Membrane-bound pyrophosphatase of human gut microbe Clostridium methylpentosum confers improved salt tolerance in Escherichia coli, Saccharomyces cerevisiae and tobacco

Abstract

Membrane-bound pyrophosphatases (PPases) are involved in the adaption of organisms to stress conditions, which was substantiated by numerous plant transgenic studies with H⁺-PPase yet devoid of any correlated evidences for other two subfamilies, Na⁺-PPase and Na⁺,H⁺-PPase. Herein, we demonstrate the gene cloning and functional evaluation of the membrane-bound PPase (CmPP) of the human gut microbe Clostridium methylpentosum. The CmPP gene encodes a single polypeptide of 699 amino acids that was predicted as a multi-spanning membrane and K⁺-dependent Na⁺,H⁺-PPase. Heterologous expression of CmPP could significantly enhance the salt tolerance of both Escherichia coli and Saccharomyces cerevisiae, and this effect in yeast could be fortified by N-terminal addition of a vacuole-targeting signal peptide from the H⁺-PPase of Trypanosoma cruzi. Furthermore, introduction of CmPP could remarkably improve the salt tolerance of tobacco, implying its potential use in constructing salt-resistant transgenic crops. Consequently, the possible mechanisms of CmPP to underlie salt tolerance are discussed.

Keywords:

• Membrane-bound Na⁺
• H⁺-PPase
• Clostridium methylpentosum
• heterologous expression
• salt tolerance

Acknowledgements

We thank Prof. Roberto A. Gaxiola (Arizona State University, USA) for a gift of the salt-sensitive S. cerevisiae mutant strain ena1^- (L5709). We also thank reviewers for their instructional comments for revision.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by the grants from the National Foundations of Natural Sciences, China (No. 31460067, 31160169).