Metabolic Flux of N10-Formyltetrahydrofolate Plays a Critical Role in the Fidelity of Translation Initiation in Escherichia coli. Issue 19 (4th September 2020)

• Record Type: Journal Article
• Authors: Lahry, Kuldeep; Gopal, Aiswarya; Sah, Shivjee; Shah, Riyaz Ahmad; Varshney, Umesh
• Is Part Of: Journal of molecular biology. Volume 432:Issue 19(2020)
• Page Start: 5473
• Page End: 5488
• Publication Date: 2020-09-04
• Subjects: IF initiation factor -- Fmt formyltransferase -- DHFR dihydrofolate reductase -- CAT chloramphenicol acetyltransferase -- TMP trimethoprim -- THF tetrahydrofolate; Fmt -- 3GC base pairs -- i-tRNA -- N10-fTHF -- trimethoprim; Molecular biology -- Periodicals; Biology -- Periodicals; Biochemistry -- Periodicals; Bacteriology -- Periodicals; Molecular Biology -- Periodicals; Biochemistry -- Periodicals; Biologie moléculaire -- Périodiques; Biologie -- Périodiques; Biochimie -- Périodiques; Moleculaire biologie; Biochemistry; Biology; Molecular biology; Periodicals; 572.805
• DOI: 10.1016/j.jmb.2020.08.003
• Languages: English
• ISSNs: 0022-2836

Abstract

Abstract: One-carbon metabolism produces methionine and N 10 -formyl-tetrahydrofolate (N 10 -fTHF) required for aminoacylation and formylation of initiator tRNA (i-tRNA), respectively. In Escherichia coli, N 10 -fTHF is made from 5, 10-methylene-THF by a two-step reaction using 5, 10-methylene-THF dehydrogenase/cyclohydrolase (FolD). The i-tRNAs from all domains of life possess a highly conserved sequence of three consecutive G–C base pairs (3GC pairs) in their anticodon stem. A 3GC mutant i-tRNA (wherein the 3GC pairs are mutated to those found in elongator tRNA Met ) is incompetent in initiation in E. coli (even though it is efficiently aminoacylated and formylated). Here, we show that E. coli strains having mutations in FolD (G122D or C58Y or P140L) allow a plasmid encoded 3GC mutant i-tRNA to participate in initiation. In vitro, the FolD mutants are highly compromised in their dehydrogenase/cyclohydrolase activities leading to reduced production of N 10 -fTHF and decreased rates of i-tRNA formylation. The perturbation of one-carbon metabolism by trimethoprim (inhibitor of dihydrofolate reductase) phenocopies FolD deficiency and allows initiation with the 3GC mutant i-tRNA. This study reveals an important crosstalk between one-carbon metabolism and the fidelity of translation initiation via formylation of i-tRNA, and suggests that augmentation of the age old sulfa drugs with FolD inhibitors could be an important antibacterial strategy. Graphical abstract: Unlabelled Image Highlights: Met and N 10 -fTHF are used to convert tRNA fMet to fMet-tRNA fMet . Metabolic changes in N 10 -fTHF levels regulate fidelity of translation initiation. Deficiency of N 10 -fTHF results in participation of tRNA fMet at the step of elongation. Changes in N 10 -fTHF levels provide important cellular strategy for growth fitness. Use of sulfa drugs with the FolD inhibitors could serve as potent antibacterials.