Lithium-sensing riboswitch classes regulate expression of bacterial cation transporter genes

Area of Science:

• Biochemistry
• Microbiology
• Environmental Science

Background:

• Lithium (Li+) is less abundant than sodium (Na+) and potassium (K+) but can reach toxic levels.
• Bacteria possess ion transporters that often have low selectivity between Na+ and Li+.

Purpose of the Study:

• To experimentally validate bacterial riboswitches that respond to elevated Li+ concentrations.
• To understand the role of these riboswitches and associated transporters in preventing Li+ toxicity.

Main Methods:

• Experimental validation of riboswitch activity.
• Analysis of gene expression regulation by Li+-responsive riboswitches.
• Investigation of nhaA gene products (ion transporters).

Main Results:

• Two distinct bacterial riboswitch classes that activate gene expression in response to Li+ were identified.
• These riboswitches regulate nhaA genes, coding for transporters with weak Li+/Na+ discrimination.
• The findings indicate a primary role in preventing Li+ toxicity, particularly at high pH.

Conclusions:

• Bacterial Li+-riboswitches and NhaA transporters are crucial for defense against lithium toxicity.
• These systems are vital for bacterial survival in environments with high Li+ concentrations.
• Understanding these mechanisms is important given increasing industrial applications of lithium.