C) Glu57, Glu219, and Lys119 form a closely arranged triad in which Glu57 and Glu219 modulate the pKa of Lys119, and thus overall activity. This increased understanding of inter- and intramolecular interactions and demonstration of the highly coordinated nature of the M. tuberculosis IGPS active site provide new mechanistic information and guidance for future work with this potential new drug target.
AB - Mycobacterium tuberculosis drug resistance is emerging and new drug targets are needed. Tryptophan biosynthesis is necessary for M. tuberculosis replication and virulence. Indole-3-glycerol phosphate synthase (IGPS) catalyzes a step in M. tuberculosis tryptophan biosynthesis and has been suggested as a potential anti-infective target, but our understanding of this enzyme is limited. To aid in inhibitor design and gain a greater mechanistic picture of this enzyme, there is a need to understand the roles of active site amino acids in ligand binding and catalysis. In this work, we explored the roles of conserved active site amino acids Glu57, Lys59, Lys119, Glu168, and Glu219. Mutation of each to Ala results in loss of all detectable activity. The Glu57Gln, Lys59Arg, Lys119Arg, Glu168Gln, and Glu219Asp mutations result in large activity losses, while Glu219Gln has enhanced activity. Analysis of the enzymatic data yields the following main conclusions: (A) Lys119 is the likely catalytic acid in the CdRP ring closure step. (B) Glu168 stabilizes a charged reaction intermediate and may also be the catalytic base. (C) Glu57, Glu219, and Lys119 form a closely arranged triad in which Glu57 and Glu219 modulate the pKa of Lys119, and thus overall activity. This increased understanding of inter- and intramolecular interactions and demonstration of the highly coordinated nature of the M. tuberculosis IGPS active site provide new mechanistic information and guidance for future work with this potential new drug target.
KW - IGPS
KW - Mycobacterium tuberculosis
KW - enzyme catalysis
KW - indole-3-glycerol phosphate synthase
KW - tryptophan biosynthesis
UR - http://www.scopus.com/inward/record.url?scp=85167926805&partnerID=8YFLogxK
U2 - 10.1021/acsbiomedchemau.3c00029
DO - 10.1021/acsbiomedchemau.3c00029
M3 - Article
AN - SCOPUS:85167926805
SN - 2694-2437
VL - 3
SP - 438
EP - 447
JO - ACS Bio and Med Chem Au
JF - ACS Bio and Med Chem Au
IS - 5
ER -