GroES
Encyclopedia
Heat shock 10 kDa protein 1 (Hsp10) also known as chaperonin 10 (cpn10) or early-pregnancy factor (EPF) is a protein
that in humans is encoded by the HSPE1 gene
. The homolog in E. coli
is GroES that is a chaperonin
which usually works in conjunction with GroEL
.
GroES exists as a ring-shaped oligomer
of between six to eight identical subunits, while the 60 kDa chaperonin (cpn60 - or groEL in bacteria) forms a structure
comprising 2 stacked rings, each ring containing 7 identical subunits
. These ring structures assemble by self-stimulation in the presence of Mg2+-ATP. The central cavity of the cylindrical cpn60 tetradecamer provides an isolated environment for protein folding
whilst cpn-10 binds to cpn-60 and synchronizes the release of the folded
protein in an Mg2+-ATP dependent manner. The binding of cpn10 to cpn60 inhibits
the weak ATPase activity of cpn60.
Escherichia coli
GroES has also been shown to bind ATP
cooperatively, and with an affinity comparable to that of GroEL. Each GroEL subunit contains three structurally distinct domains: an apical, an intermediate and an equatorial domain. The apical domain contains the binding site
s for both GroES and the unfolded protein substrate. The equatorial domain contains the ATP-binding site and most of the oligomeric contacts. The intermediate domain links the apical and equatorial domains
and transfers allosteric information between them. The GroEL oligomer is a tetradecamer, cylindrically shaped, that is organised in two heptameric rings stacked back to back. Each GroEL ring contains a central cavity, known as the `Anfinsen cage', that provides an isolated environment for protein folding. The identical 10 kDa subunits of GroES form a dome-like heptameric oligomer in solution. ATP binding to GroES may be important in charging the seven subunits of the interacting GroEL ring with ATP, to facilitate cooperative ATP binding and hydrolysis
for substrate protein release.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is encoded by the HSPE1 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...
. The homolog in E. coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
is GroES that is a chaperonin
Chaperonin
Chaperonins are proteins that fold and unfold other proteins. Newly made proteins usually must fold from a linear chain of amino acids into a three-dimensional form. Chaperonins belong to a large class of molecules that assist protein folding, called molecular chaperones...
which usually works in conjunction with GroEL
GroEL
GroEL belongs to the chaperonin family of molecular chaperones, and is found in a large number of bacteria. It is required for the proper folding of many proteins. To function properly, GroEL requires the lid-like cochaperonin protein complex GroES...
.
GroES exists as a ring-shaped oligomer
Oligomer
In chemistry, an oligomer is a molecule that consists of a few monomer units , in contrast to a polymer that, at least in principle, consists of an unlimited number of monomers. Dimers, trimers, and tetramers are oligomers. Many oils are oligomeric, such as liquid paraffin...
of between six to eight identical subunits, while the 60 kDa chaperonin (cpn60 - or groEL in bacteria) forms a structure
Secondary structure
In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids...
comprising 2 stacked rings, each ring containing 7 identical subunits
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
. These ring structures assemble by self-stimulation in the presence of Mg2+-ATP. The central cavity of the cylindrical cpn60 tetradecamer provides an isolated environment for protein folding
Protein folding
Protein folding is the process by which a protein structure assumes its functional shape or conformation. It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil....
whilst cpn-10 binds to cpn-60 and synchronizes the release of the folded
Protein folding
Protein folding is the process by which a protein structure assumes its functional shape or conformation. It is the physical process by which a polypeptide folds into its characteristic and functional three-dimensional structure from random coil....
protein in an Mg2+-ATP dependent manner. The binding of cpn10 to cpn60 inhibits
Enzyme inhibitor
An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...
the weak ATPase activity of cpn60.
Escherichia coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
GroES has also been shown to bind ATP
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
cooperatively, and with an affinity comparable to that of GroEL. Each GroEL subunit contains three structurally distinct domains: an apical, an intermediate and an equatorial domain. The apical domain contains the binding site
Binding site
In biochemistry, a binding site is a region on a protein, DNA, or RNA to which specific other molecules and ions—in this context collectively called ligands—form a chemical bond...
s for both GroES and the unfolded protein substrate. The equatorial domain contains the ATP-binding site and most of the oligomeric contacts. The intermediate domain links the apical and equatorial domains
Protein domain
A protein domain is a part of protein sequence and structure that can evolve, function, and exist independently of the rest of the protein chain. Each domain forms a compact three-dimensional structure and often can be independently stable and folded. Many proteins consist of several structural...
and transfers allosteric information between them. The GroEL oligomer is a tetradecamer, cylindrically shaped, that is organised in two heptameric rings stacked back to back. Each GroEL ring contains a central cavity, known as the `Anfinsen cage', that provides an isolated environment for protein folding. The identical 10 kDa subunits of GroES form a dome-like heptameric oligomer in solution. ATP binding to GroES may be important in charging the seven subunits of the interacting GroEL ring with ATP, to facilitate cooperative ATP binding and hydrolysis
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
for substrate protein release.