FASTX-Toolkit

FASTX-Toolkit performs preprocessing and translation-based sequence comparisons of short-reads in FASTA/FASTQ formats to detect protein-coding regions and frameshifts by aligning translated DNA sequences to protein databases.

Key Features:

• Sequence comparison programs: The suite includes FASTX, FASTY, TFASTX, and TFASTY for comparative analysis between DNA and protein sequences.
• Translation and alignment capabilities: FASTX and FASTY translate a DNA sequence into three reading frames and align the translations against a protein database with allowance for gaps and frameshifts, while TFASTX and TFASTY translate sequences in a DNA database across six frames and align them to a protein sequence with gaps and frameshifts.
• Frameshift and substitution handling: FASTX and TFASTX permit frameshifts only between codons, whereas FASTY and TFASTY permit substitutions and frameshifts within codons.
• Performance evaluation: The toolkit has been evaluated across penalties for gap openings, gap extensions, frameshifts, and nucleotide substitutions and performs equivalently when query sequences contain up to 10% errors.
• Statistical accuracy: FASTX and FASTY provide statistical estimates that are generally accurate but can be less reliable when out-of-frame translation yields a low-complexity protein sequence.

Scientific Applications:

• Protein-coding gene identification: The toolkit is used to detect and characterize protein-coding regions and to identify putative coding sequences in genomic data.
• Genome-wide scanning and boundary correction: It has been applied to Mycoplasma genitalium, Haemophilus influenzae, and Methanococcus jannaschii, identifying at least nine new protein-coding genes and discovering at least 35 genes with potentially incorrect boundaries.

Methodology:

Translate DNA sequences into multiple reading frames (three for FASTX/FASTY and six for TFASTX/TFASTY) and align translated sequences against a protein database, allowing gaps and frameshifts and evaluating penalties for gap openings, extensions, frameshifts, and nucleotide substitutions.