Name: Jon Clayton (24.02.69) Position: Post-doctoral research fellow (Oct 1993 - Dec 1997) Qualifications: D. Phil. Biology University of York (1994) B. S.c. (Hons. Genetics) First Class University of York (1990)

Current address:

Current Research:

In vitro and in vivo studies of Drosophila Troponin-H.

The fruitfly (Drosophila melanogaster) provides an excellent system in which to study the structure and function of striated muscle. Unlike vertebrate muscles, Drosophila fibrillar flight muscle only becomes fully active when given a short stretch (stretch activation). In nature this feature is necessary so that the fly can achieve the high contraction frequencies (~220 Hz) necessary to power flight. In the laboratory, stretch activation is exploited in mechanical experiments to give precise control of muscle contraction.

Several mechanisms have been proposed for stretch activation including the presence of molecular stretch sensors. The "heavy" component of insect troponin (Troponin-H) is one such possible stretch sensor. In conjunction with Drs. K. Leonard and B. Bullard, I am investigating the function of Drosophila Troponin-H at the molecular level using both recombinant DNA and classical genetic techniques.

We have over-expressed full length Troponin-H (34) in bacteria and purified it to near homogeneity. The purified protein is an alpha-helical dimer which can be induced to form, helical, ladder-like para-crystals. Unfortunately we have been unable to unequivicably demonstrate binding of the purified protein to other muscle components - this work is still continuing.

We are also investigating Troponin-H's function in vivo. This is being persued in two ways: firstly by studying muscle fibres from which Troponin-H has been removed by selective proteolysis, and secondly by selecting for Troponin-H mutants. When Troponin-H is removed from muscle fibres a 35kDa protein is released from the thin filaments into the cytosol. We have determined by protein sequencing that this protein is a Glutathione S-transferase related protein (GST-2).

Related publications:

Clayton, J. D., Cripps, R. M., Sparrow, J. C. & Bullard, B. (1998)  Interaction of Troponin-H and Glutathione S-transferase-2 in the indirect flight muscles of Drosophila melanogaster. J. Muscle. Res. Cell Motil. 19; 00-00  Abstract

Ashman, K., Houthaeve, T., Clayton, J., Wilm, M., Podteleznikov, A., Jensen, O. N. & Mann, M. (1997) Application of robotics and mass spectrometry to the characterisation of the Drosophila melanogaster indirect flight muscle proteome. Letts. Peptide Science 4; 57-65  Abstract