Kinetics and structural analysis of Ebony, a glial protein in the visual system of Drosophila

• Applicant: Professor Dr. Bernhard T. Hovemann
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2009 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 146781222

In the visual system of arthropods histamine (HA) is the neurotransmitter for stimulus transmission from retina photoreceptor neurons to downstream postsynaptic neurons. We propose a recycling pathway for this neurotransmitter in Drosophila melanogaster (D. melanogaster) in which the two enzymes Ebony and Tan together with yet to be identified transporters hold key functions: HA from the synaptic cleft is fused to β-alanine by Ebony in the surrounding epithelial glia for inactivation. After transfer into photoreceptor neurons, β-alanyl-histamine or carcinine (CA) is hydrolyzed by Tan thereby replenishing the HA pool for vesicle loading. This working model strongly depends among others on the cata-lytic efficiency of Ebony. To verify the proposed recycling pathway with a key function of Ebony in neurotransmitter inactivation, it is essential to determine its reaction kinetics. Furthermore, enzyme structure will be solved to understand how specific recruitment of β-alanine and peptide bond formation can be performed in concert with fast HA transport into epithelial glia. As a prerequisite new expression systems and purification strategies will be employed that overcome the hitherto limited capability in preparing pure and active Ebony protein.

• DFG Programme: Research Grants