Main Orthology Inference Function

This function takes nucleotide or protein sequences for a set of organisms and performs orthology inference to detect orthologous genes within the given organisms based on selected orthology inference programs.

orthologs(
  query_file,
  subject_files,
  seq_type = "protein",
  outgroup_file = NULL,
  eval = "1E-5",
  format = "fasta",
  ortho_detection = "RBH",
  delete_corrupt_cds = FALSE,
  cdd.path = NULL,
  path = NULL,
  add_params = NULL,
  comp_cores = 1,
  quiet = FALSE,
  clean_folders = FALSE
)

Arguments

query_file

a character string specifying the path to the sequence file of interest (query organism).

subject_files

a character string specifying the paths to the sequence files of interest (subject organisms). Different orthology inference methods can detect orthologs using multiple subject organisms, e.g. "OrthoMCL", and "PO" (ProteinOrtho).

seq_type

a character string specifying the sequence type stored in the input file. Options are are: "cds", "protein", or "dna". In case of "cds", sequence are translated to protein sequences, in case of "dna", cds prediction is performed on the corresponding sequences which subsequently are translated to protein sequences. Default is seq_type = "protein".

outgroup_file

a character string specifying the paths to the sequence files of interest (outgroup organisms). This argument is only used by InParanoid.

eval

a numeric value specifying the E-Value cutoff for BLAST hit detection.

format

a character string specifying the file format of the sequence file, e.g. "fasta", "gbk". Default is "fasta".

ortho_detection

a character string specifying the orthology inference method that shall be performed to detect orthologous genes. Default is ortho_detection = "RBH" (BLAST reciprocal best hit). Further methods are: "RBH" (BLAST reciprocal best hit), "PO" (ProteinOrtho), and "OrthoMCL.

delete_corrupt_cds

a logical value indicating whether sequences with corrupt base triplets should be removed from the input file. This is the case when the length of coding sequences cannot be divided by 3 and thus the coding sequence contains at least one corrupt base triplet.

cdd.path

path to the cdd database folder (specify when using ortho_detection = "DELTA").

path

a character string specifying the path to the corresponding orthology inference tool. For "BH" and "RBH": path to BLAST, "PO": path to ProteinOrtho 5.07, "OrthoMCL": path to OrthoMCL.

add_params

a character string specifying additional parameters that shall be handed to the orthology inference method (tool). Default is add_params = NULL.

comp_cores

a numeric value specifying the number of cores to be used for multicore computations.

quiet

a logical value specifying whether a successful interface call shall be printed out.

clean_folders

a boolean value spefiying whether all internall folders storing the output of used programs shall be removed. Default is clean_folders = FALSE.

Value

A data.table storing the query_ids of orthologous genes in the first column, the subject_ids of orthologous genes in the second column and the amino acid sequences in the third column.

Details

This function takes sequence files of a query organism and a subject organism and performs orthology inference using a defined orthology inference method to dectect orthologous genes.

The following interfaces are implemented in the orthologs function:

BLAST based methods:

• BLAST best hit (BH)

• BLAST reciprocal best hit (RBH)

• DELTA-BLAST reciprocal best hit (DELTA)

See also

blast_rec, dNdS

Author

Hajk-Georg Drost

Examples

if (FALSE) {

### BLAST Best Hit

# perform orthology inference using BLAST best hit
# and fasta sequence files storing protein sequences
orthologs(query_file      = system.file('seqs/ortho_thal_aa.fasta', package = 'orthologr'),
          subject_files   = system.file('seqs/ortho_lyra_aa.fasta', package = 'orthologr'),
          seq_type        = "protein", 
          ortho_detection = "BH")


### BLAST Reciprocal Best Hit

# perform orthology inference using BLAST reciprocal best hit
# and fasta sequence files storing protein sequences
orthologs(query_file      = system.file('seqs/ortho_thal_aa.fasta', package = 'orthologr'),
          subject_files   = system.file('seqs/ortho_lyra_aa.fasta', package = 'orthologr'),
          seq_type        = "protein", 
          ortho_detection = "RBH")
          
          
# multicore version          
orthologs(query_file      = system.file('seqs/ortho_thal_aa.fasta', package = 'orthologr'),
          subject_files   = system.file('seqs/ortho_lyra_aa.fasta', package = 'orthologr'),
          seq_type        = "protein", 
          ortho_detection = "RBH", 
          comp_cores      = 2)          
}