Backbone dynamics of reduced plastocyanin from the cyanobacterium Anabaena variabilis: Regions involved in electron transfer have enhanced mobility

L.X. Ma, M.A.S. Hass, N. Vierick, S.M. Kristensen, Jens Ulstrup, J.J. Led

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the N-15 and C-13(alpha) R-1 and R-2) relaxation rates and steady-state [H-1]-N-15 and [H-1]-C-13 nuclear Overhauser effects (NOEs) using the model-free approach. The C-13 relaxation studies were performed using C-13 in natural abundance. Overall, it is found that the protein backbone is rigid. However, the regions that are important for the function of the protein show moderate mobility primarily on the microsecond to millisecond time scale. These regions are the "northern" hydrophobic site close to the metal site, the metal site itself, and the "eastern" face of the molecule. In particular, the mobility of the latter region is interesting in light of recent findings indicating that residues also on the eastern face of plastocyanins from prokaryotes are important for the function of the protein. The study also demonstrates that relaxation rates and NOEs of the C-13(alpha) nuclei of proteins are valuable supplements to the conventional N-15 relaxation measurements in studies of protein backbone dynamics.
Original languageEnglish
JournalBiochemistry
Volume42
Issue number2
Pages (from-to)320-330
ISSN0006-2960
Publication statusPublished - 2003

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