title: Direct methods and residue type specific isotope labeling in NMR structure determination and model-driven sequential assignment.
abstract: Direct methods in NMR based structure determination start from an unassigned ensemble of unconnected gaseous hydrogen atoms. Under favorable conditions they can produce low resolution structures of proteins. Usually a prohibitively large number of NOEs is required, to solve a protein structure ab-initio, but even with a much smaller set of distance restraints low resolution models can be obtained which resemble a protein fold. One problem is that at such low resolution and in the absence of a force field it is impossible to distinguish the correct protein fold from its mirror image. In a hybrid approach these ambiguous models have the potential to aid in the process of sequential backbone chemical shift assignment when (13)C(beta) and (13)C' shifts are not available for sensitivity reasons. Regardless of the overall fold they enhance the information content of the NOE spectra. These, combined with residue specific labeling and minimal triple-resonance data using (13)C(alpha) connectivity can provide almost complete sequential assignment. Strategies for residue type specific labeling with customized isotope labeling patterns are of great advantage in this context. Furthermore, this approach is to some extent error-tolerant with respect to data incompleteness, limited precision of the peak picking, and structural errors caused by misassignment of NOEs.
authors.affiliation: Institute of Biomolecular Structural Chemistry, Max F. Perutz Laboratories, University of Vienna, Campus Vienna Biocenter 5/1, Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schedlbauer
authors.forename: Renate
authors.initials: R
authors.lastname: Auer
authors.forename: Karin
authors.initials: K
authors.lastname: Ledolter
authors.forename: Martin
authors.initials: M
authors.lastname: Tollinger
authors.forename: Karin
authors.initials: K
authors.lastname: Kloiber
authors.forename: Roman
authors.initials: R
authors.lastname: Lichtenecker
authors.forename: Simon
authors.initials: S
authors.lastname: Ruedisser
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hommel
authors.forename: Walther
authors.initials: W
authors.lastname: Schmid
authors.forename: Robert
authors.initials: R
authors.lastname: Konrat
authors.forename: Georg
authors.initials: G
authors.lastname: Kontaxis