title: Backbone dynamics of the N-terminal domain in E. coli DnaJ determined by 15N- and 13CO-relaxation measurements.
abstract: The backbone dynamics of the N-terminal domain of the chaperone protein Escherichia coli DnaJ have been investigated using steady-state 1H-15N NOEs, 15N T1, T2, and T1 rho relaxation times, steady-state 13C alpha-13CO NOEs, and 13CO T1 relaxation times. Two recombinant constructs of the N-terminal domain of DnaJ have been studied. One, DnaJ(1-78), contains the most conserved "J-domain" of DnaJ, and the other, DnaJ(1-104), includes a glycine/phenylalanine rich region ("G/F" region) in addition to the "J-domain". DnaJ(1-78) is not capable of stimulating ATP hydrolysis by DnaK, despite the fact that all currently identified sites responsible for DnaJ-DnaK interaction are located in this region. DnaJ(1-104), on the other hand, retains nearly the full ATPase stimulatory activity of full length DnaJ. Recently, a structural analysis of these two molecules was presented in an effort to elucidate the origin of their functional differences [Huang, K., Flanagan, J. M., and Prestegard, J. H. (1999) Protein Science 8, 203-214]. Herein, an analysis of dynamic properties is presented in a similar effort. A generalized model-free approach with a full treatment of the anisotropic overall rotation of the proteins is used in the analysis of measured relaxation parameters. Our results show that internal motions on pico- to nanosecond time scales in the backbone of DnaJ(1-78) are reduced on the inclusion of the "G/F" region, while conformational exchange on micro- to millisecond time scales increases. We speculate that the enhanced flexibility of residues on the slow time scale upon the inclusion of the "G/F" region could be relevant to the ATPase stimulatory activity of DnaJ if an "induced-fit" mechanism applies to DnaJ-DnaK interactions.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens 30602-4712, USA.
authors.forename: K
authors.initials: K
authors.lastname: Huang
authors.forename: R
authors.initials: R
authors.lastname: Ghose
authors.forename: J M
authors.initials: JM
authors.lastname: Flanagan
authors.forename: J H
authors.initials: JH
authors.lastname: Prestegard
mesh_terms: D016880:Anisotropy; D001426:Bacterial Proteins / Q000737:chemistry*; D002247:Carbon Isotopes; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D002247:Carbon Isotopes; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009587:Nitrogen Isotopes; D010446:Peptide Fragments