- AUTHOR - Heikki Lehvaslaiho
Bio::Tools::CodonTable - Bioperl codon table object
This is a read-only class for all known codon tables. The IDs are the ones used by nucleotide sequence databases. All common IUPAC ambiguity codes for DNA, RNA and animo acids are recognized. # to use use Bio::Tools::CodonTable; # defaults to ID 1 "Standard" $myCodonTable = Bio::Tools::CodonTable->new(); $myCodonTable2 = Bio::Tools::CodonTable -> new ( -id => 3 ); # change codon table $myCodonTable->id(5); # examine codon table print join (' ', "The name of the codon table no.", $myCodonTable->id(4), "is:", $myCodonTable->name(), "\n"); # translate a codon $aa = $myCodonTable->translate('ACU'); $aa = $myCodonTable->translate('act'); $aa = $myCodonTable->translate('ytr'); # reverse translate an amino acid @codons = $myCodonTable->revtranslate('A'); @codons = $myCodonTable->revtranslate('Ser'); @codons = $myCodonTable->revtranslate('Glx'); @codons = $myCodonTable->revtranslate('cYS', 'rna'); #boolean tests print "Is a start\n" if $myCodonTable->is_start_codon('ATG'); print "Is a termianator\n" if $myCodonTable->is_ter_codon('tar'); print "Is a unknown\n" if $myCodonTable->is_unknown_codon('JTG');
Codon tables are also called translation tables or genetics codes since that is what they try to represent. A bit more complete picture of the full complexity of codon usage in various taxonomic groups presented at the NCBI Genetic Codes Home page.
CodonTable is a BioPerl class that knows all current translation tables that are used by primary nucleotide sequence databases (GenBank, EMBL and DDBJ). It provides methods to output information about tables and relationships between codons and amino acids.
This class and its methods recognized all common IUPAC ambiguity codes for DNA, RNA and animo acids. The translation method follows the conventions in EMBL and TREMBL databases.
It is a nuisance to separate RNA and cDNA representations of nucleic acid transcripts. The CodonTable object accepts codons of both type as input and allows the user to set the mode for output when reverse translating. Its default for output is DNA.
Note: This class deals primarily with individual codons and amino acids. However in the interest of speed you can translate longer sequence, too. The full complexity of protein translation is tackled by Bio::PrimarySeqI::translate.
The amino acid codes are IUPAC recommendations for common amino acids:
A Ala Alanine R Arg Arginine N Asn Asparagine D Asp Aspartic acid C Cys Cysteine Q Gln Glutamine E Glu Glutamic acid G Gly Glycine H His Histidine I Ile Isoleucine L Leu Leucine K Lys Lysine M Met Methionine F Phe Phenylalanine P Pro Proline S Ser Serine T Thr Threonine W Trp Tryptophan Y Tyr Tyrosine V Val Valine B Asx Aspartic acid or Asparagine Z Glx Glutamine or Glutamic acid X Xaa Any or unknown amino acid
It is worth noting that, "Bacterial" codon table no. 11 produces an polypeptide that is, confusingly, identical to the standard one. The only differences are in available initiator codons.
NCBI Genetic Codes home page: http://www.ncbi.nlm.nih.gov/htbin-post/Taxonomy/wprintgc?mode=c
EBI Translation Table Viewer: http://www.ebi.ac.uk/cgi-bin/mutations/trtables.cgi
Amended ASN.1 version with ids 16 and 21 is at: ftp://ftp.ebi.ac.uk/pub/databases/geneticcode/
Thank your for Matteo diTomasso for the original Perl implementation of these tables.
User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to the Bioperl mailing lists Your participation is much appreciated.
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The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _
Title : id Usage : $obj->id(3); $id_integer = $obj->id(); Function: Sets or returns the id of the translation table. IDs are integers from 1 to 15, excluding 7 and 8 which have been removed as redundant. If an invalid ID is given the method returns 0, false. Example : Returns : value of id, a scalar, 0 if not a valid Args : newvalue (optional)
Title : name Usage : $obj->name() Function: returns the descriptive name of the translation table Example : Returns : A string Args : None
Title : translate Usage : $obj->translate('YTR') Function: Returns a string of one letter amino acid codes from nucleotide sequence input. The imput can be of any length. Returns 'X' for unknown codons and codons that code for more than one amino acid. Returns an empty string if input is not three characters long. Exceptions for these are: - IUPAC amino acid code B for Aspartic Acid and Asparagine, is used. - IUPAC amino acid code Z for Glutamic Acid, Glutamine is used. - if the codon is two nucleotides long and if by adding an a third character 'N', it codes for a single amino acid (with exceptions above), return that, otherwise return empty string. Returns empty string for other input strings that are not three characters long. Example : Returns : a string of one letter ambiguous IUPAC amino acid codes Args : ambiguous IUPAC nucleotide string
Title : translate_strict Usage : $obj->translate_strict('ACT') Function: returns one letter amino acid code for a codon input Fast and simple translation. User is responsible to resolve ambiguous nucleotide codes before calling this method. Returns 'X' for unknown codons and an empty string for input strings that are not three characters long. It is not recommended to use this method in a production environment. Use method translate, instead. Example : Returns : A string Args : a codon = a three nucleotide character string
Title : revtranslate Usage : $obj->revtranslate('G') Function: returns codons for an amino acid Returns an empty string for unknown amino acid codes. Ambiquous IUPAC codes Asx,B, (Asp,D; Asn,N) and Glx,Z (Glu,E; Gln,Q) are resolved. Both single and three letter amino acid codes are accepted. '*' and 'Ter' are used for terminator. By default, the output codons are shown in DNA. If the output is needed in RNA (tr/t/u/), add a second argument 'RNA'. Example : $obj->revtranslate('Gly', 'RNA') Returns : An array of three lower case letter strings i.e. codons Args : amino acid, 'RNA'
Title : is_start_codon Usage : $obj->is_start_codon('ATG') Function: returns true (1) for all codons that can be used as a translation start, false (0) for others. Example : $myCodonTable->is_start_codon('ATG') Returns : boolean Args : codon
Title : is_ter_codon Usage : $obj->is_ter_codon('GAA') Function: returns true (1) for all codons that can be used as a translation tarminator, false (0) for others. Example : $myCodonTable->is_ter_codon('ATG') Returns : boolean Args : codon
Title : is_unknown_codon Usage : $obj->is_unknown_codon('GAJ') Function: returns false (0) for all codons that are valid, true (1) for others. Example : $myCodonTable->is_unknown_codon('NTG') Returns : boolean Args : codon
Title : _unambiquous_codons Usage : @codons = _unambiquous_codons('ACN') Function: Example : Returns : array of strings (one letter unambiguous amino acid codes) Args : a codon = a three IUPAC nucleotide character string