Adenosylmethionine decarboxylase
Encyclopedia
Adenosylmethionine decarboxylase is an enzyme that catalyzes the conversion of S-adenosyl methionine
to S-adenosylmethioninamine
.
Polyamine
s such as spermidine
and spermine
are essential for cellular
growth
under most conditions, being implicated in a large number of cellular processes including DNA, RNA and protein synthesis
. S-adenosylmethionine decarboxylase (AdoMetDC) plays an essential regulatory role in the polyamine biosynthetic pathway by generating the n-propylamine residue required for the synthesis of spermidine and spermine from putrescein. Unlike many amino acid
decarboxylases AdoMetDC uses a covalently bound pyruvate residue as a cofactor
rather than the more common pyridoxal 5'-phosphate. These protein
s can be divided into two main groups which show little sequence
similarity either to each other, or to other pyruvoyl-dependent amino acid decarboxylases: class I enzyme
s found in bacteria
and archaea
, and class II enzymes found in eukaryotes. In both groups the active enzyme is generated by the post-translational autocatalytic cleavage
of a precursor protein
. This cleavage generates the pyruvate precursor from an internal serine
residue and results in the formation of two non-identical subunits
termed alpha and beta which form the active enzyme.
S-Adenosyl methionine
S-Adenosyl methionine is a common cosubstrate involved in methyl group transfers. SAM was first discovered in Italy by G. L. Cantoni in 1952. It is made from adenosine triphosphate and methionine by methionine adenosyltransferase . Transmethylation, transsulfuration, and aminopropylation are the...
to S-adenosylmethioninamine
S-Adenosylmethioninamine
S-Adenosylmethioninamine is a substrate that is involved in the biosynthesis of polyamines including spermidine, spermine, and thermospermine.- See also :* ACAULIS5* Adenosylmethionine decarboxylase...
.
Polyamine
Polyamine
A polyamine is an organic compound having two or more primary amino groups .This class of compounds includes several synthetic substances that are important feedstocks for the chemical industry, such as ethylene diamine , 1,3-diaminopropane , and hexamethylenediamine...
s such as spermidine
Spermidine
Spermidine is a polyamine involved in cellular metabolism. Its known actions include:#Inhibition of neuronal nitric oxide synthase, nNOS#Assisting the in vitro process of transcribing RNA via stimulation of T4 polynucleotide kinase and T7 RNA polymerase activity; it binds to and precipitates DNA...
and spermine
Spermine
Spermine is a polyamine involved in cellular metabolism found in all eukaryotic cells. Formed from spermidine, it is found in a wide variety of organisms and tissues and is an essential growth factor in some bacteria. It is found as a polycation at physiological pH...
are essential for cellular
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
growth
Cell growth
The term cell growth is used in the contexts of cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"...
under most conditions, being implicated in a large number of cellular processes including DNA, RNA and protein synthesis
Protein biosynthesis
Protein biosynthesis is the process in which cells build or manufacture proteins. The term is sometimes used to refer only to protein translation but more often it refers to a multi-step process, beginning with amino acid synthesis and transcription of nuclear DNA into messenger RNA, which is then...
. S-adenosylmethionine decarboxylase (AdoMetDC) plays an essential regulatory role in the polyamine biosynthetic pathway by generating the n-propylamine residue required for the synthesis of spermidine and spermine from putrescein. Unlike many amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
decarboxylases AdoMetDC uses a covalently bound pyruvate residue as a cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
rather than the more common pyridoxal 5'-phosphate. These 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...
s can be divided into two main groups which show little sequence
Sequence (biology)
A sequence in biology is the one-dimensional ordering of monomers, covalently linked within in a biopolymer; it is also referred to as the primary structure of the biological macromolecule.-See also:* Protein sequence* DNA sequence...
similarity either to each other, or to other pyruvoyl-dependent amino acid decarboxylases: class I 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...
s found in bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and archaea
Archaea
The Archaea are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon...
, and class II enzymes found in eukaryotes. In both groups the active enzyme is generated by the post-translational autocatalytic cleavage
Cleavage
Cleavage may refer to:*Cleavage , partial exposure of the separation between a woman's breasts.**Cleavage enhancement, methods of making a person's breast cleavage look more substantial than it really is....
of a precursor protein
Protein precursor
A protein precursor, also called a pro-protein or pro-peptide, is an inactive protein that can be turned into an active form by posttranslational modification. The name of the precursor for a protein is often prefixed by pro...
. This cleavage generates the pyruvate precursor from an internal serine
Serine
Serine is an amino acid with the formula HO2CCHCH2OH. It is one of the proteinogenic amino acids. By virtue of the hydroxyl group, serine is classified as a polar amino acid.-Occurrence and biosynthesis:...
residue and results in the formation of two non-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...
termed alpha and beta which form the active enzyme.