Role of SGT1 in resistance protein accumulation in plant immunity

EMBO J. 2006 May 3;25(9):2007-16. doi: 10.1038/sj.emboj.7601084. Epub 2006 Apr 13.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / immunology*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Arabidopsis Proteins / physiology*
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cell Cycle Proteins / physiology*
  • Indoleacetic Acids / metabolism
  • Indoleacetic Acids / pharmacology
  • Nuclear Proteins / analysis
  • Nuclear Proteins / metabolism
  • Plant Diseases / genetics*
  • Plant Diseases / microbiology
  • Plant Leaves / chemistry
  • Plant Leaves / metabolism
  • Plant Proteins / analysis
  • Plant Proteins / genetics
  • Plant Proteins / physiology*
  • Protein Structure, Tertiary / genetics
  • Pseudomonas syringae
  • Seeds / genetics
  • Seeds / metabolism
  • Sequence Deletion
  • Tobacco / genetics
  • Tobacco / immunology*
  • Tobacco / metabolism


  • Arabidopsis Proteins
  • Cell Cycle Proteins
  • Indoleacetic Acids
  • Nuclear Proteins
  • Plant Proteins
  • SGT1a protein, Arabidopsis
  • SGT1b protein, Arabidopsis