Ph.D. Michigan State University, 2004
E141 Beadle Center
Research in my lab focuses on using microbial eukaryotic model organisms as systems to study various aspects of lipid metabolism, including membrane lipid and fatty acid trafficking between organelles, the regulation of membrane lipid and triglyceride synthesis, and the regulation of lipid droplet assembly and morphology.
We are using the green alga Chlamydomonas reinhardtii as a unicellular plant biochemical-genetic model to identify and characterize the structural and regulatory components controlling fatty acid synthesis, transport, desaturation, and storage. Chlamydomonas is an ideal organism with which to conduct these studies given it's long (>75 years) history as a genetic model organism, fully sequenced and well annotated genome, and the open and supportive algal research community on the UNL campus. This work has many implications for the production of commercially important, lipid-derived compounds from algae, e.g. hydrocarbons for fuel, novel fatty acids for chemical feedstocks, and antioxidant pigments for cosmetics and nutraceuticals.
Another set of projects makes use of the powerful genetic, genomic, and biochemical tools in the yeast Saccharomyces cerevisiae. We are taking genomic and chemical genetic approaches to identify proteins that are involved in the trafficking of lyso-phospholipids from the plasma membrane to the endoplasmic reticulum, as well as other inter-organelle lipid transport phenomena. We also make use of the metabolic engineering resources in yeast to re-wire certain core lipid metabolic processes and study the effects of these alterations on membrane biogenesis and function. Our work on the genetics, biochemistry, and cell biology of lipid metabolism in yeast has direct implications for medically relevant research areas, such as inflammation, cell migration, cancer biology, and cardiovascular disease.
• Riekhof, W.R., Bertrand, H., Benning, C., and Voelker, D.R. (2012) Fungi replace phosphatidylcholine with a phosphorusfree betaine lipid during phosphate starvation. In preparation for re-submission to Eukaryotic Cell after initial review.
• Riekhof, W.R., Wu, W.I., Jones, J.L., Nikrad, M., Chan, M.M., Loewen, C.J.R., and Voelker, D.R. (2012) A macromolecular assembly of proteins and lipid domains regulates ER to Golgi phosphatidylserine traffic in Saccharomyces cerevisiae. In preparation for submission to the Journal of Biological Chemistry.
• Brechbuhl H.M., Gould N., Kachadourian R., Riekhof W.R., Voelker D.R., Day B.J. (2010) Glutathione transport is a unique function of the ATP-binding cassette protein ABCG2. J Biol Chem. 285, 16582-16587
• Steinhauer J., Gijón M.A., Riekhof W. R., Voelker D. R., Murphy R. C., Treisman J.E. (2009) Drosophila lysophospholipid acyltransferases are specifically required for germ cell development. Mol Biol Cell. 20, 5224-35.
• Riekhof W. R., Voelker D. R. (2009) The yeast plasma membrane P4-ATPases are major transporters for lysophospholipids. Biochim Biophys Acta. 1791, 620-7
• Riekhof, W. R., Benning, C. (2008). Glycerolipid Biosynthesis, In The Chlamydomonas Sourcebook, Second Edition, Volume II. E. H. Harris, D. B. Stern, eds., pp. 41-68.
• Gijón, M. A.*, Riekhof, W. R.*, Zarini, S., Murphy, R. M., Voelker, D. R. (2008). Lysophospholipid acyltransferases and arachidonate recycling in human neutrophils. J Biol Chem. 283, 30235-30245. *Shared first authorship.
• Riekhof, W. R., Wu, J., Gijón, M. A., Zarini, S., Murphy, R. C., and Voelker, D. R. (2007). Lysophosphatidylcholine metabolism in Saccharomyces cerevisiae: the role of P-type ATPases in transport and a broad specificity acyltransferase in acylation. J Biol Chem 282, 36853-61.
• Merchant, S. S., Prochnik, S. E., Vallon, O., Harris, E. H., et al. (2007). The Chlamydomonas genome reveals the evolution of key animal and plant functions. Science 318, 245-250.
• Riekhof, W. R., Wu, J., Jones, J. L., and Voelker, D. R. (2007). Identification and characterization of the major lysophosphatidylethanolamine acyltransferase in Saccharomyces cerevisiae. J Biol Chem 282, 28344-28352.
• Choi, J. Y., Riekhof, W. R., Wu, W. I., and Voelker, D. R. (2006). Macromolecular assemblies regulate nonvesicular phosphatidylserine traffic in yeast. Biochem Soc Trans 34, 404-408.
• Riekhof, W. R., and Voelker, D. R. (2006). Uptake and utilization of lyso-phosphatidylethanolamine by Saccharomyces cerevisiae. J Biol Chem 281, 36588-36596.
• Riekhof, W. R., Sears, B. B., and Benning, C. (2005). Annotation of genes involved in glycerolipid biosynthesis in Chlamydomonas reinhardtii: discovery of the betaine lipid synthase BTA1Cr. Eukaryot Cell 4, 242-252.
• Riekhof, W. R., Andre, C., and Benning, C. (2005). Two enzymes, BtaA and BtaB, are sufficient for betaine lipid biosynthesis in bacteria. Arch Biochem Biophys 441, 96-105.
• Weber, A. P., Oesterhelt, C., Gross, W., et al. (2004). EST-analysis of the thermo-acidophilic red microalga Galdieria sulphuraria reveals potential for lipid A biosynthesis and unveils the pathway of carbon export from rhodoplasts. Plant Mol Biol 55, 17-32.
• Riekhof, W. R., Ruckle, M. E., Lydic, T. A., Sears, B. B., and Benning, C. (2003). The sulfolipids 2'-O-acylsulfoquinovosyldiacylglycerol and sulfoquinovosyldiacylglycerol are absent from a Chlamydomonas reinhardtii mutant deleted in SQD1. Plant Physiol 133, 864-874.
• Xu, C., Fan, J., Riekhof, W. R., Froehlich, J. E., and Benning, C. (2003). A permease-like protein involved in ER to thylakoid lipid transfer in Arabidopsis. EMBO J 22, 2370-2379.
• Bilyeu, K. D., Cole, J. L., Laskey, J. G., Riekhof, W. R., Esparza, T. J., Kramer, M. D., and Morris, R. O. (2001). Molecular and biochemical characterization of a cytokinin oxidase from maize. Plant Physiol 125, 378-386.