ClpXP protease

Neher, S. B., Sauer, R. T., and Baker, T. A. Distinct peptide signals in the UmuD and UmuD subunits of UmuD/D mediate tethering and substrate processing by the ClpXP protease. Proc Natl Acad Sd USA 2003, 100, 13219-24. 

In every case, the chaperone substrates for ClpA and ClpX are also substrates for degradation by the respective ClpAP or ClpXP protease. For example, ClpXP degrades MuA, and ClpAP degrades RepA (Levchenko et al., 1995 Wickner et al., 1994). Thus the specificity of protein recognition resides on the ATPase component. 

Although extensive biochemical data on both the bacterial and eukaryotic ATP-dependent proteases are available, the characterization of these proteolytic machines at atomic resolution has proven difficult, because of both the large size of these complexes and their lability to proteolysis and dissociation. No structural data at all are currently available for Lon and the mitochondrial ATP-dependent proteases. In the case of the cytosolic, membrane-integrated bacterial protease FtsH, atomic resolution data are available only for the ATPase domain (Krzywda et al. 2002 Niwa et al. 2002). In contrast, the ATP-dependent activators of the ClpAP and ClpXP proteolytic machines have so far resisted crystallization. Atomic resolution data are available only for the proteolytic component ClpP (Wang et al. 1997), and separately for a ClpX monomer (Kim and Kim 2003) and a ClpA monomer (Guo et al. 2002b). 

Steven, A. C., and Maueizi, M. R. Enzymatic and structural similarities between the Escherichia coli ATP-dependent proteases, ClpXP and ClpAP. J. Biol. Chem. 1998, 273, 12476-12481. 

Gottesman, S., Roche, E., Zhou, Y., and Sauer, R.T. (1998) The ClpXP and ClpAP proteases degrade proteins with carboxy-terminal peptide tails added by the SsrA-tagging system. Genes Dev, 12 (9), 1338-1347. 

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