Abstract
Recognition of phytosulfokine (PSK), a sulfated pentapeptide, by its receptor PSKRs is crucial in regulating plant growth, development, and reproduction. However, designing highly active PSK remains a formidable challenge due to the lack of understanding of the structure-property relationship, structural dynamics, and the binding characteristics of PSK. Here, with a combined theoretical and experimental approach, we have investigated the binding dynamics of key interactions between PSK and AtPSKR1LRR to reveal the molecular mechanism of PSK recognition. Our molecular dynamics simulations and free energy perturbation calculations demonstrate that the sulfated tyrosines (PSKsY1 and PSKsY3) are indispensable for forming stable PSK-AtPSKR1LRR complex, while the alanine substitution at PSKQ5 site is rather tolerated. Furthermore, two promising PSK peptide analogs (PSKQ5A and PSKQ5K) with enhanced biological activity have been designed through in silico mutagenesis studies and in vivo experiments. They have a strong promoting effect (20 % enhancement) on stimulating root development compared with the wild-type PSK treatment. This work offers an effective strategy to design new peptide-based drugs for facilitating plant growth and consequent crop productivity, potentially benefiting efforts to address the global food crisis.