One Carbon Metabolism
In collaboration with Andrew Hanson (U. FL, Gainesville) we are studying the function of non-photosynthetic one-carbon genes. This involves the integration of biochemical, molecular biological, metabolic modeling and analytical expertise. NMR has thus far contributed to testing model-generated hypotheses about glycine betaine metabolism, to identifying the function of a putative pipecolinate oxidase and to identifying the product of p-aminobenzoate metabolism in plants. We are currently studying the function of 5-Formyl-THF cycloligase in arabdopsis. The network of non-photosynthetic one carbon metabolism in plants showing the location of genes whose function is being studied and the sources and sinks for labeled one carbon units.
Adapted from Collakova et al 2008
Aquaporins and Pollen Tip Growth
Aquaporins are proteins found in bacterial, plant, fungal and animal cells and increase the permeability of the membranes to water and/or small neutral solutes. This permeabilization of membranes is believed to be their prime function. We have analyzed the need for such increased permeabilities by examining the results of genetic knockouts, making simple calculations about water flow and by considering where aquaporins are and are not found naturally. We concluded that in a range of situations at the cellular, subcellular and tissue levels the simple permeability hypothesis cannot satisfactorily account for the presence of aquaporins. We have proposed that they may serve instead as osmosensors. Working together with collaborators in England we’re studying osmosensing and aquaporins using modeling and experiments of cell tip growth.
Tip growth of tubular cells such as pollen tubes, root hairs, filamentous fungal hyphae, filamentous actinomycetes, and some algae is found among the fastest growing cells in their respective kingdoms. Such growth is driven by internal hydrostatic pressure generated by the entry of water down an osmotic gradient. The pollen tube, which often has to grow over several centimeters through the style in order to perform its function of fertilizing an egg cell, is a long-standing model for cellular tip growth. Coordination of the rate of cell wall deposition and hydrostatic pressure is essential for tip growth and makes this an attractive system for modeling and experiments on osmosensing and water movement.