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A number of bacterial mRNAs have no 5'UTR whatsoever, or a very short one. The complete 70S ribosome, with the help of IF2 (recruiting fMet-tRNA), [8] can simply start translating such a "leaderless" mRNA. [1] A number of factors modify the efficiency of leaderless initiation. A 5' phosphate group attached to the start codon seems near ...
Degradation of prokaryotic mRNAs is accelerated by loss of coupled translation due to increased availability of target sites of RNase E. [6] It has also been suggested that coupling of transcription with translation is an important mechanism of preventing formation of deleterious R-loops . [ 7 ]
For a protein containing n amino acids, the number of high-energy phosphate bonds required to translate it is 4n-1. [9] The rate of translation varies; it is significantly higher in prokaryotic cells (up to 17–21 amino acid residues per second) than in eukaryotic cells (up to 6–9 amino acid residues per second). [10]
Initiation of translation is regulated by the accessibility of ribosomes to the Shine-Dalgarno sequence. This stretch of four to nine purine residues are located upstream the initiation codon and hybridize to a pyrimidine-rich sequence near the 3' end of the 16S RNA within the 30S bacterial ribosomal subunit . [ 1 ]
Direct regulation of translation is less prevalent than control of transcription or mRNA stability but is occasionally used. [109] Inhibition of protein translation is a major target for toxins and antibiotics, so they can kill a cell by overriding its normal gene expression control. [110]
Phosphorylation is highly effective for controlling the enzyme activity and is the most common change after translation. [ 2 ] Many eukaryotic and prokaryotic proteins also have carbohydrate molecules attached to them in a process called glycosylation , which can promote protein folding and improve stability as well as serving regulatory functions.
A bacterial initiation factor (IF) is a protein that stabilizes the initiation complex for polypeptide translation. Translation initiation is essential to protein synthesis and regulates mRNA translation fidelity and efficiency in bacteria. [1] The 30S ribosomal subunit, initiator tRNA, and mRNA form an initiation complex for elongation. [2]
They have the ability to interact with activators to help them start or increase the rate of translation. In bacteria, they are simply called IFs (i.e.., IF1, IF2, & IF3) and in eukaryotes they are known as eIFs (i.e.., eIF1, eIF2, eIF3). [1] Translation initiation is sometimes described as three step process which initiation factors help to ...