Metabolic response to point mutations reveals principles of modulation of in vivo enzyme activity and phenotype

Translated title of the contribution: Metabolic response to point mutations reveals principles of modulation of in vivo enzyme activity and phenotype

Sanchari Bhattacharyya, Bharat V. Adkar, Jaie Woodard, Eugene I. Shakhnovich, Shimon Bershtein

Research output: Contribution to journalArticlepeer-review

Abstract

The relationship between sequence variation and phenotype is poorly understood. Here we use metabolomic analysis to elucidate the molecular mechanism underlying the filamentous phenotype of E. coli strains that carry destabilizing mutations in the Dihydrofolate Reductase (DHFR). We find that partial loss of DHFR activity causes SOS response indicative of DNA damage and cell filamentation. This phenotype is triggered by an imbalance in deoxy nucleotide levels, most prominently a disproportionate drop in the intracellular dTTP. We show that a highly cooperative (Hill coefficient 2.5) in vivo activity of Thymidylate Kinase (Tmk), a downstream enzyme that phosphorylates dTMP to dTDP, is the cause of suboptimal dTTP levels. dTMP supplementation in the media rescues filamentation and restores in vivo Tmk kinetics to almost perfect Michaelis-Menten, like its kinetics in vitro. Overall, this study highlights the important role of cellular environment in sculpting enzymatic kinetics with system level implications for bacterial phenotype.
Translated title of the contributionMetabolic response to point mutations reveals principles of modulation of in vivo enzyme activity and phenotype
Original languageEnglish
JournalarXiv PrePrint,
DOIs
StatePublished - 2019

Keywords

  • microbiology

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