High-Order Epistasis in Catalytic Power of Dihydrofolate Reductase Gives Rise to a Rugged Fitness Landscape in the Presence of Trimethoprim Selection

Yusuf Talha Tamer, Ilona K. Gaszek, Haleh Abdizadeh, Tugce Altinusak Batur, Kimberly A. Reynolds, Ali Rana Atilgan, Canan Atilgan, Erdal Toprak

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Evolutionary fitness landscapes of several antibiotic target proteins have been comprehensively mapped showing strong high-order epistasis between mutations, but understanding these effects at the biochemical and structural levels remained open. Here, we carried out an extensive experimental and computational study to quantitatively understand the evolutionary dynamics of Escherichia coli dihydrofolate reductase (DHFR) enzyme in the presence of trimethoprim-induced selection. To facilitate this, we developed a new in vitro assay for rapidly characterizing DHFR steady-state kinetics. Biochemical and structural characterization of resistance-conferring mutations targeting a total of ten residues spanning the substrate binding pocket of DHFR revealed distinct changes in the catalytic efficiencies of mutated DHFR enzymes. Next, we measured biochemical parameters (Km, Ki, and kcat) for a mutant library carrying all possible combinations of six resistance-conferring DHFR mutations and quantified epistatic interactions between them. We found that the high-order epistasis in catalytic power of DHFR (kcat and Km) creates a rugged fitness landscape under trimethoprim selection. Taken together, our data provide a concrete illustration of how epistatic coupling at the level of biochemical parameters can give rise to complex fitness landscapes, and suggest new strategies for developing mutant specific inhibitors.

Original languageEnglish (US)
Pages (from-to)1533-1550
Number of pages18
JournalMolecular biology and evolution
Volume36
Issue number7
DOIs
StatePublished - Jul 1 2019

Fingerprint

dihydrofolate reductase
epistasis
Tetrahydrofolate Dehydrogenase
Trimethoprim
trimethoprim
mutation
fitness
enzyme
antibiotics
Mutation
targeting
inhibitor
substrate
kinetics
mutants
protein
Enzymes
enzymes
catalytic activity
Escherichia coli

Keywords

  • antibiotic resistance
  • epistasis
  • experimental evolution
  • molecular evolution
  • protein evolution

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics

Cite this

High-Order Epistasis in Catalytic Power of Dihydrofolate Reductase Gives Rise to a Rugged Fitness Landscape in the Presence of Trimethoprim Selection. / Tamer, Yusuf Talha; Gaszek, Ilona K.; Abdizadeh, Haleh; Batur, Tugce Altinusak; Reynolds, Kimberly A.; Atilgan, Ali Rana; Atilgan, Canan; Toprak, Erdal.

In: Molecular biology and evolution, Vol. 36, No. 7, 01.07.2019, p. 1533-1550.

Research output: Contribution to journalArticle

Tamer, Yusuf Talha ; Gaszek, Ilona K. ; Abdizadeh, Haleh ; Batur, Tugce Altinusak ; Reynolds, Kimberly A. ; Atilgan, Ali Rana ; Atilgan, Canan ; Toprak, Erdal. / High-Order Epistasis in Catalytic Power of Dihydrofolate Reductase Gives Rise to a Rugged Fitness Landscape in the Presence of Trimethoprim Selection. In: Molecular biology and evolution. 2019 ; Vol. 36, No. 7. pp. 1533-1550.
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