2020/12/17 by Sanchari Bhattacharyyaa, Bhattacharyyaa, Sanchari, Shimon Bershtein +7
Biochemistry, Genetics and Molecular Biology · Engineering · #Biochemical and Molecular Research #Biochemistry #Biology #Biomolecules (q-bio.BM) #Cell Behavior (q-bio.CB) #Cell biology #DNA #DNA Repair Mechanisms #DNA damage #Dihydrofolate reductase #Enzyme #FOS: Biological sciences #Gene #Genetics #In vivo #Innovative Microfluidic and Catalytic Techniques Innovation #Intracellular #Mutation #Phenotype #Point mutation #SOS response #q-bio.BM #q-bio.CB
paper · pdf · doi:10.48550/arxiv.2012.09658
arxiv created 2020/12/17 · openalex publication_date 2020/12/17 · arxiv updated 2020/12/18 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
The relationship between sequence variation and phenotype is poorly\nunderstood. Here we use metabolomic analysis to elucidate the molecular\nmechanism underlying the filamentous phenotype of E. coli strains that carry\ndestabilizing mutations in the Dihydrofolate Reductase (DHFR). We find that\npartial loss of DHFR activity causes SOS response indicative of DNA damage and\ncell filamentation. This phenotype is triggered by an imbalance in deoxy\nnucleotide levels, most prominently a disproportionate drop in the\nintracellular dTTP. We show that a highly cooperative (Hill coefficient 2.5) in\nvivo activity of Thymidylate Kinase (Tmk), a downstream enzyme that\nphosphorylates dTMP to dTDP, is the cause of suboptimal dTTP levels. dTMP\nsupplementation in the media rescues filamentation and restores in vivo Tmk\nkinetics to almost perfect Michaelis-Menten, like its kinetics in vitro.\nOverall, this study highlights the important role of cellular environment in\nsculpting enzymatic kinetics with system level implications for bacterial\nphenotype.\n