Improving activity of GenB3 and GenB4 in gentamicin dideoxygenation biosynthesis by semi-rational engineering
摘要
Aminoglycoside antibiotics continue to play an indispensable role in clinical antibacterial agents. However, the protection and deprotection procedures in the chemical pathways of semi-synthetic antibiotics are long, atom- and step-inefficient, which severely hampers the development of novel AGs.
ResultsHere, GenB3 and GenB4 are employed to synthesize sisomicin, Oxo-verdamicin, Oxo-gentamicin C1a, and Oxo-gentamicin C2a. Subsequently, a semi-rational strategy is applied to enhance the activities of GenB3 and GenB4. The activity of GenB3M1 (Q270N) towards JI-20A-P is 1.74 times higher than that of GenB3WT. Similarly, the activity of GenB3M2 (L361C/A412T/Q270N) towards JI-20Ba-P is 1.34 times higher than that of GenB3WT. The activity of GenB4M1 (L356C) towards sisomicin is 1.51 times higher than that of GenB4WT, while GenB4M2 (L356C/A407T/Q265N) towards verdamicin C2a is 1.34 times higher than that of GenB4WT. Furthermore, the beneficial effects of these mutants have been validated in engineered strains. Molecular dynamics simulations indicate that GenB3M1 establishes a hydrogen bond network in the active center, while GenB4M1 reduces the distance between K238 and the reaction center. It is also noted that the GenB3M2 exhibits a synergistic effect specifically on JI-20Ba-P, as the C6’-CH3 group stabilization restricts the movement of the substrate, which contrasts with JI-20A-P.
ConclusionOur results not only lay the foundation for the mild and efficient synthesis of C6’-modified AGs analogues but also serve as a reference for synthesizing additional single components in M. echinospora by further enhancing the dideoxygenation process.