Protein splicing
Encyclopedia
Protein splicing is an intramolecular reaction of a particular protein
in which an internal protein segment (called an intein
) is removed from a precursor protein with a ligation of C-terminal and N-terminal external proteins (called exteins) on both sides. The splicing junction of the precursor protein is mainly a cysteine
or a serine
, which are amino acid
s containing a nucleophilic side chain
. The protein splicing reactions which are known now do not require exogenous cofactors or energy sources such as adenosine triphosphate
(ATP) or guanosine triphosphate
(GTP). Normally, splicing is associated only with pre-mRNA splicing
.
intein. The maxi-inteins are N- and C-terminal splicing domains containing an endonuclease domain. The mini-inteins are typical N- and C-terminal splicing domains; however, the endonuclease domain is not present. The trans-splicing inteins are split inteins which are divided into N-termini and C-termini. Alanine inteins have the splicing junction of an alanine instead of a cysteine or a serine, in both of which the protein splicing occurs.
VMA1 in a precursor of a vacuolar H+-ATPase
. The amino acid sequence of the N- and C-termini corresponded to 70% of that of a vacuolar H+-ATPase from other organisms, while the amino acid sequence of the central position corresponded to 30% of that of the yeast
HO nuclease
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...
in which an internal protein segment (called an intein
Intein
An intein is a segment of a protein that is able to excise itself and rejoin the remaining portions with a peptide bond. Inteins have also been called "protein introns"....
) is removed from a precursor protein with a ligation of C-terminal and N-terminal external proteins (called exteins) on both sides. The splicing junction of the precursor protein is mainly 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...
or a 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:...
, which are 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...
s containing a nucleophilic side chain
Side chain
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called "main chain" or backbone. The placeholder R is often used as a generic placeholder for alkyl group side chains in chemical structure diagrams. To indicate other non-carbon...
. The protein splicing reactions which are known now do not require exogenous cofactors or energy sources such as adenosine triphosphate
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...
(ATP) or guanosine triphosphate
Guanosine triphosphate
Guanosine-5'-triphosphate is a purine nucleoside triphosphate. It can act as a substrate for the synthesis of RNA during the transcription process...
(GTP). Normally, splicing is associated only with pre-mRNA splicing
Splicing (genetics)
In molecular biology and genetics, splicing is a modification of an RNA after transcription, in which introns are removed and exons are joined. This is needed for the typical eukaryotic messenger RNA before it can be used to produce a correct protein through translation...
.
Types of inteins
The type of the splicing proteins is categorized into four classes: maxi-intein, mini-intein, trans-splicing intein, and alanineAlanine
Alanine is an α-amino acid with the chemical formula CH3CHCOOH. The L-isomer is one of the 20 amino acids encoded by the genetic code. Its codons are GCU, GCC, GCA, and GCG. It is classified as a nonpolar amino acid...
intein. The maxi-inteins are N- and C-terminal splicing domains containing an endonuclease domain. The mini-inteins are typical N- and C-terminal splicing domains; however, the endonuclease domain is not present. The trans-splicing inteins are split inteins which are divided into N-termini and C-termini. Alanine inteins have the splicing junction of an alanine instead of a cysteine or a serine, in both of which the protein splicing occurs.
History
Protein splicing was reported by two groups (Anraku and Stevens) in 1990. They both discovered a Saccharomyces cerevisiaeSaccharomyces cerevisiae
Saccharomyces cerevisiae is a species of yeast. It is perhaps the most useful yeast, having been instrumental to baking and brewing since ancient times. It is believed that it was originally isolated from the skin of grapes...
VMA1 in a precursor of a vacuolar H+-ATPase
ATPase
ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate into adenosine diphosphate and a free phosphate ion. This dephosphorylation reaction releases energy, which the enzyme harnesses to drive other chemical reactions that would not otherwise occur...
. The amino acid sequence of the N- and C-termini corresponded to 70% of that of a vacuolar H+-ATPase from other organisms, while the amino acid sequence of the central position corresponded to 30% of that of the yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
HO nuclease
Nuclease
A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. Older publications may use terms such as "polynucleotidase" or "nucleodepolymerase"....