TrpE

Definition

trpE is a gene that encodes the enzyme anthranilate synthase, which is critical in the biosynthesis of the amino acid tryptophan in prokaryotic organisms. It is part of the trp operon, a cluster of genes that collectively regulate tryptophan production and help the organism adapt to varying nutrient availability. This gene's regulation plays a vital role in prokaryotic gene regulation by responding to intracellular tryptophan levels.

5 Must Know Facts For Your Next Test

1. trpE is the first gene in the trp operon and is essential for the initial step in tryptophan biosynthesis.
2. The expression of trpE is tightly regulated by the availability of tryptophan; when levels are sufficient, transcription is repressed.
3. Mutations in trpE can lead to auxotrophy for tryptophan, meaning that the organism cannot synthesize it and requires it from external sources.
4. The trp operon utilizes a leader sequence that allows for attenuation, a mechanism that fine-tunes gene expression based on tryptophan levels.
5. trpE and its associated genes are examples of how prokaryotes efficiently manage resources and respond to environmental changes through gene regulation.

Review Questions

• How does trpE contribute to the regulation of the trp operon in response to tryptophan levels?
  • trpE plays a crucial role in the regulation of the trp operon by encoding an enzyme involved in tryptophan biosynthesis. When tryptophan levels are high, a repressor protein binds to the operator region of the trp operon, inhibiting transcription of trpE and the other genes in the operon. This feedback mechanism prevents unnecessary production of tryptophan, allowing prokaryotes to conserve energy and resources.
• Explain how feedback inhibition affects the activity of trpE and its role in metabolic pathways.
  • Feedback inhibition directly impacts the activity of trpE by regulating its expression based on tryptophan availability. When enough tryptophan is present, it binds to the repressor protein, which then attaches to the operator site of the trp operon. This prevents transcription of trpE and other genes necessary for tryptophan production, ensuring that resources are not wasted on synthesizing an already abundant amino acid. Such regulation exemplifies how metabolic pathways are fine-tuned to meet cellular needs.
• Evaluate the significance of attenuation mechanisms in regulating trpE and overall tryptophan biosynthesis within prokaryotes.
  • Attenuation mechanisms are significant because they provide an additional layer of regulation for genes like trpE, allowing prokaryotes to rapidly respond to fluctuating tryptophan levels. By utilizing a leader sequence that can form different structures based on amino acid availability, cells can efficiently regulate whether transcription continues or terminates prematurely. This not only conserves energy by preventing unnecessary synthesis but also highlights the complexity of gene regulation in prokaryotes, showcasing their adaptability to environmental changes.

Related terms

trp Operon: A group of genes in bacteria that are co-regulated and involved in the biosynthesis of tryptophan, including trpE.

Repressor Protein: A protein that binds to specific DNA sequences to inhibit transcription of target genes, such as the trpE gene when tryptophan levels are high.

Feedback Inhibition: A regulatory mechanism where the end product of a metabolic pathway inhibits an upstream process, such as tryptophan inhibiting its own synthesis by affecting trpE expression.