OLGenie

OLGenie estimates the ratio of nonsynonymous to synonymous substitutions per site (dN/dS) in overlapping genes (OLGs) to detect purifying selection and assess functional constraints in regions with shared nucleotide sites across different reading frames.

Key Features:

• dN/dS estimation: Estimates dN/dS specifically for overlapping genes, accounting for nucleotide sites that are synonymous in one reading frame but nonsynonymous in another.
• Modified Wei–Zhang method: Implements a modified version of the Wei–Zhang method tailored to the challenges of OLGs.
• Implementation: Distributed as a Perl program.
• Selection detection: Detects purifying (negative) natural selection indicative of functional constraint in overlapping coding regions.
• Validation: Evaluated using simulations and control datasets from viral genomes, including analyses of 58 OLGs and 176 non-OLGs, demonstrating low false positive rates and discriminatory ability.
• Case study: Applied to the putative HIV-1 antisense protein gene and revealed significant purifying selection.

Scientific Applications:

• Functional constraint assessment: Assess functional constraints and selection pressures in overlapping coding regions.
• OLG identification: Support distinction between true overlapping genes and non-overlapping regions based on selection metrics.
• Genome annotation: Inform annotation of overlapping genes during genome analysis workflows.
• Viral genomics: Analyze overlapping genes in viral genomes, including targeted investigations such as HIV-1 antisense protein studies.

Methodology:

Perl implementation that estimates dN/dS for overlapping genes using a modified Wei–Zhang method and was validated with simulations and viral-genome control datasets (58 OLGs and 176 non-OLGs).