Role of SGT1 in resistance protein accumulation in plant immunity.
A highly conserved eukaryotic protein SGT1 binds specifically to the molecular chaperone, HSP90. In plants, SGT1 positively regulates disease resistance conferred by many Resistance (R) proteins and developmental responses to the phytohormone, auxin. We show that silencing of SGT1 in Nicotiana benthamiana causes a reduction in steady-state levels of the R protein, Rx. These data support a role of SGT1 in R protein accumulation, possibly at the level of complex assembly. In Arabidopsis, two SGT1 proteins, AtSGT1a and AtSGT1b, are functionally redundant early in development. AtSGT1a and AtSGT1b are induced in leaves upon infection and either protein can function in resistance once a certain level is attained, depending on the R protein tested. In unchallenged tissues, steady-state AtSGT1b levels are at least four times greater than AtSGT1a. While the respective tetratricopeptide repeat (TPR) domains of SGT1a and SGT1b control protein accumulation, they are dispensable for intrinsic functions of SGT1 in resistance and auxin responses.
Azevedo
Cristina
C
The Sainsbury Laboratory, John Innes Centre, Norwich, UK.
Betsuyaku
Shigeyuki
S
Peart
Jack
J
Takahashi
Akira
A
Noël
Laurent
L
Sadanandom
Ari
A
Casais
Catarina
C
Parker
Jane
J
Shirasu
Ken
K
D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D007210:Indoleacetic Acids / Q000378:metabolism / Q000494:pharmacology; D009687:Nuclear Proteins / Q000032:analysis / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D010940:Plant Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D044224:Pseudomonas syringae; D012639:Seeds / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D014026:Nicotiana / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D007210:Indoleacetic Acids; D009687:Nuclear Proteins; D010940:Plant Proteins; C452191:SGT1a protein, Arabidopsis; C452192:SGT1b protein, Arabidopsis