The Potential of a Protein Model Synthesized Absent of Methionine

Abstract

Methionine is an amino acid long thought to be essential, but only in the case of protein synthesis initiation. In more recent years, methionine has been found to play an important role in antioxidant defense, stability, and modulation of cell and protein activity. Though these findings have expanded the previously held sentiment of methionine having a singular purpose within cells and proteins, the essential nature of methionine can still be challenged. Many of the features that give methionine its newfound functions are shared by the other sulfur-containing amino acid: cysteine. While the antioxidant, stabilizing, and cell/protein modulatory functions of cysteine have already been well established, recent findings have shown a similar hydrophobicity to methionine which suggests cysteine may be able to replace methionine in all functions outside of protein synthesis initiation with little effect on cell and protein function. Furthermore, a number of novel mechanisms for alternative initiation of protein synthesis have been identified that suggest a potential to bypass the traditional methionine-dependent initiation during times of stress. In this review, these findings are discussed with a number of examples that demonstrate a potential model for synthesizing a protein in the absence of methionine.

Highly chromophoric fluorescent‐labeled methionyl‐initiator tRNAs applicable in living cells

“…This is consistent with a previous [ 33 ] that demonstrated PFM‐tRNAi Met complex‐mediated expression of fluorescently tagged proteins via intracellular PFM substitution under met deficiency. [ 40 ]…”

“…This is consistent with a previous [33] that demonstrated PFM-tRNAi Met complex-mediated expression of fluorescently tagged proteins via intracellular PFM substitution under met deficiency. [40] The intracellular production of Fluo-Met-tRNAi Met utilizes PFMendogenous tRNAi Met , which is generated by incubating PFM alone in a met-deficient medium. This allows endogenous tRNAi and HMRS to carry out the methionyl reaction with PFM, forming the Fluo-Met-tRNAi Met product.…”

Effects of dietary methionine supplementation on the growth performance, immune responses, antioxidant capacity, and subsequent development of layer chicks

“…Met is the main limiting amino acid in corn-soya meal-based laying hen diets ( Rama Rao et al, 2019 ; Beheshti Moghadam et al, 2021 ), and provides organic sulfur elements. Met has been shown to be indispensable for protein synthesis, the growth and development, and the immune function of animals, and either an excess or a deficiency of Met affects the growth performance of poultry ( Elango, 2020a ; Savino et al, 2022 ). In the present study, Met supplementation improved the growth performance, immune status, and antioxidant capacity of chicks.…”

Nutritional value evaluation of wild edible mushroom (Helvella leucopus) from western China

“…As EAA, Met exerts certain effects on liver cirrhosis, fatty liver, and cardiovascular diseases. It also promotes antioxidant defence, and modulates cell and protein activities (Savino et al, 2022). Moreover, a diet deficient in Met can affect DNA methylation (Aissa et al, 2022).…”