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Updated: Aug 30, 2026

In vivo and in vitro Studies of Adaptor-clathrin Interaction
Published on: January 26, 2011
Targeted delivery of an ssrA-tagged substrate by the adaptor protein SspB to its cognate AAA+ protein ClpX
David A Dougan1, Eilika Weber-Ban, Bernd Bukau
1Zentrum für Molekulare Biologie Heidelberg, Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany. d.dougan@zmbh.uni-heidelberg.de
Abstract:
In the bacterial cytosol, degradation of ssrA-tagged proteins is primarily carried out by the proteolytic machine ClpXP in a process which is stimulated by a ClpX-specific adaptor protein, SspB. Here we elucidate the steps required for binding and transfer of ssrA-tagged substrates from SspB to ClpX. The N-terminal region of SspB is essential for its interaction with ssrA-tagged substrates, while a short conserved region at the C terminus of SspB interacts specifically with the N domain of ClpX. A single point mutation within the conserved C-terminal region of SspB is sufficient to abolish the SspB-mediated degradation of ssrA-tagged proteins by ClpXP. We propose that this region represents a common motif for the recognition of ClpX as the C-terminal region of SspB shares considerable homology with the other ClpX-specific adaptor protein, RssB. Through docking of SspB to the N-terminal domain of ClpX, the substrate is delivered to the substrate binding site in ClpX.
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