Backbone assignment and secondary structure of the PsbQ protein from Photosystem II
Sprache des Titels:
PsbQ is one of the extrinsic proteins situated on the lumenal surface of Photosystem II (PSII) in the higher
plants and green algae. Its three-dimensional structure was determined by X-ray crystallography apart from
the residues 14?33. To obtain further details about its structure and potentially its dynamics, we approached
the problem by NMR. In this paper we report 1H, 15N, and 13C NMR assignments for the PsbQ protein. The
very challenging poly-proline stretches could be assigned using 13C-detected NMR experiments that enabled
the assignments of twelve out of the thirteen proline residues of PsbQ. The identification of PsbQ secondary
structure elements on the basis of our NMR data was accomplished with the programs TALOS+, web server
CS23D and CS-Rosetta. To obtain additional secondary structure information, three-bond HN-H? J-coupling
constants and deviation of experimental 13C? and 13C? chemical shifts from random coil values were
determined. The resulting ?consensus? secondary structure of PsbQ compares very well with the resolved regions of the published X-Ray structure and gives a first estimate of the structure of the ?missing link? (i.e.
residues 14?33), which will serve as the basis for the further investigation of the structure, dynamics and
interactions by NMR.