Engineering nanowires in bacteria to elucidate electron transport structural-functional relationships

Area of Science:

• Microbiology
• Biophysics
• Bioelectrochemistry

Background:

• Bacterial nanowires, particularly type-IV pilin-based structures, are implicated in electron transfer and cell communication.
• The precise nature and function of these protein nanowires remain debated, with limited structure-function analyses in whole bacteria.
• Understanding these conductive pili is crucial for bio-electrical applications and microbial energy metabolism.

Purpose of the Study:

• To investigate the structure-function relationship of type-IV pilus proteins in bacterial nanowires.
• To establish how aromatic modifications influence the conductivity and structure of these protein nanowires.
• To characterize functional type-IV pili protein nanowires produced under aerobic conditions.

Main Methods:

• Engineered Cupriavidus necator H16 to express modified type-IV pilus proteins.
• Utilized high-resolution PeakForce tunnelling atomic force microscopy (PeakForce TUNA™) for nanoscale imaging.
• Employed conventional electrochemical methods to analyze conductivity of bacterial nanowires.

Main Results:

• Demonstrated the successful engineering of Cupriavidus necator H16 for producing functional type-IV pili protein nanowires.
• Established a link between specific aromatic modifications of pili proteins and their resulting conductivity.
• Provided high-resolution structural data of conductive nanowires emanating from whole bacterial cells.
• Achieved the first reported production of functional type-IV pili protein nanowires under aerobic conditions in this bacterial chassis.

Conclusions:

• This work provides the first functional characterization of type-IV pili protein nanowires produced aerobically.
• The study elucidates structure-function relationships, crucial for understanding bacterial electron transfer and communication.
• Findings have significant implications for bio-electrical applications and microbial bioenergetics.