translation

Examples of translation in the following topics:

• Regulation of Sigma Factor Translation

  • The regulation of expression of sigma factors occurs at transcriptional, translational, and post-translational levels as dictated by the cellular environment and the presence or absence of numerous cofactors.
  • Specifically, the translational control of the sigma factor is a major level of control.
  • The translational control of sigma factors involves the presence and function of small noncoding RNAs.
  • The small noncoding RNAs are able to specifically increase the amount of rpoS mRNA that undergoes translation.
  • These RNAs can induce activation of rpoS translation.

• Attenuation

  • Attenuation is a regulatory mechanism used in bacterial operons to ensure proper transcription and translation.
  • In bacteria, transcription and translation are capable of proceeding simultaneously.
  • Hence, attenuators can function in either transcription-attenuation or translation-attenuation.
  • Translation-attenuation is characterized by the sequestration of the Shine-Dalgarno sequence.
  • Hence, this specific process is referred to as translation-attenuation.

• Unsticking Stuck Ribosomes

  • Ribosomes translating the mRNA eventually translate into the 3'poly-A tail region of transcripts and stalls.
  • There are two ways in which cells deal with stuck ribosomes, nonstop mediated decay (NSD) and Trans-translation.
  • rans-Translation stages A through F.
  • Regular translation eventually resumes.
  • Differentiate between nonstop mediated decay and trans-translation as mechanisms of freeing stuck ribosomes

• RNA Regulation and Antisense RNA

  • Antisense RNAs are single-stranded RNA molecules that can bind and inhibit specific mRNA translation to protein.
  • The antisense RNA can physically pair and bind to the complementary mRNA, thus inhibiting the ability of the mRNA to be processed in the translation machinery.
  • Hence, E. coli utilizing this system can regulate the expression of hok (toxin) and inhibits its translation by producing sok RNA (antitoxin).
  • The outcome is the repression of hok mRNA translation.

• Prokaryotic Transcription and Translation Are Coupled

  • Prokaryotic transcription occurs in the cytoplasm alongside translation and can occur simultaneously.
  • Prokaryotic transcription occurs in the cytoplasm alongside translation .
  • Prokaryotic transcription and translation can occur simultaneously.
  • This is impossible in eukaryotes, where transcription occurs in a membrane-bound nucleus while translation occurs outside the nucleus in the cytoplasm.
  • The DNA on the template strand between the +1 site and the terminator is transcribed into RNA, which is then translated into protein.

• Small Regulatory RNAs

  • Antisense RNAs are used to bind to complementary mRNAs and inhibit protein translation.
  • Antisense RNAs are single stranded RNAs that can be utilized as a laboratory technique to inhibit protein translation.
  • These RNAs can either activate or inhibit RPoS translation.
  • The antisense RNA can bind to the mRNA and inhibit translation.
  • In some cases, small regulatory RNAs, not included in the antisense category, can activate translation as well.

• Inhibiting Protein Synthesis

  • Translation in prokaryotes involves the assembly of the components of the translation system which are: the two ribosomal subunits (the large 50S & small 30S subunits), the mRNA to be translated, the first aminoacyl tRNA, GTP (as a source of energy), and three initiation factors that help the assembly of the initiation complex .
  • In general, protein synthesis inhibitors work at different stages of prokaryotic mRNA translation into proteins like initiation, elongation (including aminoacyl tRNA entry, proofreading, peptidyl transfer, and ribosomal translocation), and termination.
  • By targeting different stages of the mRNA translation, antimicrobial drugs can be changed if resistance develops to one or many of the drugs.
  • Diagram showing how the translation of the mRNA and the synthesis of proteins is made by ribosomes.

• The Incorporation of Nonstandard Amino Acids

  • Posttranslational modification (PTM) is the chemical modification of a protein after its translation.
  • After translation, the posttranslational modification of amino acids extends the range of functions of the protein by attaching it to other biochemical functional groups (such as acetate, phosphate, various lipids, and carbohydrates), changing the chemical nature of an amino acid (e.g., citrullination), or making structural changes (e.g., formation of disulfide bridges).
  • This amino acid is usually taken off during post-translational modification.
  • Non-standard amino acids that are found in proteins are formed by post-translational modification, which is modification after translation during protein synthesis.
  • Another example is the formation of hypusine in the translation initiation factor EIF5A through modification of a lysine residue.

• Control of Transcription in Archaea

  • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria.
  • The proteins that archaea, bacteria and eukaryotes share form a common core of cell function, relating mostly to transcription, translation, and nucleotide metabolism.
  • Transcription and translation in archaea resemble these processes in eukaryotes more than in bacteria, with the archaean RNA polymerase and ribosomes being very close to their equivalents in eukaryotes.

• Regulation by Biosynthetic Enzymes

  • It is based on the fact that, in bacteria, transcription and translation can and do proceed simultaneously.
  • When the RNA polymerase binds and transcribes the trp gene, the ribosome will start translating.
  • Therefore, the rest of the operon will be transcribed and translated, so that tryptophan can be produced.
  • Without domain 4, translation can continue regardless of the level of tryptophan.
  • The attenuator sequence has its codons translated into a leader peptide, but is not part of the trp operon gene sequence.