gCoSRNA: Generalizable Coaxial Stacking Prediction for RNA Junctions Using Secondary Structure.

Coaxial stacking between adjacent stems is a key tertiary interaction that defines the spatial organization of RNA junctions, which are core structural motifs in folded RNAs. The accurate prediction of coaxial stacking is critical for RNA 3D structure modeling, yet existing computational tools remain limited, especially for junctions with variable numbers of branches or complex topologies. Here, we present gCoSRNA, a generalizable computational framework for predicting coaxial stacking configurations using RNA sequence and secondary structure as input. Instead of developing separate models for each junction type, gCoSRNA decomposes multi-way junctions into all possible adjacent stem pairs, termed pseudo two-way junctions, and uses a unified RF classifier to evaluate stacking probabilities. Global stacking configurations are inferred by integrating these pairwise predictions, eliminating the need for explicit junction type classification. Benchmarking on two independent test sets (297 RNA junctions), including CASP15/16 and RNA-Puzzles targets, shows that gCoSRNA achieves consistently high accuracy (mean ~0.89) across junctions with two to seven branches, outperforming existing junction-specific methods. These results highlight the model's ability to capture higher-order structural features and its potential utility in RNA tertiary structure prediction pipelines.