QueTAL

QueTAL compares and classifies Transcription Activator-Like (TAL) effectors from Xanthomonas and other taxa to infer their DNA‑binding specificities and evolutionary relationships.

Key Features:

• Repeat-based coding: Treats each nearly identical TAL repeat as a unit and transforms TAL effector sequences into coded sequences of repeats.
• DisTAL: Performs pairwise alignments between coded repeat sequences and constructs phylogenetic trees representing evolutionary relationships among TAL effectors.
• FuncTAL: Predicts potential target DNA sequences from Repeat Variable Di‑residues (RVDs), generates position weight matrices, and compares these to identify functional similarity.
• PWM correlation analysis: Calculates correlations between position weight matrices of predicted targets to quantify DNA‑binding similarity among TAL effectors.
• Phylogenetic and functional tree construction: Builds trees based on repeat-sequence alignments and on PWM-derived functional similarity to capture evolutionary and binding relationships.
• Cross-taxa comparison: Identifies TAL effectors with analogous binding properties across phylogenetically distant taxa.
• Validation: Validated using simulated datasets and literature‑curated data to assess representation of phylogenetic and functional relationships.

Scientific Applications:

• Phylogenetic analysis of TAL effectors: Infers evolutionary relationships among TAL effector genes and compares tree topology to species phylogeny.
• Prediction of DNA‑binding specificity: Identifies and compares target DNA sequences and binding specificities inferred from RVD arrays.
• Functional clustering: Groups TAL effectors by predicted promoter‑binding capabilities to detect convergent or shared targeting.
• Comparative genomics across taxa: Detects functionally similar TAL effectors in phylogenetically distant Xanthomonas strains and other taxa.
• Pathogen–host interaction studies: Supports analysis of TAL effector roles in binding plant promoter regions and inducing gene expression.

Methodology:

Transforms TAL sequences into coded repeat sequences, performs pairwise alignments of coded repeats to construct phylogenetic trees (DisTAL), predicts potential target DNA from RVD sequences, generates position weight matrices and computes correlations between PWMs to build functional‑similarity trees (FuncTAL), and validates results using simulated and literature‑curated data.