Selection of AUG initiation codons differs in plants and animals.

Abstract

The influence of the nucleotide at position ‐3 relative to the AUG initiation codon on the initiation of protein synthesis was studied in two different in vitro translation systems using synthetic mRNAs. The four mRNAs, transcribed from cDNAs directed by an SP6 promoter, were identical except for mutations at nucleotide ‐3. In each case, translation of mRNAs produced a single protein of Mr = 12,600. Relative translational efficiencies showed a hierarchy in the reticulocyte lysate system (100, 85, 61 and 38% for A, G, U and C in position ‐3, respectively) but no differences in the wheat germ system. Differential mRNA degradation or polypeptide chain elongation were excluded as causes of the differences observed in translation in the reticulocyte lysate. mRNA competition increased the differences observed in translational efficiencies in reticulocyte lysate but showed no effect in wheat germ. Analysis of 61 plant and 209 animal mRNA sequences revealed qualitative and quantitative differences between the consensus sequences surrounding AUG initiation codons. Whereas the consensus sequence for animals was CACCAUG that for plants was AACAAUGGC. Both the structural and functional findings suggest that the factors which select AUG initiation codons in plants and animals differ significantly.

Expression of sunflower low-molecular-weight heat-shock proteins during embryogenesis and persistence after germination: localization and possible functional implications

“…Preliminary observations in our laboratory (10) and other groups [15][16][17][18][19][20][21][22][23][24][25][26][27][28]29] indicated expression of LMW HSPs during zygotic embryogenesis and seed germination. The results presented in this paper demonstrate differential developmental expression of two distinct families of cytoplasmic proteins.…”

“…1). Sequences in the vicinity of the latter show similarity to the plant translation initiation consensus [23]. The only plausible open reading frame (ORF) present in Ha hspl7.9 is flanked by a relatively short leader (24 nt) and a long trailer (312 nt).…”

Multiple isoforms of Pisum trypsin inhibitors result from modification of two primary gene products

“…2B) would be considered favourable as an initiator, based on the three preceding nucleotides (Fig. 2C) [20].…”

High‐level expression of Pinus sylvestris glutamine synthetase in Escherichia coli

“…2, lane 4) strongly suggested that translation of the gene construction starts in the first ATG of the cDNA and therefore recombinant GS subunit is expected to be constituted by 357 amino acid residues [7]. However, the pine sequence contains a second in-frame ATG codon at 93 bp that would define an additional open reading frame which would encode a polypeptide of 326 amino acids (about 3 kDa smaller in size) [20]. Regarding the second hypothesis, it is well documented that endogenous GS in E. coli is marked by oxidative modification becoming susceptible to proteolytic degradation [16,17,26].…”