A functional chimeric membrane subunit of an ion-translocating ATPase

Area of Science:

• Molecular Biology
• Biochemistry
• Microbiology

Background:

• The Ars system mediates arsenite resistance and transport in bacteria.
• Understanding the mechanisms of arsenic transport is crucial for combating antibiotic resistance and developing detoxification strategies.

Purpose of the Study:

• To construct and characterize a chimeric ArsB transport protein by fusing genes from Escherichia coli and Staphylococcus aureus.
• To investigate the energy dependence of arsenite efflux mediated by the chimeric ArsB protein and its interaction with ArsA.

Main Methods:

• Gene fusion of arsB from E. coli plasmid R773 and S. aureus plasmid pI258 to create a chimeric gene.
• Expression of the chimeric arsB gene and analysis of arsenite resistance and transport.
• Co-expression of arsA in trans with various arsB genes (R773, pI258, and chimeric) to study arsenite efflux.

Main Results:

• A functional chimeric ArsB protein was successfully synthesized, comprising the N-terminal helices from S. aureus and C-terminal helices from E. coli.
• The hybrid protein conferred arsenite resistance and facilitated arsenite transport.
• Arsenite efflux was found to be dependent on chemical energy when arsA was co-expressed, but not electrochemical energy.

Conclusions:

• The chimeric ArsB protein is functional and capable of arsenite transport.
• The Ars system's transport mechanism may involve both primary ATP-driven pumping and secondary carrier functions, influenced by subunit composition.
• This study provides insights into the modular nature and functional adaptability of bacterial arsenic transport systems.