title: Transmembrane Topologies of Ca2+-permeable Mechanosensitive Channels MCA1 and MCA2 in Arabidopsis thaliana.
abstract: Sensing mechanical stresses, including touch, stretch, compression, and gravity, is crucial for growth and development in plants. A good mechanosensor candidate is the Ca(2+)-permeable mechanosensitive (MS) channel, the pore of which opens to permeate Ca(2+) 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 Ca(2+)-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 Ca(2+) and protein interactions.
authors.affiliation: From the Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei, Tokyo 184-8501, Japan and.
authors.forename: Shumpei
authors.initials: S
authors.lastname: Kamano
authors.affiliation: From the Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei, Tokyo 184-8501, Japan and.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Kume
authors.affiliation: Laboratory of Biomembrane, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo 156-8506, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Iida
authors.affiliation: From the Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei, Tokyo 184-8501, Japan and.
authors.forename: Kai-Jian
authors.initials: KJ
authors.lastname: Lei
authors.affiliation: From the Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei, Tokyo 184-8501, Japan and.
authors.forename: Masataka
authors.initials: M
authors.lastname: Nakano
authors.affiliation: From the Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei, Tokyo 184-8501, Japan and.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Nakayama
authors.affiliation: From the Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei, Tokyo 184-8501, Japan and iida@u-gakugei.ac.jp.
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Iida
mesh_terms: D020816:Amino Acid Motifs; D017360:Arabidopsis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; C520286:MCA1 protein, Arabidopsis; C000591896:MCA2 protein, Arabidopsis; D008565:Membrane Proteins; D002118:Calcium
keywords: Arabidopsis thaliana; calcium; calcium channel; calcium transport; mechanotransduction; membrane protein; plant molecular biology; transmembrane domain