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16 Abstracts / Chemistry and Ph

ATP10D belongs to the P4 ATPase family of phospholipidranslocases, involved in phospholipid transfer from either the exo-lasmic or endoplasmatic reticulum(ER)/Golgi luminal site to theytoplasmic membrane leaflet. ATP10D is located in a genomicegion associated to HDL modulation in mice. C57BL/6 mice werehown to carry a stop codon in ATP10D, resulting in a truncatedrotein. On high-fat diet C57BL/6 mice easily develop obesity and

nsulin resistance. Currently we analyze the function of ATP10D intp10d deficient and transgenic C57BL/6 mice. In parallel we inves-

igate the impact of ATP10D in human adrenocortical NCI-H295Rells treated with siRNA.

On high-fat diet ATP10D deficient mice gain 20% more weighthan ATP10D transgenic mice and display significantly elevatedlucose and insulin levels. First results confirmed that ATP10Determines cytosolic membrane glucosylceramide levels in micend NCI-H295R cells. Furthermore the amount and distribution ofepatic lysophosphatidylcholine species are altered in these mice.nderlying transcriptomic and proteomic alterations indicate thatTP10D affects the PPAR� regulatory network and that ATP10D

unction is coupled to known ceramide transfer proteins and oxys-erol binding protein family members.

The disturbed cross-talk of cPLA2 and SMase generated mes-engers, affecting glucosylceramide and lysophosphatidylcholineevels, may relate to disturbed glucose and lipid metabolism ulti-

ately leading to obesity and insulin resistance.

oi:10.1016/j.chemphyslip.2010.05.050

ession 7: Plant lipids

L23

embrane lipid metabolism and trafficking during chloroplastevelopment and maintenance

ebecca Roston 1, Eric R. Moellering 1,2, Jinpeng Gao 1, Zhenang 1, Bagyalakshmi Muthan 1, Christoph Benning 1,∗

Department of Biochemistry and Molecular Biology, Michigan Stateniversity, East Lansing, MI 48824, USADepartment of Energy-Plant Research Laboratory, Michigan Stateniversity, East Lansing, MI 48824, USA

hloroplasts carry out photosynthesis and are the definingrganelle of green plant tissues. They contain one of the mostxtensive membrane systems found in nature, the photosynthetichylakoid membranes. Lipid precursors synthesized at the chloro-last envelope membranes and the endoplasmic reticulum (ER)erve in the assembly of the thylakoid membranes. This processequires extensive lipid trafficking between the envelope mem-ranes, the ER and the thylakoids. Genetic analysis in Arabidopsisas identified four proteins, TGD1-4, that are required for the trans-

er of lipid precursors from the ER to the chloroplast. TGD1 andGD3 comprise the permease and ATPase components of a pre-umed ABC transporter in the inner envelope membrane. TGD2 andGD4 are phosphatidic acid binding proteins postulated to inter-ct with the inner and outer envelope membrane, and the outernvelope membrane and the ER, respectively.

Non-phosphorous galactoglycerolipids dominate the polar lipidomposition of the photosynthetic membranes. Three classes ofalactosyltransferases associated with inner and outer chloroplastnvelopes participate in their assembly. MGD1 and DGD1 are UDP-al dependent enzymes that catalyze the synthesis of the bulk

f mono- and digalactoglycerolipids in Arabidopsis. A newly dis-overed galactolipid:galactolipid galactosyltransferase representsthird class. It is activated when plants are osmotically stressed

eading to the accumulation of oligogalactolipids. Moreover, this

f Lipids 163S (2010) S1–S18

enzyme is activated in the tgd lipid trafficking mutants. It will bediscussed how these different systems interact in the assembly andmaintenance of the photosynthetic membrane.

doi:10.1016/j.chemphyslip.2010.05.051

PL24

Prokaryotic FAD-containing oxidoreductases are novel playersin fatty acid metabolism

Anton Volkov 1, Alena Liavonchanka 1, Tomas Fiedler 2, SohailKhoshnevis 3, Piotr Neumann 3, Cornelia Goebel 1, Ralf Ficner 3,Bernd Kreikemeyer 2, Ivo Feussner 1,∗

1 Department for Plant Biochemistry, Georg-August-University, Göt-tingen, Germany2 Institute of Medical Microbiology, University Hospital Rostock, Ros-tock, Germany3 Department of Molecular Structural Biology, Georg-August-University, Göttingen, Germany

Faecal bacteria have unique metabolic pathways to catabolizepolyunsaturated fatty acids. Primary products are conjugatedlinoleic acids and hydroxy fatty acids. We have explored thecatalytic mechanism and structures of bacterial double bond iso-merase and hydroxylases by obtaining their crystal structurestogether with kinetic, spectroscopic and thermodynamic studies.We could show that this group of enzymes belong to the myosincross-reactive antigen (MCRA) protein family that is highly con-served among different bacterial species. Beside their ubiquitousoccurrence knowledge on the biochemical and physiological func-tion of MCRA proteins is scarce. Deletion of MCRA in S. pyogenesM49 caused twofold decrease in minimum inhibitory concentra-tion (MIC) against oleic acid, but increased survival of the mutantstrain in whole blood. Adherence and internalization properties tohuman keratinocytes were reduced in comparison to the wild type.Based on these results and other results we conclude that the pre-viously identified MCRA proteins play a role in virulence of at leastS. pyogenes M49.

doi:10.1016/j.chemphyslip.2010.05.052

PL25

An integrated strategy for generating lipid-based biorenewablechemicals: diversifying fatty acid synthesis with polyketide syn-thesis biocatalysts

Basil J. Nikolau

Center for Biorenewable Chemicals, Iowa State University, Ames, IA50011, USA

The chemical industry is currently reliant on a historically inex-pensive, petroleum-based carbon feedstock that generates a smallcollection of platform chemicals, from which highly efficient chem-ical conversions lead to the manufacture of a large collage ofchemical products. Given this paradigm of a common small set ofplatform chemicals being the basis of a large industry, the Cen-ter for Biorenewable Chemicals (CBiRC) is exploring the potentialof exploiting the polyketide/fatty acid biosynthetic pathways asa paradigm that targets the production of a series of platform-biorenewable chemicals. Polyketide and fatty acid biosynthesisshare a common series of biocatalytic mechanisms that reiter-

atively generate a homologous series of alkyl-chains that rangefrom chain lengths of 4-carbon atoms to greater than 30-carbonatoms. These metabolic processes share the common chemistryof having alternating carbonyl and methylene functional groups