Structural study of Thermoplasma acidophilum protein TA1019 by NMR spectroscopy
A. Pavelková1, P. Macek1, J. Chmelík1, L. Žídek1 and V. Sklenář1
1National Centre for Biomolecular Research, Faculty of Science,
Masaryk University, Kotlářská 2, Brno, 611 37
TA1019 is a protein possibly involved in molybdopterin synthesis. It consists of 107 amino acid residues. Structural study of TA1019 represents a part of proteomic project of prokaryote organism, Thermoplasma acidophilum. The recombinant protein TA1019 was prepared at the University of Toronto, Canada, by Adelinda Yee and coworkers. Aggregation and low stability of the sample excluded this project from automatically performed structural investigation.
As the first step in the course of structural determination process, assignment of the measured frequencies to the individual atoms of the protein molecule has been carried out. Most of backbone resonances of the native part of the protein were assigned from a set of triple resonance experiments including HNCA, HN(CO)CA, HNCACB and CBCA(CO)NH, together with C,N-edited NOESY. Side chain resonances were assigned using the HCCH-TOCSY spectrum.
The secondary structure was predicted based on backbone atom chemical shifts. Inter-proton distances from the NOESY spectra and torsion angles φ and ψ from the predicted secondary structure served as restraints in molecular dynamics structure calculations. The calculated structure is presented and compared to a structurally related protein (sharing 40% sequence identity).