operons

Examples of operons in the following topics:

• The AraC Regulator

  • The L-arabinose operon, also called ara operon, encodes enzymes needed for the catabolism of arabinose to xylulose 5-phosphate.
  • The L-arabinose operon, also called ara operon, is a gene sequence encoding enzymes needed for the catabolism of arabinose to xylulose 5-phosphate, an intermediate of the pentose phosphate pathway.
  • The operon is found in Escherichia coli (E. coli).
  • The ara operon is regulated by the AraC protein.
  • This complex is needed for RNA polymerase to bind to the promoter and transcribe the ara operon.

• Regulation by Biosynthetic Enzymes

  • Attenuation (in genetics) is a proposed mechanism of control in some bacterial operons that results in premature termination of transcription.
  • Attenuation is an ancient regulatory system, prevalent in many bacterial species providing fast and sensitive regulation of gene operons and is commonly used to repress genes in the presence of their own product (or a downstream metabolite).
  • A high level of tryptophan will permit ribosomes to translate the attenuator sequence domains 1 and 2, allowing domains 3 and 4 to form a hairpin structure, which results in termination of transcription of the trp operon.
  • Therefore, the rest of the operon will be transcribed and translated, so that tryptophan can be produced.
  • The attenuator sequence has its codons translated into a leader peptide, but is not part of the trp operon gene sequence.

• Planctomycetes

  • A number of essential pathways are not organized as operons , which is unusual for bacteria.
  • In genetics, an operon is a functioning unit of genomic DNA containing a cluster of genes under the control of a single regulatory signal or promoter.

• Attenuation

  • Attenuation is a regulatory mechanism used in bacterial operons to ensure proper transcription and translation.
  • An example of attenuation is the tryptophan operon.

• Control of Transcription in Archaea

  • Other characteristic archaean features are the organization of genes of related function—such as enzymes that catalyze steps in the same metabolic pathway into novel operons, and large differences in tRNA genes and their aminoacyl tRNA synthetases.

• Nonribosomal Peptide Antibiotics

  • The NRPS genes for a certain peptide are usually organized in one operon in bacteria and in gene clusters in eukaryotes.

• Genetics and Regulation of N2 Fixation

  • Nitrogen fixation is regulated by nif regulon, which is a set of seven operons which includes 17 nif genes.

• Archaeal Gene Regulation

  • Other characteristic archaean features are the organization of genes of related function—such as enzymes that catalyze steps in the same metabolic pathway into novel operons, and large differences in tRNA genes and their aminoacyl tRNA synthetases.

• Selective and Differential Media

• Two-Component Regulatory Systems

  • The KdpD sensor kinase proteins regulate the kdpFABC operon responsible for potassium transport in bacteria including E. coli and Clostridium acetobutylicum.