Martin Luther University Halle-Wittenberg


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Oxidases and aconitases

in the phytopathogenic bacterium Xanthomonas campestris pv. vesicatoria

Xanthomonas campestris pv. vesicatoria (Xcv) is an obligate aerobic bacterium that is the causal agent of bacterial spot disease on pepper and tomato plants. In order to become pathogenic, the bacterium must first and foremost be able to grow and survive in the plant apoplast, where it is naturally found. Therefore, we are interested in understanding how it achieves balanced growth in this compartment. The bacterium cannot grow in the absence of oxygen and therefore it synthesiszes an array of five different terminal oxidases, allowing it to survive under highly variable oxygen concentrations.  It also synthesizes three aconitases, which catalyze conversion of citrate to isocitrate in the TCA cycle. These aconitases are supplied with substrate via metabolism or through the action of two citrate transporters. Primarily we are interested in understanding the interplay between the different oxidases and how their synthesis affects each other in response to the prevailing oxygen levels. Similarly, we would like to understand how the function of the aconitases influences metabolism.  A common link between the oxidases and the aconitases is their requirement for iron and we are interested in determining how iron homeostasis is achieved and maintained in Xcv.