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The flexible connection of the N‐terminal domain in ClpB supports substrate binding and controls the aggregate reactivation efficiency
Author(s) -
Zhang Ting,
Ploetz Elizabeth A,
Nagy Maria,
Smith Paul E,
Zolkiewski Michal
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.907.7
Subject(s) - linker , clpb , biophysics , chemistry , chaperone (clinical) , stereochemistry , crystallography , biochemistry , biology , escherichia coli , gene , computer science , medicine , pathology , operating system
ClpB reactivates aggregated proteins in cooperation with the DnaK chaperone system. ClpB contains two nucleotide‐binding domains (NBDs) and a smaller N‐terminal domain attached to the first NBD with a 15 aa‐long unstructured linker containing a GG motif. We investigated the role of the linker in aggregate reactivation. We produced 7 variants of ClpB with modified linker sequence. To increase the linker's conformational flexibility, we extended the GG motif up to . To decrease the linker's flexibility, we deleted the GG motif and converted it into GP and PP. We found that all linker variants showed a lower aggregate reactivation rate and a lower aggregate binding capability than wt ClpB. Molecular dynamics simulations showed that all modified linkers display different end‐to‐end distributions than the wt linker. For the linkers containing multiple glycines, a lower than expected degree of conformational flexibility may be due to the transient formation of a salt bridge‐stabilized alpha‐helical segment. We conclude that the linker region supports the chaperone activity of ClpB by controlling the efficiency of substrate binding. Moreover, the length and conformational flexibility of the linker region may have been optimized during evolution to achieve the most advantageous aggregate‐removal rates. Supported by the National Institutes of Health and the Johnson Center for Basic Cancer Research at KSU.