TAILIEUCHUNG - Báo cáo khoa học: C-mannosylation in the hypertrehalosaemic hormone from the stick insect Carausius morosus

The hypertrehalosaemic hormone from the stick insectCarausius morosus (Cam-HrTH) contains a hexose covalently bound to the ring of the trypto-phan, which is in the eighth position in the molecule. We show by solution NMR spectroscopy that the tryptophan is modified at its C d1 (C2) by an a-mannopyranose. | ỊFEBS Journal C-mannosylation in the hypertrehalosaemic hormone from the stick insect Carausius morosus Claudia E. Munte1 Gerd Gade2 Barbara Domogalla1 Werner Kremer1 Roland Kellner3 and Hans R. Kalbitzer1 1 Institute of Biophysics and PhysicalBiochemistry University of Regensburg Germany 2 Department of Zoology University of Cape Town Rondebosch South Africa 3 Target Research and Biotechnology Merck KGaA Darmstadt Germany Keywords Carausius morosus hypertrehalosaemic hormone NMR protein C-mannosylation a-mannosyltryptophan Correspondence H. R. Kalbitzer Institute for Biophysics and PhysicalBiochemistry University of Regensburg D-93040 Regensburg Germany Fax 49 941 943 2479 Tel 49 941 943 2595 E-mail . Received 7 November 2007 revised 13 December 2007 accepted 8 January 2008 doi The hypertrehalosaemic hormone from the stick insect Carausius morosus Cam-HrTH contains a hexose covalently bound to the ring of the tryptophan which is in the eighth position in the molecule. We show by solution NMR spectroscopy that the tryptophan is modified at its CS1 C2 by an a-mannopyranose. It is the first insect hormone to exhibit C-glycosylation whose exact nature has been determined experimentally. Chemical shift analysis reveals that the unmodified as well as the mannosylated Cam-HrTH are not completely random-coil in aqueous solution. Most prominently C-mannosylation strongly influences the average orientation of the tryptophan ring in solution and stabilizes it in a position clearly different from that found in the unmodified peptide. NMR diffusion measurements indicate that mannosylation reduces the effective hydrodynamic radius. It induces a change of the average peptide conformation that also diminishes the propensity for aggregation of the peptide. In insects peptidergic regulation by neuropeptides is the most important form of communication to control not only growth development and .

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