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Related Concept Videos

Operons02:09

Operons

44.2K
Prokaryotes can control gene expression through operons—DNA sequences consisting of regulatory elements and clustered, functionally related protein-coding genes. Operons use a single promoter sequence to initiate transcription of a gene cluster (i.e., a group of structural genes) into a single mRNA molecule. The terminator sequence ends transcription. An operator sequence, located between the promoter and structural genes, prohibits the operon’s transcriptional activity if bound by...
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Eukaryotic Transcription Inhibitors01:52

Eukaryotic Transcription Inhibitors

9.1K
Certain biochemical processes, such as embryonic development and cell growth regulation, depend on the repression of specific genes. DNA binding proteins known as eukaryotic transcription inhibitors regulate the repression of gene expression in eukaryotes. The presence of these inhibitors at the required location and time in the cell is triggered by the presence of hormones and additional signals from other cells.
Eukaryotic transcription inhibitors usually contain two distinct domains, a...
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Regulation of Expression at Multiple Steps01:23

Regulation of Expression at Multiple Steps

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The gene expression in cells is regulated at different stages: (i) transcription, (ii) RNA processing, (iii) RNA localization, and (iv) translation. Transcriptional regulation is mediated by regulatory proteins such as transcription factors, activators, or repressors—these control gene expression by initiating or inhibiting the transcription of genes. Once a precursor or pre-mRNA is produced, it undergoes post-transcriptional modification, including 5' capping, splicing, and the...
1.4K
Operon Model01:23

Operon Model

2.6K
The operon model represents a fundamental mechanism of gene regulation in prokaryotes, enabling coordinated expression of genes involved in related metabolic or functional pathways. Operons consist of structural genes, a promoter, and an operator, with transcription regulated by repressors, activators, and small effector molecules.Structure and Function of OperonsAn operon is a cluster of structural genes transcribed together under the control of a single promoter. The promoter region...
2.6K
Inducible Operons: lac Operon01:25

Inducible Operons: lac Operon

3.1K
The lac operon in Escherichia coli is a model for understanding inducible gene regulation and metabolic flexibility. It integrates local control by lactose and global regulation through catabolite repression, enabling E. coli to preferentially metabolize glucose when available and switch to lactose utilization when glucose is scarce.Structure and Function of the lac OperonThe lac operon contains three structural genes: lacZ (β-galactosidase), lacY (lactose permease), and lacA...
3.1K
Transcriptional Regulation: Riboswitches01:23

Transcriptional Regulation: Riboswitches

1.2K
Riboswitches are RNA elements that regulate gene expression by altering their secondary structures in response to specific effector molecules. These elements, located in the leader regions of certain mRNAs, act as transcriptional regulators by toggling between alternative conformations to control downstream gene expression. Riboswitch-mediated regulation is a precise mechanism for modulating biosynthetic pathways, as exemplified by the riboflavin biosynthesis pathway in Bacillus...
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Related Experiment Video

Updated: May 6, 2026

In vivo Application of the REMOTE-control System for the Manipulation of Endogenous Gene Expression
08:54

In vivo Application of the REMOTE-control System for the Manipulation of Endogenous Gene Expression

Published on: March 29, 2019

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Regulatory revolution: evolving the "anti-LacI" repressor.

Christopher J Marx1

  • 1Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA. cmarx@oeb.harvard.edu

Cell
|August 6, 2011
PubMed
Summary

Researchers evolved the lac repressor (LacI) to reverse its regulatory logic. This created an "anti-LacI" that represses gene transcription upon inducer binding, demonstrating novel regulatory evolution.

Area of Science:

  • Molecular Biology
  • Evolutionary Biology
  • Genetics

Background:

  • Adaptation often involves changes in gene expression, but the direct observation of new regulatory logic emerging has been limited.
  • The lac repressor (LacI) is a well-studied protein that normally represses the lac operon in the absence of its inducer, lactose.

Discussion:

  • Poelwijk et al. engineered a novel regulatory mechanism by evolving the LacI protein.
  • The study directly observed the emergence of reversed regulatory logic in a biological system.
  • This engineered 'anti-LacI' protein exhibits a fundamentally altered interaction with its inducer molecule.

Key Insights:

  • The lac repressor (LacI) was successfully evolved to exhibit reversed regulatory logic.
  • The modified protein, termed 'anti-LacI', now represses transcription when its specific inducer is present.

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  • This work provides direct experimental evidence for the de novo evolution of gene regulatory logic.

    • Outlook:

    • This study opens avenues for engineering novel gene regulatory circuits with predictable functions.
    • Understanding the evolution of regulatory logic can inform synthetic biology and the design of complex genetic systems.
    • Further research could explore the broader applicability of evolving existing regulatory proteins to achieve new functions.