AtKC1, a silent Arabidopsis potassium channel alpha -subunit modulates root hair K+ influx.
Ion channels in roots allow the plant to gain access to nutrients. The composition of the individual ion channels and the functional contribution of different alpha-subunits is largely unknown. Focusing on K(+)-selective ion channels, we have characterized AtKC1, a new alpha-subunit from the Arabidopsis shaker-like ion channel family. Promoter-beta-glucuronidase (GUS) studies identified AtKC1 expression predominantly in root hairs and root endodermis. Specific antibodies recognized AtKC1 at the plasma membrane. To analyze further the abundance and the functional contribution of the different K(+) channels alpha-subunits in root cells, we performed real-time reverse transcription-PCR and patch-clamp experiments on isolated root hair protoplasts. Studying all shaker-like ion channel alpha-subunits, we only found the K(+) inward rectifier AtKC1 and AKT1 and the K(+) outward rectifier GORK to be expressed in this cell type. Akt1 knockout plants essentially lacked inward rectifying K(+) currents. In contrast, inward rectifying K(+) currents were present in AtKC1 knockout plants, but fundamentally altered with respect to gating and cation sensitivity. This indicates that the AtKC1 alpha-subunit represents an integral component of functional root hair K(+) uptake channels.
Reintanz
Birgit
B
Max-Delbrück-Laboratorium in der Max-Planck-Gesellschaft, Carl-von-Linné-Weg 10, 50829 Cologne, Germany.
Szyroki
Alexander
A
Ivashikina
Natalya
N
Ache
Peter
P
Godde
Matthias
M
Becker
Dirk
D
Palme
Klaus
K
Hedrich
Rainer
R
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D018408:Patch-Clamp Techniques; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D021122:Protein Subunits; D011523:Protoplasts / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D015221:Potassium Channels; D021122:Protein Subunits; D012333:RNA, Messenger; D018749:RNA, Plant; D011188:Potassium