msa

Dependencies & Environment

Package-intrinsic requirements from the Bioconductor landing page — reproduce in any R environment.

• Version: 1.44.0 · Bioconductor: 3.23 · R: ≥ 4.6
• Depends: Biostrings
• Imports: Rcpp, BiocGenerics, IRanges, S4Vectors
• System requirements: GNU make
• Install: BiocManager::install("msa")

When to Use

• Performing multiple sequence alignment of amino acid or nucleotide sequences using msa().
• Generating highly customizable, publication-ready PDF visualizations of alignments using msaPrettyPrint().
• Calculating consensus sequences and conservation scores using msaConsensusSequence() and msaConservationScore().

When NOT to Use

• For aligning massive genomic datasets (e.g., whole genomes), use minimap2 because msa is designed for gene- or protein-scale alignments.
• For basic pairwise sequence alignments, use pwalign because it is specifically built for pairwise comparisons.

Data Requirements

• Input Format: Unaligned DNA, RNA, or Amino Acid sequences.
• Structure: Loaded as an AAStringSet (or similar XStringSet) using readAAStringSet().

Key Parameters

• output ("pdf"): Format for pretty-printing (e.g., "pdf", "asis").
• showNames ("none"): Controls the display of sequence names in the printed alignment.
• showLogo ("none"): Controls the display of the sequence logo (e.g., "top", "none").
• shadingMode ("similar"): Mode for color shading in the alignment (e.g., "similar", "functional").
• type ("upperlower"): Type of consensus sequence to generate.
• askForOverwrite (FALSE): Whether to prompt before overwriting existing files during PDF generation.
• gapVsGap (0): Score assigned to gap-versus-gap matches when calculating conservation scores.

Best Practices

• Use unmasked() to retrieve the original alignment if a colmask() has been applied to hide specific columns.
• Convert alignments to other formats using msaConvert() for downstream phylogenetic analysis (e.g., with seqinr or ape).
• Use output="asis" in msaPrettyPrint() when integrating alignments into Sweave or knitr documents.

Common Pitfalls

• PDF Compilation Failures: msaPrettyPrint() failing to compile PDFs; fix this by ensuring a working LaTeX system with the texshade.sty package is installed on your system path.
• Alignments Running Off Page: Large alignments running off the page in PDFs; fix this by splitting the alignment into chunks using subseq() and printing them separately.
• Memory Exhaustion: Running ClustalW on thousands of sequences can consume excessive memory; fix this by switching to ClustalOmega for large datasets.

Alternatives

• DECIPHER: A powerful Bioconductor package for sequence alignment, database management, and oligonucleotide design.
• ape: For phylogenetic analysis and basic sequence manipulation.
• seqinr: For biological sequence retrieval and analysis.

Citations

• Bodenhofer U, Bonatesta E, Horejs-Kainrath C, Hochreiter S. (2015) "msa: an R package for multiple sequence alignment." Bioinformatics.

References

• Homepage: https://bioconductor.org/packages/msa
• Vignette: https://bioconductor.org/packages/release/bioc/vignettes/msa/inst/doc/msa.pdf

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