Related Experiment Video

Updated: Aug 13, 2026

Overexpression and Purification of Human Cis-prenyltransferase in Escherichia coli
07:35

Overexpression and Purification of Human Cis-prenyltransferase in Escherichia coli

Published on: August 3, 2017

Suppression of defects in cyclic adenosine 3',5'-monophosphate metabolism in Escherichia coli

J K Alexander

    Journal of Bacteriology
    |October 1, 1980
    PubMed

    Insights

    A suppressor mutation (sup) in Escherichia coli enhances growth on various sugars and increases enzyme activity. This sup mutation alters the cyclic adenosine monophosphate receptor protein, affecting its response to cyclic nucleotides.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Genetics

    Background:

    • Escherichia coli growth and metabolism are regulated by various factors, including nutrient availability and signaling molecules.
    • The cyclic adenosine monophosphate (cAMP) receptor protein (CRP) plays a crucial role in regulating gene expression in response to cAMP levels.

    Purpose of the Study:

    • To investigate the effect of a suppressor mutation (sup) on the phenotype of Escherichia coli.
    • To elucidate the mechanism by which the sup mutation influences bacterial growth and enzyme activity.
    • To characterize the interaction of the sup mutation with the cAMP signaling pathway.

    Main Methods:

    • Phenotypic analysis of Escherichia coli strains with and without the sup mutation.
    • Enzyme activity assays (beta-galactosidase, tryptophanase).
    • Growth studies in various media.
    • Investigation of responses to cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP).

    Main Results:

    • The sup mutation enhanced growth on glycerol, maltose, melibiose, and succinate.
    • Increased beta-galactosidase and tryptophanase activity was observed in the presence of sup.
    • sup partially suppressed the cya phenotype (adenylate cyclase deficiency).
    • cGMP significantly increased beta-galactosidase activity and restored growth on multiple sugars in a cya mutant.
    • The sup mutation appears to be located in the crp locus, suggesting an altered cAMP receptor protein.

    Conclusions:

    • The sup mutation in Escherichia coli leads to a modified cAMP receptor protein.
    • This altered protein exhibits increased affinity for cAMP and can be activated by cGMP.
    • These findings provide insights into the regulation of bacterial metabolism and the role of cyclic nucleotides in gene expression.

    More Related Videos

    Producing Gene Deletions in Escherichia coli by P1 Transduction with Excisable Antibiotic Resistance Cassettes08:13

    Producing Gene Deletions in Escherichia coli by P1 Transduction with Excisable Antibiotic Resistance Cassettes

    Published on: September 1, 2018

    Site-Directed Mutagenesis for In Vitro and In Vivo Experiments Exemplified with RNA Interactions in Escherichia Coli07:04

    Site-Directed Mutagenesis for In Vitro and In Vivo Experiments Exemplified with RNA Interactions in Escherichia Coli

    Published on: February 5, 2019

    Related Concept Videos

    Allosteric Proteins-ATCase01:19

    Allosteric Proteins-ATCase

    Binding sites linkages can regulate a protein's function.  For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
    Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to  N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
    GPCRs Regulate Adenylyl Cylase Activity01:09

    GPCRs Regulate Adenylyl Cylase Activity

    Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
    Two...
    Amino Acid Catabolism01:18

    Amino Acid Catabolism

    Microorganisms rely on proteins as an essential carbon and energy source, particularly in environments with limited polysaccharides or lipids. However, proteins are too large to cross the plasma membrane unaided, necessitating enzymatic degradation. Microbes secrete extracellular proteases and peptidases that hydrolyze proteins into peptides, which can then be transported across the membrane. Once inside the cell, intracellular proteases degrade these peptides into free amino acids, which...
    Biosynthesis of Nucleic Acids01:28

    Biosynthesis of Nucleic Acids

    Nucleic acid biosynthesis is a fundamental biochemical process that produces the purine and pyrimidine nucleotides essential for DNA and RNA synthesis. This pathway maintains a balanced nucleotide pool, preventing imbalances that could jeopardize genetic integrity and cellular function. Given the crucial role of nucleotides, their synthesis is tightly regulated to ensure proper cellular homeostasis.Purine BiosynthesisThe biosynthesis of purine nucleotides begins with ribose-5-phosphate, a...
    Stringent Response in E. coli01:23

    Stringent Response in E. coli

    Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
    Inhibitors of Bacterial Protein Synthesis01:25

    Inhibitors of Bacterial Protein Synthesis

    Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...