Calmodulin interacts with MLO protein to regulate defence against mildew in barley.
In plants, defence against specific isolates of a pathogen can be triggered by the presence of a corresponding race-specific resistance gene, whereas resistance of a more broad-spectrum nature can result from recessive, presumably loss-of-regulatory-function, mutations. An example of the latter are mlo mutations in barley, which have been successful in agriculture for the control of powdery mildew fungus (Blumeria graminis f. sp. hordei; Bgh). MLO protein resides in the plasma membrane, has seven transmembrane domains, and is the prototype of a sequence-diversified family unique to plants, reminiscent of the seven-transmembrane receptors in fungi and animals. In animals, these are known as G-protein-coupled receptors and exist in three main families, lacking sequence similarity, that are thought to be an example of molecular convergence. MLO seems to function independently of heterotrimeric G proteins. We have identified a domain in MLO that mediates a Ca2+-dependent interaction with calmodulin in vitro. Loss of calmodulin binding halves the ability of MLO to negatively regulate defence against powdery mildew in vivo. We propose a sensor role for MLO in the modulation of defence reactions.
Kim
Min C
MC
Division of Applied Life Science (BK21 program), Plant Molecular Biology & Biotechnology Research Centre, Gyeongsang National University, Chinju 660-701, Korea.
Panstruga
Ralph
R
Elliott
Candace
C
Müller
Judith
J
Devoto
Alessandra
A
Yoon
Hae W
HW
Park
Hyeong C
HC
Cho
Moo J
MJ
Schulze-Lefert
Paul
P
D001203:Ascomycota / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism / Q000502:physiology*; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D005816:Genetic Complementation Test; D001467:Hordeum / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary
D002147:Calmodulin; C104922:MLO protein, Hordeum vulgare; D010940:Plant Proteins; D002118:Calcium