Effects of single amino acid deficiency on mRNA translation are markedly different for methionine versus leucine

Sci Rep. 2018 May 24;8(1):8076. doi: 10.1038/s41598-018-26254-2.

Abstract

Although amino acids are known regulators of translation, the unique contributions of specific amino acids are not well understood. We compared effects of culturing HEK293T cells in medium lacking either leucine, methionine, histidine, or arginine on eIF2 and 4EBP1 phosphorylation and measures of mRNA translation. Methionine starvation caused the most drastic decrease in translation as assessed by polysome formation, ribosome profiling, and a measure of protein synthesis (puromycin-labeled polypeptides) but had no significant effect on eIF2 phosphorylation, 4EBP1 hyperphosphorylation or 4EBP1 binding to eIF4E. Leucine starvation suppressed polysome formation and was the only tested condition that caused a significant decrease in 4EBP1 phosphorylation or increase in 4EBP1 binding to eIF4E, but effects of leucine starvation were not replicated by overexpressing nonphosphorylatable 4EBP1. This suggests the binding of 4EBP1 to eIF4E may not by itself explain the suppression of mRNA translation under conditions of leucine starvation. Ribosome profiling suggested that leucine deprivation may primarily inhibit ribosome loading, whereas methionine deprivation may primarily impair start site recognition. These data underscore our lack of a full understanding of how mRNA translation is regulated and point to a unique regulatory role of methionine status on translation initiation that is not dependent upon eIF2 phosphorylation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing / metabolism
  • Amino Acids / deficiency*
  • Amino Acids / pharmacology*
  • Cell Cycle Proteins
  • Culture Media / chemistry
  • Culture Media / pharmacology
  • Eukaryotic Initiation Factor-2 / metabolism
  • Eukaryotic Initiation Factor-4E / metabolism
  • HEK293 Cells
  • Humans
  • Leucine / deficiency*
  • Leucine / pharmacology
  • Methionine / deficiency*
  • Methionine / pharmacology
  • Phosphoproteins / metabolism
  • Phosphorylation / drug effects
  • Protein Biosynthesis / drug effects*
  • RNA, Messenger / metabolism
  • Ribosomes / drug effects
  • Ribosomes / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Amino Acids
  • Cell Cycle Proteins
  • Culture Media
  • EIF4EBP1 protein, human
  • Eukaryotic Initiation Factor-2
  • Eukaryotic Initiation Factor-4E
  • Phosphoproteins
  • RNA, Messenger
  • Methionine
  • Leucine