Journal of Membrane Biology

, Volume 234, Issue 1, pp 13–27

Cloning and Functional Expression of an MscL Ortholog from Rhizobium etli: Characterization of a Mechanosensitive Channel

  • Daniel Balleza
  • Froylan Gómez-Lagunas
  • Carmen Quinto
Article

DOI: 10.1007/s00232-010-9235-8

Cite this article as:
Balleza, D., Gómez-Lagunas, F. & Quinto, C. J Membrane Biol (2010) 234: 13. doi:10.1007/s00232-010-9235-8

Abstract

Rhizobium etli is equipped with several systems to handle both hyper- and hypo-osmotic stress. For adaptation to hypo-osmotic stress, R. etli possesses a single gene with clear homology to MscS, four MscS-like channels and one ortholog of MscL (ReMscL, identity ≈ 44% compared to Escherichia coli MscL). We subcloned and expressed the ReMscL channel ortholog from R. etli in E. coli to examine its activity by patch clamp in giant spheroplasts and characterized it at the single-channel level. We obtained evidence that ReMscL prevents the lysis of E. coli null mutant log-phase cells upon a rapid, osmotic downshock and identified a slight pH dependence for ReMscL activation. Here, we describe the facilitation of ReMscL activation by arachidonic acid (AA) and a reversible inhibitory effect of Gd3+. The results obtained in these experiments suggest a stabilizing effect of micromolar AA and traces of Gd3+ ions in the partially expanded conformation of the protein. Finally, we discuss a possible correlation between the number of gene paralogs for MS channels and the habitats of several microorganisms. Taken together, our data show that ReMscL may play an important role in free-living rhizobacteria during hypo-osmotic shock in the rhizosphere.

Keywords

Mechanosensitive channelRhizobium etliGating modulation

Supplementary material

232_2010_9235_MOESM1_ESM.doc (24 kb)
Supplementary material 1 (DOC 41 kb)
232_2010_9235_MOESM2_ESM.pdf (150 kb)
Supplementary material 2 (PDF 150 kb)

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Daniel Balleza
    • 1
    • 2
    • 4
  • Froylan Gómez-Lagunas
    • 2
  • Carmen Quinto
    • 3
  1. 1.Laboratory of Molecular BiologyUniversity of WisconsinMadisonUSA
  2. 2.Facultad de Medicina, Departmento de FisiologíaUNAM, México Cd. UniversitariaMexicoMexico
  3. 3.Departamento de Biología Molecular de Plantas, Instituto de BiotecnologíaUNAMCuernavacaMexico
  4. 4.Unidad de Biofísica, CSIC-UPV/EHUUniversidad del País VascoLeioaSpain