Lac repressor: Difference between revisions

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Repressors are proteins that inhibit the expression of [http://en.wikipedia.org/wiki/Gene genes]; that is, they inhibit the transcription of [http://en.wikipedia.org/wiki/Messenger_rna messenger RNA] from their target genes. Each repressor targets a specific co-regulated group of genes by recognizing a specific sequence of DNA, called the ''operator'' in [http://en.wikipedia.org/wiki/Bacteria bacteria]. Repressor proteins are coded for by ''regulatory'' genes.

The lactose ("lac") repressor controls the expression of bacterial enzymes involved in the metabolism of of the sugar lactose. When the lac repressor binds lactose, it changes to an inactive conformation that cannot repress the production of these enzymes. Thus, the enzymes needed to use lactose are made only when lactose is available. The lac repressor, and the group of genes it controls, which is called an [http://en.wikipedia.org/wiki/Operon operon], were the first such gene regulatory system to be discovered. The operon was described in 1960<ref>L'opéron: groupe de gènes à expression coordonée par un opérateur. [Operon: a group of genes with the expression coordinated by an operator.] C R Hebd Seances Acad Sci., 250:1727-9, 1960. [http://www.ncbi.nlm.nih.gov/pubmed/14406329 PubMed 14406329]</ref> by François Jacob ''et al.'', who also correctly proposed the general mechanism of regulation by the lac repressor. The [http://nobelprize.org/nobel_prizes/medicine/laureates/1965/ 1965 Nobel Prize in Physiology or Medicine] was awarded to François Jacob, André Lwoff, and Jacques Monod "for their discoveries concerning genetic control of enzyme and virus synthesis".

The '''lactose ("lac") repressor''' controls the expression of bacterial enzymes involved in the metabolism of of the sugar lactose. When the lac repressor binds lactose, it changes to an inactive conformation that cannot repress the production of these enzymes. Thus, the enzymes needed to use lactose are made only when lactose is available. The lac repressor, and the group of genes it controls, which is called an [http://en.wikipedia.org/wiki/Operon operon], were the first such gene regulatory system to be discovered. The operon was described in 1960<ref>L'opéron: groupe de gènes à expression coordonée par un opérateur. [Operon: a group of genes with the expression coordinated by an operator.] C R Hebd Seances Acad Sci., 250:1727-9, 1960. [http://www.ncbi.nlm.nih.gov/pubmed/14406329 PubMed 14406329]</ref> by François Jacob ''et al.'', who also correctly proposed the general mechanism of regulation by the lac repressor. The [http://nobelprize.org/nobel_prizes/medicine/laureates/1965/ 1965 Nobel Prize in Physiology or Medicine] was awarded to François Jacob, André Lwoff, and Jacques Monod "for their discoveries concerning genetic control of enzyme and virus synthesis".

For a general introduction to the lac repressor, please see David Goodsell's [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb39_1.html Introduction to the lac repressor] in his series [[Molecule of the Month]], and the article in Wikipedia on the [http://en.wikipedia.org/wiki/Lac_repressor lac repressor]. Mitchell Lewis published a detailed review in 2005<ref name='lewis'>The lac repressor. Lewis, M. C R Biol. 328:521-48, 2005. [http://www.ncbi.nlm.nih.gov/pubmed/15950160 PubMed 15950160]</ref>.

Lac repressor: Difference between revisions

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 Repressors are proteins that inhibit the expression of [http://en.wikipedia.org/wiki/Gene genes]; that is, they inhibit the transcription of [http://en.wikipedia.org/wiki/Messenger_rna messenger RNA] from their target genes. Each repressor targets a specific co-regulated group of genes by recognizing a specific sequence of DNA, called the ''operator'' in [http://en.wikipedia.org/wiki/Bacteria bacteria]. Repressor proteins are coded for by ''regulatory'' genes.
-The lactose ("lac") repressor controls the expression of bacterial enzymes involved in the metabolism of of the sugar lactose. When the lac repressor binds lactose, it changes to an inactive conformation that cannot repress the production of these enzymes. Thus, the enzymes needed to use lactose are made only when lactose is available. The lac repressor, and the group of genes it controls, which is called an [http://en.wikipedia.org/wiki/Operon operon], were the first such gene regulatory system to be discovered. The operon was described in 1960<ref>L'opéron: groupe de gènes à expression coordonée par un opérateur. [Operon: a group of genes with the expression coordinated by an operator.] C R Hebd Seances Acad Sci., 250:1727-9, 1960. [http://www.ncbi.nlm.nih.gov/pubmed/14406329 PubMed 14406329]</ref> by François Jacob ''et al.'', who also correctly proposed the general mechanism of regulation by the lac repressor. The [http://nobelprize.org/nobel_prizes/medicine/laureates/1965/ 1965 Nobel Prize in Physiology or Medicine] was awarded to François Jacob, André Lwoff, and Jacques Monod "for their discoveries concerning genetic control of enzyme and virus synthesis".
+The '''lactose ("lac") repressor''' controls the expression of bacterial enzymes involved in the metabolism of of the sugar lactose. When the lac repressor binds lactose, it changes to an inactive conformation that cannot repress the production of these enzymes. Thus, the enzymes needed to use lactose are made only when lactose is available. The lac repressor, and the group of genes it controls, which is called an [http://en.wikipedia.org/wiki/Operon operon], were the first such gene regulatory system to be discovered. The operon was described in 1960<ref>L'opéron: groupe de gènes à expression coordonée par un opérateur. [Operon: a group of genes with the expression coordinated by an operator.] C R Hebd Seances Acad Sci., 250:1727-9, 1960. [http://www.ncbi.nlm.nih.gov/pubmed/14406329 PubMed 14406329]</ref> by François Jacob ''et al.'', who also correctly proposed the general mechanism of regulation by the lac repressor. The [http://nobelprize.org/nobel_prizes/medicine/laureates/1965/ 1965 Nobel Prize in Physiology or Medicine] was awarded to François Jacob, André Lwoff, and Jacques Monod "for their discoveries concerning genetic control of enzyme and virus synthesis".
 For a general introduction to the lac repressor, please see David Goodsell's [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb39_1.html Introduction to the lac repressor] in his series [[Molecule of the Month]], and the article in Wikipedia on the [http://en.wikipedia.org/wiki/Lac_repressor lac repressor]. Mitchell Lewis published a detailed review in 2005<ref name='lewis'>The lac repressor. Lewis, M. C R Biol. 328:521-48, 2005. [http://www.ncbi.nlm.nih.gov/pubmed/15950160 PubMed 15950160]</ref>.