Cross-species assembly of optimal isomerases DbZISO and DsCRTISO enhances all-trans-lycopene production in engineered...

Lycopene is a high-value antioxidant, yet its microbial production is often limited by inefficient cis-trans isomerization steps in heterologous carotenoid pathways. This study systematically compared two key carotenoid isomerases, ZISO and CRTISO, from Dunaliella salina (Ds) and Dunaliella bardawil (Db). Molecular docking and dynamic simulations revealed that DbZISO exhibited superior substrate binding (binding energy: -13.09 kcal/mol) and conformational stability, whereas DsCRTISO showed higher catalytic efficiency toward 7,7',9,9'-tetra-cis-lycopene than DbCRTISO. Based on these results, Dbziso and Dscrtiso were co-expressed in E. coli to generate the recombinant strain DsZC. After single-factor and response surface methodology (RSM) optimization, DsZC produced 1.56 ± 0.06 mg/g DCW all-trans-lycopene under the optimized conditions (0.48 mM IPTG, 27.7 °C, 0.3 mM δ-ALA, 48 h), representing a 1.24-fold increase over the native DsCRT pathway. This study demonstrates that cross-species combination of optimally performing isomerases is an effective strategy to boost lycopene biosynthesis, offering a viable platform for industrial carotenoid production.