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Translation is one of the key energy consumers in cells, hence it is strictly regulated. Numerous mechanisms have evolved that control and regulate translation in eukaryotes as well as prokaryotes. Regulation of translation can impact the global rate of protein synthesis which is closely coupled to the metabolic and proliferative state of a cell.
Initiation of translation in bacteria involves the assembly of the components of the translation system, which are: the two ribosomal subunits (50S and 30S subunits); the mature mRNA to be translated; the tRNA charged with N-formylmethionine (the first amino acid in the nascent peptide); guanosine triphosphate (GTP) as a source of energy, and the three prokaryotic initiation factors IF1, IF2 ...
In prokaryotes (bacteria and archaea), translation occurs in the cytosol, where the large and small subunits of the ribosome bind to the mRNA. In eukaryotes, translation occurs in the cytoplasm or across the membrane of the endoplasmic reticulum through a process called co-translational translocation.
Bacterial transcription is the process in which a segment of bacterial DNA is copied into a newly synthesized strand of messenger RNA (mRNA) with use of the enzyme RNA polymerase. The process occurs in three main steps: initiation, elongation, and termination; and the result is a strand of mRNA that is complementary to a single strand of DNA.
Electron micrographs of stained cell-free protein synthesis reactions revealed branched assemblies in which strings of ribosomes are linked to a central DNA fibre. [27] DNA isolated from bacterial cells co-sediment with ribosomes, further supporting the conclusion that transcription and translation occur together. [26]
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 ]
A eukaryotic cell has a nucleus that separates the processes of transcription and translation. Eukaryotic transcription occurs within the nucleus where DNA is packaged into nucleosomes and higher order chromatin structures. The complexity of the eukaryotic genome necessitates a great variety and complexity of gene expression control. Eukaryotic ...
Initiation factors can interact with repressors to slow down or prevent translation. 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]