Messenger RNA Design via Expected Partition Function and Continuous Optimization
This addresses the challenge of mRNA design for vaccines and therapeutics, offering a novel method for optimizing ensemble free energy, though it builds on existing approaches.
The paper tackles the NP-hard problem of RNA design by formulating it as continuous optimization using an expected partition function, and demonstrates improvements in ensemble free energy over LinearDesign, especially for longer sequences.
The tasks of designing RNAs are discrete optimization problems, and several versions of these problems are NP-hard. As an alternative to commonly used local search methods, we formulate these problems as continuous optimization and develop a general framework for this optimization based on a generalization of classical partition function which we call "expected partition function". The basic idea is to start with a distribution over all possible candidate sequences, and extend the objective function from a sequence to a distribution. We then use gradient descent-based optimization methods to improve the extended objective function, and the distribution will gradually shrink towards a one-hot sequence (i.e., a single sequence). As a case study, we consider the important problem of mRNA design with wide applications in vaccines and therapeutics. While the recent work of LinearDesign can efficiently optimize mRNAs for minimum free energy (MFE), optimizing for ensemble free energy is much harder and likely intractable. Our approach can consistently improve over the LinearDesign solution in terms of ensemble free energy, with bigger improvements on longer sequences.