Related Experiment Video
Updated: Aug 11, 2026
06:05
Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins
Published on: September 30, 2014
Repressor gene, blaI, for Bacillus licheniformis 749 beta-lactamase
FEBS Letters
|August 31, 1987
Summary
The Bacillus licheniformis beta-lactamase repressor gene (blaI) functions in E. coli but lacks induction. Full repression requires interaction with both the repressor and promoter regions.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The beta-lactamase repressor gene (blaI) from Bacillus licheniformis 749 was investigated for its function in Escherichia coli.
- Previous studies suggested blaI regulates beta-lactamase production.
Purpose of the Study:
- To characterize the function and regulation of the beta-lactamase repressor gene (blaI) from Bacillus licheniformis 749.
- To determine the interaction sites of the BlaI repressor with its target DNA sequence.
Main Methods:
- Cloning of the blaI gene and associated regulatory regions into plasmids in E. coli.
- Analysis of beta-lactamase induction in response to beta-lactam addition.
- Characterization of the BlaI protein structure and potential interactions.
Main Results:
- The cloned blaI gene was functional in E. coli, producing a repressor protein.
- However, beta-lactam induction of beta-lactamase activity was not observed.
- The blaI gene is located upstream of the beta-lactamase structural gene (blaP).
- Repression appears to involve interaction with both the blaI gene and the promoter region between blaI and blaP.
- BlaI is a hydrophilic protein with structural similarities to repressors in Gram-negative bacteria.
Conclusions:
- The BlaI repressor protein is functional in E. coli, but the induction mechanism differs from that in B. licheniformis.
- Full repression of beta-lactamase requires interaction at multiple promoter sites.
- BlaI represents a novel class of Gram-negative-like repressors.
More Related Videos
Related Concept Videos
02:09Operons
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 a repressor...
01:58Prokaryotic Transcriptional Activators and Repressors
The organization of prokaryotic genes in their genome is notably different from that of eukaryotes. Prokaryotic genes are organized, such that the genes for proteins involved in the same biochemical process or function are located together in groups. This group of genes, along with their regulatory elements, are collectively known as an operon. The functional genes in an operon are transcribed together to give a single strand of mRNA known as polycistronic mRNA.
Transcription of prokaryotic...
Transcription of prokaryotic...
01:58Prokaryotic Transcriptional Activators and Repressors
The organization of prokaryotic genes in their genome is notably different from that of eukaryotes. Prokaryotic genes are organized, such that the genes for proteins involved in the same biochemical process or function are located together in groups. This group of genes, along with their regulatory elements, are collectively known as an operon. The functional genes in an operon are transcribed together to give a single strand of mRNA known as polycistronic mRNA.
Transcription of prokaryotic...
Transcription of prokaryotic...
01:23Operon Model
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...
01:25Inducible Operons: lac Operon
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 (thiogalactoside...
01:21Repressible Operon: trp Operon
The trp operon in Escherichia coli exemplifies a repressible operon. It regulates the synthesis of tryptophan through repressor-mediated transcriptional control and attenuation. This dual regulatory mechanism ensures tryptophan biosynthesis occurs only when needed, conserving cellular resources.Structure of the trp OperonThe trp operon consists of five structural genes (trpE, trpD, trpC, trpB, and trpA) that encode enzymes for tryptophan biosynthesis. These genes are transcribed as a single...