Journal of Biological Chemistry
Volume 290, Issue 52, 25 December 2015, Pages 30901-30909
Journal home page for Journal of Biological Chemistry

Membrane Biologye
Transmembrane Topologies of Ca2+-permeable Mechanosensitive Channels MCA1 and MCA2 in Arabidopsis thaliana*Transmembrane Topologies of MS Channels, MCA1 and MCA2

https://doi.org/10.1074/jbc.M115.692574Get rights and content
Under a Creative Commons license
open access

Sensing mechanical stresses, including touch, stretch, compression, and gravity, is crucial for growth and development in plants. A good mechanosensor candidate is the Ca2+-permeable mechanosensitive (MS) channel, the pore of which opens to permeate Ca2+ in response to mechanical stresses. However, the structure-function relationships of plant MS channels are poorly understood. Arabidopsis MCA1 and MCA2 form a homotetramer and exhibit Ca2+-permeable MS channel activity; however, their structures have only been partially elucidated. The transmembrane topologies of these ion channels need to be determined in more detail to elucidate the underlying regulatory mechanisms. We herein determined the topologies of MCA1 and MCA2 using two independent methods, the Suc2C reporter and split-ubiquitin yeast two-hybrid methods, and found that both proteins are single-pass type I integral membrane proteins with extracellular N termini and intracellular C termini. These results imply that an EF hand-like motif, coiled-coil motif, and plac8 motif are all present in the cytoplasm. Thus, the activities of both channels can be regulated by intracellular Ca2+ and protein interactions.

Arabidopsis thaliana
calcium
calcium channel
calcium transport
mechanotransduction
membrane protein
plant molecular biology
transmembrane domain

Cited by (0)

*

This work was supported by Grant-in-aid for Scientific Research on Priority Area 25120708 (to H. I.) from the Ministry of Education, Culture, Sports, Science, and Technology of Japan and Grant-in-Aid for Scientific Research B 26291026 (to H. I.) from the Japan Society for the Promotion of Science. The authors declare that they have no conflicts of interest with the contents of this article.

1

These authors contributed equally to this work.

2

Present address: Dept. of Molecular Cardiovascular Biology and Pharmacology, Ehime University School of Medicine, Shitsukawa, Toon, Ehime, 791-0295, Japan.

3

Present address: Division of Biophysics and Neurobiology, Dept. of Molecular Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki 444-8585, Japan.

4

Present address: Institute of Pharmacy, Henan University, Kaifeng 475004, China.

5

Present address: Dept. of Applied Biological Science, Tokyo University of Science, Noda, Chiba 278-8510, Japan.

6

A Japan Society for the Promotion of Science Fellow (Grant 10J02008). Present address: Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia.