Assessment of substrate-stabilizing factors for DnaK on the folding of aggregation-prone proteins.
Hydrophobic interactions between molecular chaperones and their nonnative substrates have been believed to be mainly responsible for both substrate recognition and stabilization against aggregation. However, the hydrophobic contact area between DnaK and its substrate proteins is very limited and other factors of DnaK for the substrate stabilization could not be excluded. Here, we covalently fused DnaK to the N-termini of aggregation-prone proteins in vivo. In the context of a fusion protein, DnaK has the ability to efficiently solubilize its linked proteins. The point mutation of the residue of DnaK critical for the substrate recognition and the deletion of the C-terminal substrate-binding domain did not have significant effect on the solubilizing ability of DnaK. The results imply that other factors of DnaK, distinct from the hydrophobic shielding of folding intermediates, also contributes to stabilization of its noncovalently bound substrates against aggregation. Elucidation of the nature of these factors would further enhance our understanding of the substrate stabilization of DnaK for expedited protein folding.
Department of Biotechnology, College of Engineering, Yonsei University, 134 Shinchon-Dong, Seodaemun-Gu, Seoul 120-749, Republic of Korea.
Kisun
K
Ryu
Chul Woo
CW
Kim
Byung Hee
BH
Kim
Kyoung Sim
KS
Han
Kyun-Hwan
KH
Kim
Seong Il
SI
Choi
Baik L
BL
Seong
D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D017354:Point Mutation; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics; D012995:Solubility
D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; C063842:dnaK protein, E coli