GlmS glucosamine-6-phosphate activated ribozyme
Encyclopedia
The Glucosamine-6-phosphate activated ribozyme ( glmS ribozyme) is an RNA
structure that is both a ribozyme
, since it catalyzes
a chemical reaction, and a riboswitch
, since it regulates genes in response to concentrations of a metabolite
.
It was originally identified using bioinformatics
in the 5' untranslated region
s of glmS gene
s.
The glmS gene catalyzes the production of glucosamine-6-phosphate (GlcN6P), and the glmS ribozyme is dependent on GlcN6P to achieve catalysis of its own cleavage. This cleavage leads to the degradation of the mRNA that contains the ribozyme, and ultimately lowers production of the GlmS enzyme
, encoded by the glmS gene. The GlmS enzyme catalyzes the reaction to synthesize GlcN6P, so it is not required when GlcN6P levels are already high. When GlcN6P levels are low, the ribozyme does not cleave, allowing production of the GlmS enzyme, and ultimately more GlcN6P. In fact, GlcN6P is a cofactor for the cleavage reaction, as it directly participates in the chemical reaction.
. The RNA adopts a double pseudoknot
ted structure. The cofactor is bound in a solvent-accessible pocket and the structure suggests that the amine group of GlcN6P is involved in the catalytic process.
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
structure that is both a ribozyme
Ribozyme
A ribozyme is an RNA molecule with a well defined tertiary structure that enables it to catalyze a chemical reaction. Ribozyme means ribonucleic acid enzyme. It may also be called an RNA enzyme or catalytic RNA. Many natural ribozymes catalyze either the hydrolysis of one of their own...
, since it catalyzes
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....
a chemical reaction, and a riboswitch
Riboswitch
In molecular biology, a riboswitch is a part of an mRNA molecule that can directly bind a small target molecule, and whose binding of the target affects the gene's activity. Thus, an mRNA that contains a riboswitch is directly involved in regulating its own activity, in response to the...
, since it regulates genes in response to concentrations of a metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
.
It was originally identified using bioinformatics
Bioinformatics
Bioinformatics is the application of computer science and information technology to the field of biology and medicine. Bioinformatics deals with algorithms, databases and information systems, web technologies, artificial intelligence and soft computing, information and computation theory, software...
in the 5' untranslated region
Five prime untranslated region
A messenger ribonucleic acid molecule codes for a protein through translation. The mRNA also contains regions that are not translated: in eukaryotes these include the 5' untranslated region, 3' untranslated region, 5' cap and poly-A tail....
s of glmS gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s.
The glmS gene catalyzes the production of glucosamine-6-phosphate (GlcN6P), and the glmS ribozyme is dependent on GlcN6P to achieve catalysis of its own cleavage. This cleavage leads to the degradation of the mRNA that contains the ribozyme, and ultimately lowers production of the GlmS enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
, encoded by the glmS gene. The GlmS enzyme catalyzes the reaction to synthesize GlcN6P, so it is not required when GlcN6P levels are already high. When GlcN6P levels are low, the ribozyme does not cleave, allowing production of the GlmS enzyme, and ultimately more GlcN6P. In fact, GlcN6P is a cofactor for the cleavage reaction, as it directly participates in the chemical reaction.
Structure
The structure of the GlmS ribozyme has been determined by X-ray crystallographyX-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
. The RNA adopts a double pseudoknot
Pseudoknot
A pseudoknot is a nucleic acid secondary structure containing at least two stem-loop structures in which half of one stem is intercalated between the two halves of another stem. The pseudoknot was first recognized in the turnip yellow mosaic virus in 1982...
ted structure. The cofactor is bound in a solvent-accessible pocket and the structure suggests that the amine group of GlcN6P is involved in the catalytic process.