The Arabidopsis P4-ATPase ALA3 localizes to the golgi and requires a beta-subunit to function in lipid translocation and secretory vesicle formation.
Vesicle budding in eukaryotes depends on the activity of lipid translocases (P(4)-ATPases) that have been implicated in generating lipid asymmetry between the two leaflets of the membrane and in inducing membrane curvature. We show that Aminophospholipid ATPase3 (ALA3), a member of the P(4)-ATPase subfamily in Arabidopsis thaliana, localizes to the Golgi apparatus and that mutations of ALA3 result in impaired growth of roots and shoots. The growth defect is accompanied by failure of the root cap to release border cells involved in the secretion of molecules required for efficient root interaction with the environment, and ala3 mutants are devoid of the characteristic trans-Golgi proliferation of slime vesicles containing polysaccharides and enzymes for secretion. In yeast complementation experiments, ALA3 function requires interaction with members of a novel family of plant membrane-bound proteins, ALIS1 to ALIS5 (for ALA-Interacting Subunit), and in this host ALA3 and ALIS1 show strong affinity for each other. In planta, ALIS1, like ALA3, localizes to Golgi-like structures and is expressed in root peripheral columella cells. We propose that the ALIS1 protein is a beta-subunit of ALA3 and that this protein complex forms an important part of the Golgi machinery required for secretory processes during plant development.
Poulsen
Lisbeth Rosager
LR
Danish National Research Foundation, University of Copenhagen, DK-1871 Frederiksberg C, Denmark.
López-Marqués
Rosa Laura
RL
McDowell
Stephen C
SC
Okkeri
Juha
J
Licht
Dirk
D
Schulz
Alexander
A
Pomorski
Thomas
T
Harper
Jeffrey F
JF
Palmgren
Michael Gjedde
MG
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D006056:Golgi Apparatus / Q000378:metabolism*; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D022142:Secretory Vesicles / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D010743:Phospholipids; D000251:Adenosine Triphosphatases