title: Temperature dependent mistranslation in a hyperthermophile adapts proteins to lower temperatures.
abstract: All organisms universally encode, synthesize and utilize proteins that function optimally within a subset of growth conditions. While healthy cells are thought to maintain high translational fidelity within their natural habitats, natural environments can easily fluctuate outside the optimal functional range of genetically encoded proteins. The hyperthermophilic archaeon Aeropyrum pernix (A. pernix) can grow throughout temperature variations ranging from 70 to 100°C, although the specific factors facilitating such adaptability are unknown. Here, we show that A. pernix undergoes constitutive leucine to methionine mistranslation at low growth temperatures. Low-temperature mistranslation is facilitated by the misacylation of tRNA(Leu) with methionine by the methionyl-tRNA synthetase (MetRS). At low growth temperatures, the A. pernix MetRS undergoes a temperature dependent shift in tRNA charging fidelity, allowing the enzyme to conditionally charge tRNA(Leu) with methionine. We demonstrate enhanced low-temperature activity for A. pernix citrate synthase that is synthesized during leucine to methionine mistranslation at low-temperature growth compared to its high-fidelity counterpart synthesized at high-temperature. Our results show that conditional leucine to methionine mistranslation can make protein adjustments capable of improving the low-temperature activity of hyperthermophilic proteins, likely by facilitating the increasing flexibility required for greater protein function at lower physiological temperatures.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA Committee on Microbiology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Schwartz
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA Committee on Microbiology, University of Chicago, 929 E. 57th St., Chicago, IL 60637, USA taopan@uchicago.edu.
authors.forename: Tao
authors.initials: T
authors.lastname: Pan
mesh_terms: D041522:Aeropyrum / Q000502:physiology*; D019943:Amino Acid Substitution; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002950:Citrate (si)-Synthase / Q000737:chemistry / Q000378:metabolism; D008718:Methionine-tRNA Ligase / Q000378:metabolism; D008958:Models, Molecular; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D046249:Transfer RNA Aminoacylation
chemical_list: D019843:Archaeal Proteins; D012343:RNA, Transfer; D002950:Citrate (si)-Synthase; D008718:Methionine-tRNA Ligase