The Golgi Ca2+-ATPase KlPmr1p function is required for oxidative stress response by controlling the expression of the heat-shock element HSP60 in Kluyveromyces lactis.
The Golgi P-type Ca2+-ATPase, Pmr1p, is the major player for calcium homeostasis in yeast. The inactivation of KlPMR1 in Kluyveromyces lactis leads to high pleiotropic phenotypes that include reduced glycosylation, cell wall defects, and alterations of mitochondrial metabolism. In this article we found that cells lacking KlPmr1p have a morphologically altered mitochondrial network and that mitochondria (m) from Klpmr1delta cells accumulate Ca2+ more slowly and reach a lower [Ca2+]m level, when exposed to [Ca2+] < 5 microM, than wild-type cells. The Klpmr1delta cells also exhibit traits of ongoing oxidative stress and present hyperphosphorylation of KlHog1p, the hallmark for the activation of stress response pathways. The mitochondrial chaperone KlHsp60 acts as a multicopy suppressor of phenotypes that occur in cells lacking the Ca2+-ATPase, including relief from oxidative stress and recovery of cell wall thickness and functionality. Inhibition of KlPMR1 function decreases KlHSP60 expression at both mRNA and protein levels. Moreover, KlPRM1 loss of function correlates with both decreases in HSF DNA binding activity and KlHSP60 expression. We suggest a role for KlPMR1 in HSF DNA binding activity, which is required for proper KlHSP60 expression, a key step in oxidative stress response.
Uccelletti
Daniela
D
Department of Developmental and Cell Biology, University of Rome La Sapienza, 00185 Rome, Italy.
Farina
Francesca
F
Pinton
Paolo
P
Goffrini
Paola
P
Mancini
Patrizia
P
Talora
Claudio
C
Rizzuto
Rosario
R
Palleschi
Claudio
C
D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006031:Glycosylation; D006056:Golgi Apparatus / Q000502:physiology*; D007716:Kluyveromyces / Q000235:genetics / Q000502:physiology*; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D008969:Molecular Sequence Data; D009154:Mutation; D018384:Oxidative Stress; D017386:Sequence Homology, Amino Acid
D018834:Chaperonin 60; D000252:Calcium-Transporting ATPases; D002118:Calcium