Summary: DALR domain
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This is the Wikipedia entry entitled "Aminoacyl tRNA synthetase". More...
Aminoacyl tRNA synthetase
| leucyl-trna synthetase from thermus thermophilus complexed with a post-transfer editing substrate analogue | |||||||||
| Identifiers | |||||||||
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| Symbol | Anticodon_1 | ||||||||
| Pfam | PF08264 | ||||||||
| InterPro | IPR013155 | ||||||||
| SCOP | 1ivs | ||||||||
| SUPERFAMILY | 1ivs | ||||||||
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| thermus thermophilus arginyl-trna synthetase | |||||||||
| Identifiers | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | DALR_1 | ||||||||
| Pfam | PF05746 | ||||||||
| Pfam clan | CL0258 | ||||||||
| InterPro | IPR008909 | ||||||||
| SCOP | 1bs2 | ||||||||
| SUPERFAMILY | 1bs2 | ||||||||
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| crystal structure of cysteinyl-trna synthetase binary complex with trnacys | |||||||||
| Identifiers | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Symbol | DALR_2 | ||||||||
| Pfam | PF09190 | ||||||||
| Pfam clan | CL0258 | ||||||||
| InterPro | IPR015273 | ||||||||
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An aminoacyl tRNA synthetase (aaRS) is an enzyme that catalyzes the esterification of a specific amino acid or its precursor to one of all its compatible cognate tRNAs to form an aminoacyl-tRNA. This is sometimes called "charging" the tRNA with the amino acid. Once the tRNA is charged, a ribosome can transfer the amino acid from the tRNA onto a growing peptide, according to the genetic code.
Contents |
[edit] Mechanism
The synthetase first binds ATP and the corresponding amino acid or its precursor to form an aminoacyl-adenylate and release inorganic pyrophosphate (PPi). The adenylate-aaRS complex then binds the appropriate tRNA molecule, and the amino acid is transferred from the aa-AMP to either the 2'- or the 3'-OH of the last tRNA nucleotide (A76) at the 3'-end. Some synthetases also mediate a proofreading reaction to ensure high fidelity of tRNA charging; if the tRNA is found to be improperly charged, the aminoacyl-tRNA bond is hydrolyzed.
[edit] Reaction
Reaction:
- amino acid + ATP → aminoacyl-AMP + PPi
- aminoacyl-AMP + tRNA → aminoacyl-tRNA + AMP
Sum of 1 and 2: amino acid + tRNA + ATP → aminoacyl-tRNA + AMP + PPi
[edit] Classes
There are two classes of aminoacyl tRNA synthetase:[1]
- Class I has two highly conserved sequence motifs. It aminoacylates at the 2'-OH of an adenosine nucleotide, and is usually monomeric or dimeric (one or two subunits, respectively).
- Class II has three highly conserved sequence motifs. It aminoacylates at the 3'-OH of the same adenosine, and is usually dimeric or tetrameric (two or four subunits, respectively). Although phenylalanine-tRNA synthetase is class II, it aminoacylates at the 2'-OH.
The amino acids are attached to the hydroxyl (-OH) group of the adenosine via the carboxyl (-COOH) group.
Regardless of where the aminoacyl is initially attached to the nucleotide, the 2'-O-aminoacyl-tRNA will ultimately migrate to the 3' position via transesterification.
[edit] Structures
Both classes of aminoacyl-tRNA synthetases are multidomain proteins. In a typical scenario, an aaRS consists of a catalytic domain (where both the above reactions take place) and an anticodon binding domain (which interacts mostly with the anticodon region of the tRNA and ensures binding of the correct tRNA to the amino acid). In addition, some aaRSs have additional RNA binding domains and editing domains[2] that cleave incorrectly paired aminoacyl-tRNA molecules.
The catalytic domains of all the aaRSs of a given class are found to be homologous to one another, whereas class I and class II aaRSs are unrelated to one another. The class I aaRSs have the ubiquitous Rossmann fold and have the antiparallel beta-strands architecture, whereas the class II aaRSs have a unique fold made up of antiparallel beta-strands.
The alpha helical anticodon binding domain of Arginyl, Glycyl and Cysteinyl-tRNA synthetases is known as the DALR domain after characteristic conserved amino acids.[3]
[edit] Evolution
Most of the aaRSs of a given specificity are evolutionarily closer to one another than to aaRSs of another specificity. However, AsnRS and GlnRS group within AspRS and GluRS, respectively. Most of the aaRSs of a given specificity also belong to a single class. However, there are two distinct versions of the LysRS - one belonging to the class I family and the other belonging to the class II family.
In addition, the molecular phylogenies of aaRSs are often not consistent with accepted organismal phylogenies, e.g. they violate the so-called canonical phylogenetic pattern shown by most other enzymes for the three domains of life - Archaea, Bacteria, and Eukarya. Furthermore, the phylogenies inferred for aaRSs of different amino acids often do not agree with one another. These are two clear indications that horizontal transfer has occurred several times during the evolutionary history of aaRSs (Carl R. Woese, Gary J. Olsen, Michael Ibba, and Dieter Söll. Microbiology and Molecular Biology Reviews, March 2000, p. 202-236, Vol. 64, No. 1: Aminoacyl-tRNA Synthetases, the Genetic Code, and the Evolutionary Process).
[edit] Expanding the genetic code via mutant aminoacyl tRNA synthetases
In some of the aminoacyl tRNA synthetases, the cavity that holds the amino acid can be mutated and modified to carry artificial, unnatural amino acids synthesized in the lab, and to attach them to specific tRNAs. This expands the genetic code, beyond the twenty amino acids universal in nature, to include an unnatural amino acid as well. The unnatural amino acid is coded by an otherwise non-coding base triplet such as the amber stop codon. The organism that expresses the mutant synthetase can then be genetically programmed to incorporate the unnatural amino acid into any desired position in any protein of interest, allowing biochemists or structural biologists to probe or change the protein's function. For instance, one can start with the gene for a protein that binds a certain sequence of DNA, and, by directing an unnatural amino acid with a reactive side-chain into the binding site, create a new protein that cuts the DNA at the target-sequence, rather than binding it.
By mutating aminoacyl tRNA synthetases, chemists have expanded the genetic codes of various organisms to include lab-synthesized amino acids with all kinds of useful properties: photoreactive, metal-chelating, xenon-chelating, crosslinking, color-changing, spin-resonant, fluorescent, biotinylated, and redox-active amino acids. [4]
[edit] Prediction Servers
- ICAARS: B. Pawar, and GPS Raghava (2010) Prediction and classification of aminoacyl tRNA synthetases using PROSITE domains. BMC Genomics 2010, 11:507
- MARSpred: B. Pawar, and GPS Raghava (2011) Predicting sub-cellular localization of tRNA synthetases from their primary structures. Amino Acids 2011 PMID: 21400228
[edit] References
- ^ "tRNA Synthetases". http://www.biochem.ucl.ac.uk/bsm/xtal/teach/trna/trna.html. Retrieved 2007-08-18.
- ^ "High Fidelity". http://www.pdb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb16_3.html. Retrieved 2007-08-18.
- ^ Wolf YI, Aravind L, Grishin NV, Koonin EV (August 1999). "Evolution of aminoacyl-tRNA synthetases--analysis of unique domain architectures and phylogenetic trees reveals a complex history of horizontal gene transfer events". Genome Res. 9 (8): 689–710. doi:10.1101/gr.9.8.689. PMID 10447505.
- ^ Peter G. Schultz, Expanding the genetic code
[edit] See also
[edit] External links
This article incorporates text from the public domain Pfam and InterPro IPR015273
This article incorporates text from the public domain Pfam and InterPro IPR008909
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This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.
This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.
DALR domain
This DALR domain is found in cysteinyl-tRNA-synthetases [1].
Literature references
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Wolf YI, Aravind L, Grishin NV, Koonin EV; , Genome Res 1999;9:689-710.: Evolution of aminoacyl-tRNA synthetases--analysis of unique domain architectures and phylogenetic trees reveals a complex history of horizontal gene transfer events. PUBMED:10447505
Clan
This family is a member of clan DALR (CL0258), which has a total of 2 members.
External database links
| PANDIT: | PF09190 |
| Pseudofam: | PF09190 |
| SYSTERS: | DALR_2 |
This tab holds annotation information from the InterPro database.
InterPro entry IPR015273
The aminoacyl-tRNA synthetases (EC) catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction. These proteins differ widely in size and oligomeric state, and have limited sequence homology [PUBMED:2203971]. The 20 aminoacyl-tRNA synthetases are divided into two classes, I and II. Class I aminoacyl-tRNA synthetases contain a characteristic Rossman fold catalytic domain and are mostly monomeric [PUBMED:10673435]. Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices [PUBMED:8364025], and are mostly dimeric or multimeric, containing at least three conserved regions [PUBMED:8274143, PUBMED:2053131, PUBMED:1852601]. However, tRNA binding involves an alpha-helical structure that is conserved between class I and class II synthetases. In reactions catalysed by the class I aminoacyl-tRNA synthetases, the aminoacyl group is coupled to the 2'-hydroxyl of the tRNA, while, in class II reactions, the 3'-hydroxyl site is preferred. The synthetases specific for arginine, cysteine, glutamic acid, glutamine, isoleucine, leucine, methionine, tyrosine, tryptophan and valine belong to class I synthetases; these synthetases are further divided into three subclasses, a, b and c, according to sequence homology. The synthetases specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, phenylalanine, proline, serine, and threonine belong to class-II synthetases [PUBMED:].
This DALR domain is found in cysteinyl-tRNA-synthetases [PUBMED:10447505].
Gene Ontology
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
| Cellular component | cytoplasm (GO:0005737) |
| Molecular function | cysteine-tRNA ligase activity (GO:0004817) |
| ATP binding (GO:0005524) | |
| nucleotide binding (GO:0000166) | |
| Biological process | cysteinyl-tRNA aminoacylation (GO:0006423) |
| translation (GO:0006412) |
Domain organisation
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
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Pfam Clan
Alignments
There are various ways to view or download the sequence alignments that we store. You can use a sequence viewer to look at either the seed or full alignment for the family, or you can look at a plain text version of the sequence in a variety of different formats. More...
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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
The main seed and full alignments are generated using sequences from the UniProt sequence database. However, we also generate alignments using sequences from the NCBI sequence database and the "metaseq" metagenomics dataset.
You can view alignments from these two additional datasets using the form above, or you can download alignments of NCBI or metagenomics sequences, as gzip-compressed files.
External links
MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.
HMM logo
HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...
Trees
This page displays the phylogenetic tree for this family. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed or full alignments.
Note: You can also download the data files for the seed, full, NCBI or metagenomics trees.
Curation and family details
This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.
Curation
| Seed source: | pdb |
| Previous IDs: | none |
| Type: | Domain |
| Author: | Sammut SJ, Bateman A |
| Number in seed: | 124 |
| Number in full: | 2802 |
| Average length of the domain: | 63.80 aa |
| Average identity of full alignment: | 30 % |
| Average coverage of the sequence by the domain: | 13.57 % |
HMM information
| HMM build commands: |
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 15929002 -E 1000 --cpu 4 HMM pfamseq
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| Model details: |
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| Model length: | 63 | ||||||||||||
| Family (HMM) version: | 6 | ||||||||||||
| Download: | download the raw HMM for this family |
Species distribution
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Colour assignments
Archea
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Eukaryota
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Bacteria
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Other sequences
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Viruses
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Unclassified
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Viroids
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Unclassified sequence
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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab if you need to select sub-trees and view sequence alignments. More...
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Interactions
There is 1 interaction for this family. More...
tRNA-synt_1eStructures
For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the DALR_2 domain has been found. There are 5 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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Archea
Eukaryota
Bacteria
Other sequences
Viruses
Unclassified
Viroids
Unclassified sequence