The LCB2 subunit of the sphingolip biosynthesis enzyme serine palmitoyltransferase can function as an attenuator of the hypersensitive response and Bax-induced cell death.
Previous results showed that expression of the gene encoding the LONG-CHAIN BASE2 (LCB(2)) subunit of serine palmitoyltransferase (SPT), designated BcLCB(2), from nonheading Chinese cabbage (Brassica campestris ssp. chinensis) was up-regulated during hypersensitive cell death (HCD) induced by the Phytophthora boehmeriae elicitor PB90. Overexpression of BcLCB(2) in Nicotiana tabacum leaves suppressed the HCD normally initiated by elicitors and PB90-triggered H(2)O(2) accumulation. BcLCB(2) also functioned as a suppressor of mouse Bcl-2 associated X (Bax) protein-mediated HCD and cell death caused by Ralstonia solanacearum. BcLCB(2) overexpression suppressed Bax- and oxidant stress-triggered yeast cell death. Reactive oxygen species (ROS) accumulation induced by Bax was compromised in BcLCB(2)-overexpressing yeast cells. The findings that NbLCB(2) silencing in Nicotiana benthamiana enhanced elicitor-triggered HCD, combined with the fact that myriocin, a potent inhibitor of SPT, had no effect on Bax-induced programmed cell death, suggested that suppression of cell death was not involved in the dominant-negative effect that resulted from BcLCB(2) overexpression. A BcLCB(2) mutant assay showed that the suppression was not involved in SPT activity. The results suggest that plant HCD and stress-induced yeast cell death might share a common signal transduction pathway involving LCB(2), and that LCB(2) protects against cell death by inhibiting ROS accumulation, this inhibition being independent of SPT activity.
Gan
Yunzhe
Y
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Zhang
Lisha
L
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Zhang
Zhengguang
Z
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Dong
Suomeng
S
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Li
Jun
J
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Wang
Yuanchao
Y
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Zheng
Xiaobo
X
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
D000595:Amino Acid Sequence; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology; D001937:Brassica / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D016923:Cell Death / Q000502:physiology*; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions / Q000235:genetics / Q000502:physiology*; D051379:Mice; D010940:Plant Proteins; D021122:Protein Subunits; D012441:Saccharomyces cerevisiae / Q000502:physiology; D016415:Sequence Alignment; D051102:Serine C-Palmitoyltransferase / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000382:microbiology
D001425:Bacterial Outer Membrane Proteins; D010940:Plant Proteins; D021122:Protein Subunits; C075462:harpin protein, Erwinia amylovora; C053376:pathogenesis-related proteins, plant; D051102:Serine C-Palmitoyltransferase