Arabidopsis sphingolipid fatty acid 2-hydroxylases (AtFAH1 and AtFAH2) are functionally differentiated in fatty acid 2-hydroxylation and stress responses.
2-Hydroxy fatty acids (2-HFAs) are predominantly present in sphingolipids and have important physicochemical and physiological functions in eukaryotic cells. Recent studies from our group demonstrated that sphingolipid fatty acid 2-hydroxylase (FAH) is required for the function of Arabidopsis (Arabidopsis thaliana) Bax inhibitor-1 (AtBI-1), which is an endoplasmic reticulum membrane-localized cell death suppressor. However, little is known about the function of two Arabidopsis FAH homologs (AtFAH1 and AtFAH2), and it remains unclear whether 2-HFAs participate in cell death regulation. In this study, we found that both AtFAH1 and AtFAH2 had FAH activity, and the interaction with Arabidopsis cytochrome b₅ was needed for the sufficient activity. 2-HFA analysis of AtFAH1 knockdown lines and atfah2 mutant showed that AtFAH1 mainly 2-hydroxylated very-long-chain fatty acid (VLCFA), whereas AtFAH2 selectively 2-hydroxylated palmitic acid in Arabidopsis. In addition, 2-HFAs were related to resistance to oxidative stress, and AtFAH1 or 2-hydroxy VLCFA showed particularly strong responses to oxidative stress. Furthermore, AtFAH1 interacted with AtBI-1 via cytochrome b₅ more preferentially than AtFAH2. Our results suggest that AtFAH1 and AtFAH2 are functionally different FAHs, and that AtFAH1 or 2-hydroxy VLCFA is a key factor in AtBI-1-mediated cell death suppression.
Graduate School of Biological Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan.
Minoru
M
Nagano
Kentaro
K
Takahara
Masaru
M
Fujimoto
Nobuhiro
N
Tsutsumi
Hirofumi
H
Uchimiya
Maki
M
Kawai-Yamada
D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004952:Esters / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006900:Hydroxylation / Q000187:drug effects; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D018384:Oxidative Stress / Q000187:drug effects; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013107:Sphingolipids / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
D029681:Arabidopsis Proteins; D004952:Esters; D005227:Fatty Acids; D012333:RNA, Messenger; D013107:Sphingolipids; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D006899:Mixed Function Oxygenases; C575860:fatty acid 2-hydroxylase 2, Arabidopsis; C097486:CYP84A1 protein, Arabidopsis