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http://dspace.mediu.edu.my:8181/xmlui/handle/10261/3535| Title: | The allosteric transition in DnaK probed by infrared difference spectroscopy. Concerted ATP-induced rearrangement of the substrate binding domain |
| Keywords: | DnaK Hsp70 Chaperones Allosterism Infrared Caged-nucleotides |
| Publisher: | Cold Spring Harbor Laboratory. Press |
| Description: | The biological activity of DnaK, the bacterial representative of the Hsp70 protein family, is regulated
by the allosteric interaction between its nucleotide and peptide substrate binding domains. Despite the
importance of the nucleotide-induced cycling of DnaK between substrate-accepting and releasing
states, the heterotropic allosteric mechanism remains as yet undefined. To further characterize
this mechanism, the nucleotide-induced absorbance changes in the vibrational spectrum of wild-type
DnaK was characterized. To assign the conformation sensitive absorption bands, two deletion mutants
(one lacking the C-terminal a-helical subdomain and another comprising only the N-terminal
ATPase domain), and a single-point DnaK mutant (T199A) with strongly reduced ATPase activity,
were investigated by time-resolved infrared difference spectroscopy combined with the use of cagednucleotides.
The results indicate that (1) ATP, but not ADP, binding promotes a conformational
change in both subdomains of the peptide binding domain that can be individually resolved; (2) these
conformational changes are kinetically coupled, most likely to ensure a decrease in the affinity of
DnaK for peptide substrates and a concomitant displacement of the lid away from the peptide binding
site that would promote efficient diffusion of the released peptide to the medium; and (3) the a-helical
subdomain contributes to stabilize the interdomain interface against the thermal challenge and allows
bidirectional transmission of the allosteric signal between the ATPase and substrate binding domains
at stress temperatures (428C). This work was supported by grants from the MEC (BFU2004-03452/BMC) and the University of the Basque Country (13505/2001). F.M. is supported by the I3P program. V.F.-S. is recipient of a predoctoral fellowship from the Basque Government. Peer reviewed |
| URI: | http://dspace.mediu.edu.my:8181/xmlui/handle/10261/3535 |
| Other Identifiers: | Protein Science 15(2): 223–233 (2006) 1469-896X http://hdl.handle.net/10261/3535 10.1110/ps.051732706 |
| Appears in Collections: | Digital Csic |
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