Other Biochemistry, Biophysics, and Structural Biology Commons^™

Lipid Transport Required To Make Lipids Of Photosynthetic Membranes, Evan Labrant, Allison C. Barnes, Rebecca Roston

Department of Biochemistry: Faculty Publications

Photosynthetic membranes provide much of the usable energy for life on earth. To produce photosynthetic membrane lipids, multiple transport steps are required, including fatty acid export from the chloroplast stroma to the endoplasmic reticulum, and lipid transport from the endoplasmic reticulum to the chloroplast envelope membranes. Transport of hydrophobic molecules through aqueous space is energetically unfavorable and must be catalyzed by dedicated enzymes, frequently on specialized membrane structures. Here, we review photosynthetic membrane lipid transport to the chloroplast in the context of photosynthetic membrane lipid synthesis. We independently consider the identity of transported lipids, the proteinaceous transport components, and membrane …

Overexpression Of Patatin-Related Phospholipase Aiiiβ Altered The Content And Composition Of Sphingolipids In Arabidopsis, Maoyin Li, Jennifer E. Markham, Xuemin Wang

Department of Biochemistry: Faculty Publications

In plants, fatty acids are primarily synthesized in plastids and then transported to the endoplasmic reticulum (ER) for synthesis of most of the complex membrane lipids, including glycerolipids and sphingolipids. The first step of sphingolipid synthesis, which uses a fatty acid and a serine as substrates, is critical for sphingolipid homeostasis; its disruption leads to an altered plant growth. Phospholipase As have been implicated in the trafficking of fatty acids from plastids to the ER. Previously, we found that overexpression of a patatin-related phospholipase, pPLAIIIβ, resulted in a smaller plant size and altered anisotropic cell expansion. Here, we determined the …

Arabidopsis Accelerated Cell Death 11, Acd11, Is A Ceramide-1-Phosphate Transfer Protein And Intermediary Regulator Of Phytoceramide Levels, Dhirendra K. Simanshu, Xiuhong Zhai, David Munch, Daniel Hofius, Jennifer E. Markham, Jacek Bielawski, Alicja Bielawska, Lucy Malinina, Julian G. Molotkovsky, John W. Mundy, Dinshaw J. Patel, Rhoderick E. Brown

Department of Biochemistry: Faculty Publications

The accelerated cell death 11 (acd11) mutant of Arabidopsis provides a genetic model for studying immune response activation and localized cellular suicide that halt pathogen spread during infection in plants. Here, we elucidate ACD11 structure and function and show that acd11 disruption dramatically alters the in vivo balance of sphingolipid mediators that regulate eukaryotic-programmed cell death. In acd11 mutants, normally low ceramide-1- phosphate (C1P) levels become elevated, but the relatively abundant cell death inducer phytoceramide rises acutely. ACD11 exhibits selective intermembrane transfer of C1P and phyto-C1P. Crystal structures establish C1P binding via a surface-localized, phosphate headgroup recognition center …

Connections Between Sphingosine Kinase And Phospholipase D In The Abscisic Acid Signaling Pathway In Arabidopsis, Liang Guo, Girish Mishra, Jennifer E. Markham, Maoyin Li, Amanda Tawfall, Ruth Welti, Xuemin Wang

Department of Biochemistry: Faculty Publications

Background: Sphingosine kinase (SPHK) and phospholipaseD(PLD) produce different lipid mediators involved in abscisic acid (ABA) response.

Results: Ablation of SPHKs and PLDα1 attenuates ABA-induced production of LCBPs and PA. Phyto-S1P closes stomata in sphk1, sphk2, but not in pldα1, whereas PA closes stomata in all mutants.

Conclusion: SPHK acts upstream of PLDα1, whereas PLDα1 promotes SPHK.

Significance: The roles of lipid messengers in the ABA signaling pathway are clarified.