A genetically encoded fluorescent sensor for manganese(II), engineered from lanmodulin

Area of Science:

• Biochemistry
• Chemical Biology
• Protein Engineering

Background:

• Designing selective metal-binding sites is challenging, especially for manganese (II) due to its low ligand affinity.
• A lack of tools hinders the study of manganese physiology in live cells, impacting fields like photosynthesis and neurobiology.

Purpose of the Study:

• To develop genetically encoded fluorescent sensors for selective manganese (II) detection.
• To re-engineer the lanthanide-binding protein, lanmodulin, for manganese sensing.

Main Methods:

• Rational re-engineering of lanmodulin to create MnLaMP1 and MnLaMP2 sensors.
• In vitro and in vivo detection of manganese (II) using the developed sensors.
• Application of sensors to visualize bacterial labile manganese pools.

Main Results:

• Developed two fluorescent sensors, MnLaMP1 and MnLaMP2, with effective dissociation constants (Kd) for Mn(II) of 29 and 7 µM, respectively.
• Demonstrated selective detection of Mn(II) in vitro and in vivo, defying the Irving-Williams series.
• Visualized the kinetics of labile manganese pools in bacteria.

Conclusions:

• Lanmodulin serves as a versatile scaffold for creating selective protein-based biosensors and chelators.
• The engineered sensors provide crucial tools for studying manganese physiology in live cellular environments.
• Understanding coordinated solvent and hydrophobic interactions is key to sensor selectivity.