Functional analysis of PsbS transmembrane domains through base editing in Physcomitrium patens

Plants exposed to light fluctuations are protected from photodamage by non-photochemical quenching (NPQ), a reversible mechanism that enables dissipation of excess absorbed energy as heat, which is essential for plant fitness and crop productivity. In plants NPQ requires the presence of the membrane protein PsbS, which upon activation interacts with antenna proteins, inducing their dissipative conformation. Here, we exploited base editing (BE) in the moss Physcomitrium patens to introduce specific amino acid changes in vivo and assess their impact on PsbS activity, targeting transmembrane regions to investigate their role in essential protein-protein interactions. This approach enabled the recognition of residues essential for protein stability and the identification of a hydrophobic cluster of amino acids impacting PsbS activity. This work provides new information on the molecular mechanism of PsbS while also demonstrating the potential of BE approaches for in planta gene function analysis.

Automated summary

Plants use non-photochemical quenching (NPQ) as a reversible mechanism to dissipate excess absorbed energy as heat, protecting them from photodamage. The presence of the membrane protein PsbS is essential for NPQ in plants, as it interacts with antenna proteins to induce dissipative conformation. This study utilized base editing in the moss Physcomitrium patens to investigate the role of specific amino acid changes in PsbS and identified residues and hydrophobic amino acid clusters that impact PsbS activity, providing new insights into its molecular mechanism.