ORM expression alters sphingolipid homeostasis and differentially affects ceramide synthase activity

Athen N. Kimberlin, Gongshe Han, Kyle D. Luttgeharm, Ming Chen, Rebecca E. Cahoon, Julie M Stone, Jonathan E Markham, Teresa M. Dunn, Edgar B Cahoon

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Sphingolipid synthesis is tightly regulated in eukaryotes. This regulation in plants ensures sufficient sphingolipids to support growth while limiting the accumulation of sphingolipid metabolites that induce programmed cell death. Serine palmitoyltransferase (SPT) catalyzes the first step in sphingolipid biosynthesis and is considered the primary sphingolipid homeostatic regulatory point. In this report, Arabidopsis (Arabidopsis thaliana) putative SPT regulatory proteins, orosomucoidlike proteins AtORM1 and AtORM2, were found to interact physically with Arabidopsis SPT and to suppress SPT activity when coexpressed with Arabidopsis SPT subunits long-chain base1 (LCB1) and LCB2 and the small subunit of SPT in a yeast (Saccharomyces cerevisiae) SPT-deficient mutant. Consistent with a role in SPT suppression, AtORM1 and AtORM2 overexpression lines displayed increased resistance to the programmed cell death-inducing mycotoxin fumonisin B1, with an accompanying reduced accumulation of LCBs and C16 fatty acid-containing ceramides relative to wild-type plants. Conversely, RNA interference (RNAi) suppression lines of AtORM1 and AtORM2 displayed increased sensitivity to fumonisin B1 and an accompanying strong increase in LCBs and C16 fatty acid-containing ceramides relative to wild-type plants. Overexpression lines also were found to have reduced activity of the class I ceramide synthase that uses C16 fatty acid acyl-coenzyme A and dihydroxy LCB substrates but increased activity of class II ceramide synthases that use very-long-chain fatty acyl-coenzyme A and trihydroxy LCB substrates. RNAi suppression lines, in contrast, displayed increased class I ceramide synthase activity but reduced class II ceramide synthase activity. These findings indicate that ORM mediation of SPT activity differentially regulates functionally distinct ceramide synthase activities as part of a broader sphingolipid homeostatic regulatory network.

Original languageEnglish (US)
Pages (from-to)889-900
Number of pages12
JournalPlant Physiology
Volume172
Issue number2
DOIs
StatePublished - Oct 1 2016

Fingerprint

serine C-palmitoyltransferase
Serine C-Palmitoyltransferase
sphingolipids
Sphingolipids
homeostasis
Homeostasis
Arabidopsis
acyl coenzyme A
Acyl Coenzyme A
ceramides
fumonisin B1
Fatty Acids
Ceramides
RNA Interference
fatty acids
RNA interference
Cell Death
apoptosis
sphingosine N-acyltransferase
dihydroceramide desaturase

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

Cite this

ORM expression alters sphingolipid homeostasis and differentially affects ceramide synthase activity. / Kimberlin, Athen N.; Han, Gongshe; Luttgeharm, Kyle D.; Chen, Ming; Cahoon, Rebecca E.; Stone, Julie M; Markham, Jonathan E; Dunn, Teresa M.; Cahoon, Edgar B.

In: Plant Physiology, Vol. 172, No. 2, 01.10.2016, p. 889-900.

Research output: Contribution to journalArticle

Kimberlin, Athen N. ; Han, Gongshe ; Luttgeharm, Kyle D. ; Chen, Ming ; Cahoon, Rebecca E. ; Stone, Julie M ; Markham, Jonathan E ; Dunn, Teresa M. ; Cahoon, Edgar B. / ORM expression alters sphingolipid homeostasis and differentially affects ceramide synthase activity. In: Plant Physiology. 2016 ; Vol. 172, No. 2. pp. 889-900.
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