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Characterization of the HslU chaperone affinity for HslV protease
Author(s) -
Azim M. Kamran,
Goehring Walter,
Song Hyun Kyu,
Ramachandran Ravishankar,
Bochtler Matthias,
Goettig Peter
Publication year - 2005
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.04970405
Subject(s) - chaperone (clinical) , protease , chemistry , biochemistry , computational biology , biophysics , enzyme , biology , medicine , pathology
The HslVU complex is a bacterial two‐component ATP‐dependent protease, consisting of HslU chaperone and HslV peptidase. Investigation of protein–protein interactions using SPR in Escherichia coli HslVU and the protein substrates demonstrates that HslU and HslV have moderate affinity (Kd = 1 μM) for each other. However, the affinity of HslU for HslV fivefold increased (Kd ∼0.2 μM) after binding with the MBP∼SulA protein indicating the formation of a “ternary complex” of HslV–HslU–MBP∼SulA. The molecular interaction studies also revealed that HslU strongly binds to MBP∼SulA with 10 −9 M affinity but does not associate with nonstructured casein. Conversely, HslV does not interact with the MBP–SulA whereas it strongly binds with casein (Kd = 0.2 μM) requiring an intact active site of HslV. These findings provide evidence for “substrate‐induced” stable HslVU complex formation. Presumably, the binding of HslU to MBP∼SulA stimulates a conformational change in HslU to a high‐affinity form for HslV.