PMID:14967151
| Citation |
Bolon, DN, Wah, DA, Hersch, GL, Baker, TA and Sauer, RT (2004) Bivalent tethering of SspB to ClpXP is required for efficient substrate delivery: a protein-design study. Mol. Cell 13:443-9 |
|---|---|
| Abstract |
SspB homodimers deliver ssrA-tagged substrates to ClpXP for degradation. SspB consists of a substrate binding domain and an unstructured tail with a ClpX binding module (XB). Using computational design, we engineered an SspB heterodimer whose subunits did not form homodimers. Experiments with the designed molecule and variants lacking one or two tails demonstrate that both XB modules are required for strong binding and efficient substrate delivery to ClpXP. Assembly of stable SspB-substrate-ClpX delivery complexes requires the coupling of weak tethering interactions between ClpX and the SspB XB modules as well as interactions between ClpX and the substrate degradation tag. The ClpX hexamer contains three XB binding sites, one per N domain dimer, and thus binds strongly to just one SspB dimer at a time. Because different adaptor proteins use the same tethering sites in ClpX, those which employ bivalent tethering, like SspB, will compete more effectively for substrate delivery to ClpXP. |
| Links | |
| Keywords |
Adenosine Triphosphatases/chemistry; Adenosine Triphosphatases/metabolism; Bacterial Proteins/chemistry; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Binding Sites/physiology; Carrier Proteins/chemistry; Carrier Proteins/genetics; Carrier Proteins/metabolism; Computer-Aided Design; Dimerization; Endopeptidase Clp; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Haemophilus influenzae/genetics; Mutagenesis, Site-Directed; Peptide Fragments/chemistry; Peptide Fragments/genetics; Peptide Fragments/metabolism; Protein Binding/physiology; Protein Engineering/methods; Protein Structure, Tertiary/physiology; Serine Endopeptidases/chemistry; Serine Endopeptidases/metabolism |
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