Research

Topics of Research

Under construction!!!

Signal transduction in the visual system of Drosophila

Effective visual system

Mutations in body pigmentation and vision

cuticle color


ERGs


[True 2005].

Enzymatic efficiencies of Ebony & Tan

[Caizzi 1987] [Hovemann 1998] [Richardt 2003] [True 2005].

Expression of the proteins Ebony & Tan in the insect eye

[Richardt 2002].

Ebony-Tan


[Wagner 2006].

Model of the transmitter cycle


Literature

Caizzi, R., Ritossa, F., Ryseck, R.-P., Richter, S. and Hovemann, B. (1987)
Characterization of the ebony locus in Drosophila melanogaster.
Mol Gen Genet. 206:66-70

Hovemann, B.T., Ryseck, R.-P., Walldorf, U., Störtkuhl, K.F., Dietzel, I.D., Dessen, E. (1998)
The Drosophila ebony gene is closely related to microbial peptide synthetases and shows specific cuticle and nervous system expression.
Gene. 221(1):1-9 Abstract

Richardt, A., Ryback, R., Störtkuhl, K.F., Meinertzhagen, I.A., and Hovemann, B.T. (2002)
The Ebony protein in the Drosophila nervous system: optic neuropile expression in glial cells.
J Comp Neurol. 452(1):93-102 Abstract Artikel

Richardt, A., Kemme, T., Wagner, S., Schwarzer, D., Marahiel, M. and Hovemann, B.T. (2003)
Ebony: A novel nonribosomal peptide synthetase for beta-alanine conjugation with biogenic amines in Drosophila.
J Biol Chem. 278(42):41160-6 Abstract Artikel

John True, Shu-Dan Yeh, Bernhard T. Hovemann, Tobias Kemme, Ian A. Meinertzhagen, Tara N. Edwards, Shian-Ren Liou, Qian Han, Jianyong Li (2005)
Drosophila tan encodes a novel hydrolase required in pigmentation and vision.
PLoS Genet. 1(5):e63 Cover Artikel Pressemitteilung

Stefanie Wagner, Christiane Heseding, Kamila Szlachta, John R. True, Heino Prinz, and Bernhard T. Hovemann (2007)
Drosophila photoreceptors express cysteine peptidase Tan.
J Comp Neurol. 500(4):601-11 Abstract Artikel

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Current publication

Visual Signal Transduction

Neurons, the cells in the brain responsible for carrying information, communicate with each other using a class of chemicals known as neurotransmitters. One family of neurotransmitters, the monoamines, includes dopamine, serotonin, and histamine, all of which play major physiological roles. However, unlike dopamine and serotonin, the regulation of the brain’s histamine content is poorly understood. We are using the fruitfly Drosophila melanogaster to study the storage and release of histamine from brain cells. Both mammals and insects use a class of proteins called transporters to store amines.

Tan provides a key function in the recycling pathway of the neurotransmitter histamine by cleavage of carcinine in the Drosophila eye. It is also involved in the process of cuticle formation. There, it cleaves beta-alanyl-dopamine, a major component in cuticle sclerotization.

Alternative tasks of Drosophila tan in neurotransmitter recycling vs cuticle sclerotization disclosed by kinetic properties


Silvia Aust, Florian Brüsselbach, Stefanie Pütz, and Bernhard T. Hovemann
J. Biol. Chem. 2010 Jul 2;285(27):20740-7

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To investigate its pleiotropic functions, we have expressed Tan as His6-fusion protein in E. coli and have purified it to homogeneity. Kinetic parameters of carcinine (B) and beta-alanyl-dopamine (A) cleavage exhibit profound differences. The Km of both substrates differ by nearly two orders of magnitude. More importantly, concentration dependence of activity reflects the necessities required by the respective cellular pathway, in which Tan is participating.

Our results show how the enzyme can manage different tasks in pleitropic functions by simply varying substrate affinity and reaction speed and extend our understanding on cuticle sclerotization and histamine neurotransmitter recycling in Drosophila.

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