Caspase 3
Encyclopedia
Caspase 3 is a caspase
protein that interacts with caspase 8
and caspase 9. It is encoded by the CASP3 gene. CASP3 orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts.
The CASP3 protein
is a member of the cysteine-aspartic acid protease (caspase
) family. Sequential activation of caspases plays a central role in the execution-phase of cell apoptosis
. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active enzyme
. This protein cleaves and activates caspases 6 and 7; and the protein itself is processed and activated by caspases 8, 9, and 10. It is the predominant caspase involved in the cleavage of amyloid-beta 4A precursor protein, which is associated with neuronal death in Alzheimer's disease
. Alternative splicing of this gene results in two transcript variants that encode the same protein.
Caspase-3 shares many of the typical characteristics common to all currently-known caspases. For example, its active site contains a cysteine
residue (Cys-285) and histidine
residue (His-237) that stabilize the peptide bond
cleavage of a protein sequence to the carboxy-terminal side of an aspartic acid
when it is part of a particular 4-amino acid sequence. This specificity allows caspases to be incredibly selective, with a 20,000-fold preference for aspartic acid over glutamic acid
. A key feature of caspases in the cell is that they are present as zymogens, termed procaspases, which are inactive until a biochemical change causes their activation. Each procaspase has an N-terminal large subunit of about 20 kDa followed by a smaller subunit of about 10 kDa, called p20 and p10, respectively.
residues. Caspase 3 and caspase 7
share similar substrate specificity by recognizing tetra-peptide motif Asp-x-x-Asp. The C-terminal Asp is absolutely required while variations at other three positions can be tolerated. Caspase substrate specificity has been widely used in caspase based inhibitor
and drug design.
ring of His-237. His-237 stabilizes the carbonyl
group of the key aspartate residue, while Cys-285 attacks to ultimately cleave the peptide bond. Cys-285 and Gly-238 also function to stabilize the tetrahedral transition state
of the substrate-enzyme complex through hydrogen bonding. In vitro
, caspase-3 has been found to prefer the peptide sequence DEVDG (Asp-Glu-Val-Asp-Gly) with cleavage occurring on the carboxy side of the second aspartic acid residue (between D and G). Caspase-3 is active over a broad pH
range that is slightly higher (more basic) than many of the other executioner caspases. This broad range indicates that caspase-3 will be fully active under normal and apoptotic cell conditions.
from the mitochondria in combination with caspase-9
, apoptosis-activating factor 1 (Apaf-1), and ATP
process procaspase-3. These molecules are sufficient to activate caspase-3 in vitro, but other regulatory proteins are necessary in vivo
.
Mangosteen (Garcinia Mangostana) extract has been shown to inhibit the activation of caspase 3 in B-amyloid treated human neuronal cells.
, and ML-IAP. XIAP binds and inhibits initiator caspase-9, which is directly involved in the activation of executioner caspase-3. During the caspase cascade, however, caspase-3 functions to inhibit XIAP activity by cleaving caspase-9 at a specific site, preventing XIAP from being able to bind to inhibit caspase-9 activity.
with:
development as well as its typical role in apoptosis, where it is responsible for chromatin
condensation and DNA
fragmentation. Elevated levels of a fragment of Caspase-3, p17, in the bloodstream is a sign of a recent myocardial infarction
. It is now being shown that caspase-3 may play a role in embryonic and hematopoietic stem cell
differentiation.
Caspase
Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis , necrosis, and inflammation....
protein that interacts with caspase 8
Caspase 8
Caspase 8 is a caspase protein, encoded by the CASP8 gene. It most likely acts upon caspase 3.CASP8 orthologs have been identified in numerous mammals for which complete genome data are available...
and caspase 9. It is encoded by the CASP3 gene. CASP3 orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts.
The CASP3 protein
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...
is a member of the cysteine-aspartic acid protease (caspase
Caspase
Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis , necrosis, and inflammation....
) family. Sequential activation of caspases plays a central role in the execution-phase of cell apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active 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...
. This protein cleaves and activates caspases 6 and 7; and the protein itself is processed and activated by caspases 8, 9, and 10. It is the predominant caspase involved in the cleavage of amyloid-beta 4A precursor protein, which is associated with neuronal death in Alzheimer's disease
Alzheimer's disease
Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
. Alternative splicing of this gene results in two transcript variants that encode the same protein.
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Caspase-3 shares many of the typical characteristics common to all currently-known caspases. For example, its active site contains a cysteine
Cysteine
Cysteine is an α-amino acid with the chemical formula HO2CCHCH2SH. It is a non-essential amino acid, which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, which is polar and thus cysteine is usually classified as a hydrophilic amino acid...
residue (Cys-285) and histidine
Histidine
Histidine Histidine, an essential amino acid, has a positively charged imidazole functional group. It is one of the 22 proteinogenic amino acids. Its codons are CAU and CAC. Histidine was first isolated by German physician Albrecht Kossel in 1896. Histidine is an essential amino acid in humans...
residue (His-237) that stabilize the peptide bond
Peptide bond
This article is about the peptide link found within biological molecules, such as proteins. A similar article for synthetic molecules is being created...
cleavage of a protein sequence to the carboxy-terminal side of an aspartic acid
Aspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
when it is part of a particular 4-amino acid sequence. This specificity allows caspases to be incredibly selective, with a 20,000-fold preference for aspartic acid over glutamic acid
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
. A key feature of caspases in the cell is that they are present as zymogens, termed procaspases, which are inactive until a biochemical change causes their activation. Each procaspase has an N-terminal large subunit of about 20 kDa followed by a smaller subunit of about 10 kDa, called p20 and p10, respectively.
Substrate specificity
Under normal circumstances, caspases recognize tetra-peptide sequences on their substrates and hydrolyze peptide bonds after aspartic acidAspartic acid
Aspartic acid is an α-amino acid with the chemical formula HOOCCHCH2COOH. The carboxylate anion, salt, or ester of aspartic acid is known as aspartate. The L-isomer of aspartate is one of the 20 proteinogenic amino acids, i.e., the building blocks of proteins...
residues. Caspase 3 and caspase 7
Caspase 7
Caspase-7, apoptosis-related cysteine peptidase, also known as CASP7, is a human protein encoded by the CASP7 gene.CASP7 orthologs have been identified in nearly all mammals for which complete genome data are available...
share similar substrate specificity by recognizing tetra-peptide motif Asp-x-x-Asp. The C-terminal Asp is absolutely required while variations at other three positions can be tolerated. Caspase substrate specificity has been widely used in caspase based inhibitor
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...
and drug design.
Structure
Caspase-3, in particular, (also known as CPP32/Yama/apopain) is formed from a 32 kDa zymogen that is cleaved into 17 kDa and 12 kDa subunits. When the procaspase is cleaved at a particular residue, the active heterotetramer can then be formed by hydrophobic interactions, causing four anti-parallel beta-sheets from p17 and two from p12 to come together two make a heterodimer, which in turn interacts with another heterodimer to form the full 12-stranded beta-sheet structure surrounded by alpha-helices that is unique to caspases. When the heterodimers align head-to-tail with each other, an active site is positioned at each end of the molecule formed by residues from both participating subunits, though the necessary Cys-285 and His-237 residues are found on the p17 (larger) subunit.Mechanism
The catalytic site of caspase-3 involves the sulfohydryl group of Cys-285 and the imidazoleImidazole
Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and is classified as an alkaloid. Imidazole refers to the parent compound, whereas imidazoles are a class of heterocycles with similar ring structure, but varying substituents...
ring of His-237. His-237 stabilizes the carbonyl
Carbonyl
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups....
group of the key aspartate residue, while Cys-285 attacks to ultimately cleave the peptide bond. Cys-285 and Gly-238 also function to stabilize the tetrahedral transition state
Transition state
The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest energy along this reaction coordinate. At this point, assuming a perfectly irreversible reaction, colliding reactant molecules will always...
of the substrate-enzyme complex through hydrogen bonding. In vitro
In vitro
In vitro refers to studies in experimental biology that are conducted using components of an organism that have been isolated from their usual biological context in order to permit a more detailed or more convenient analysis than can be done with whole organisms. Colloquially, these experiments...
, caspase-3 has been found to prefer the peptide sequence DEVDG (Asp-Glu-Val-Asp-Gly) with cleavage occurring on the carboxy side of the second aspartic acid residue (between D and G). Caspase-3 is active over a broad pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
range that is slightly higher (more basic) than many of the other executioner caspases. This broad range indicates that caspase-3 will be fully active under normal and apoptotic cell conditions.
Activation
Caspase-3 is activated in the apoptotic cell both by extrinsic (death ligand) and intrinsic (mitochondrial) pathways. The zymogen feature of caspase-3 is necessary because if unregulated, caspase activity would kill cells indiscriminately. As an executioner caspase, the caspase-3 zymogen has virtually no activity until it is cleaved by an initiator caspase after apoptotic signaling events have occurred. One such signaling event is the introduction of granzyme B, which can activate initiator caspases, into cells targeted for apoptosis by killer T cells. This extrinsic activation then triggers the hallmark caspase cascade characteristic of the apoptotic pathway, in which caspase-3 plays a dominant role. In intrinsic activation, cytochrome cCytochrome c
The Cytochrome complex, or cyt c is a small heme protein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins. Cytochrome c is a highly soluble protein, unlike other cytochromes, with a solubility of about 100 g/L and is an...
from the mitochondria in combination with caspase-9
Caspase-9
Caspase-9 is an initiator caspase, encoded by the CASP9 gene.CASP9 orthologs have been identified in all mammals for which complete genome data are available. Unique orthologs are also present in lizards, lissamphibians, and teleosts....
, apoptosis-activating factor 1 (Apaf-1), and 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...
process procaspase-3. These molecules are sufficient to activate caspase-3 in vitro, but other regulatory proteins are necessary in vivo
In vivo
In vivo is experimentation using a whole, living organism as opposed to a partial or dead organism, or an in vitro controlled environment. Animal testing and clinical trials are two forms of in vivo research...
.
Mangosteen (Garcinia Mangostana) extract has been shown to inhibit the activation of caspase 3 in B-amyloid treated human neuronal cells.
Inhibition
One means of caspase inhibition is through the IAP (inhibitor of apoptosis) protein family, which includes c-IAP1, c-IAP2, XIAPXIAP
X-linked inhibitor of apoptosis protein also known as inhibitor of apoptosis protein 3 and baculoviral IAP repeat-containing protein 4 is a protein that in humans is encoded by the XIAP gene....
, and ML-IAP. XIAP binds and inhibits initiator caspase-9, which is directly involved in the activation of executioner caspase-3. During the caspase cascade, however, caspase-3 functions to inhibit XIAP activity by cleaving caspase-9 at a specific site, preventing XIAP from being able to bind to inhibit caspase-9 activity.
Interactions
Caspase 3 has been shown to interactProtein-protein interaction
Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...
with:
- CASP8Caspase 8Caspase 8 is a caspase protein, encoded by the CASP8 gene. It most likely acts upon caspase 3.CASP8 orthologs have been identified in numerous mammals for which complete genome data are available...
, - CFLARCFLARCASP8 and FADD-like apoptosis regulator is a protein that in humans is encoded by the CFLAR gene. Also called FLICE-like inhibitory protein .-Further reading:...
, - DCCDeleted in Colorectal CancerDeleted in Colorectal Carcinoma, also known as DCC, is a protein which in humans is encoded by the DCC gene. DCC has long been implicated in colorectal cancer. While the official, full name of this gene is Deleted in Colorectal Carcinoma, it is almost universally called Deleted in Colorectal Cancer...
, - GroELGroELGroEL 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...
, - HCLS1HCLS1Hematopoietic lineage cell-specific protein is a protein that in humans is encoded by the HCLS1 gene.-Interactions:HCLS1 has been shown to interact with Caspase 3.-Further reading:...
, - SurvivinSurvivinSurvivin, also called baculoviral inhibitor of apoptosis repeat-containing 5 or BIRC5, is a protein that, in humans, is encoded by the BIRC5 gene....
, - TRAF3TRAF3TNF receptor-associated factor 3 is a protein that in humans is encoded by the TRAF3 gene.-Interactions:TRAF3 has been shown to interact with CD30, CD27, Lymphotoxin beta receptor, Nucleoporin 62, CD40, TNFSF14, RANK, Caspase 3 and TANK....
, and - XIAPXIAPX-linked inhibitor of apoptosis protein also known as inhibitor of apoptosis protein 3 and baculoviral IAP repeat-containing protein 4 is a protein that in humans is encoded by the XIAP gene....
.
Biological function
Caspase-3 has been found to be necessary for normal brainBrain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
development as well as its typical role in apoptosis, where it is responsible for chromatin
Chromatin
Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell. The primary functions of chromatin are; to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and prevent DNA damage, and to control gene...
condensation and DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
fragmentation. Elevated levels of a fragment of Caspase-3, p17, in the bloodstream is a sign of a recent myocardial infarction
Myocardial infarction
Myocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
. It is now being shown that caspase-3 may play a role in embryonic and hematopoietic stem cell
Stem cell
This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...
differentiation.
External links
- The MEROPSMeropsMerops may refer to:* Merops , a genus of bee-eaters.* MEROPS, an on-line database for peptidases.It may also refer to several figures from Greek mythology:* King of Ethiopia, husband of Clymene, who lay with Helios and bore Phaethon...
online database for peptidases and their inhibitors: C14.003 - Apoptosis & Caspase 3 - The Proteolysis MapThe Proteolysis MapThe Proteolysis MAP is an integrated web resource focused on proteases.-Rationale:PMAP is to aid the protease researchers in reasoning about proteolytic networks and metabolic pathways.-History and funding:...
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