Insights into the role and mechanism of the AAA+ adaptor Clps

Protein degradation is a vital process in cells for quality control and participation in regulatory pathways. Intracellular ATP-dependent proteases are responsible for regulated degradation and are highly controlled in their function, especially with respect to substrate selectivity. Adaptor proteins that can associate with the proteases add an additional layer of control to substrate selection. Thus, understanding the mechanism and role of adaptor proteins is a critical component to understanding how proteases choose their substrates. In this thesis, I examine the role of the intracellular protease ClpAP and its adaptor ClpS in Escherichia coli. ClpS binds to the N-terminal domain of ClpA and plays dual roles in ClpAP substrate selectivity: ClpS inhibits the degradation of some substrates such as ssrA-tagged proteins and enhances the degradation of other substrates such as N-end-rule proteins. We wished to elucidate how ClpS influences ClpAP substrate selection, and found that the stoichiometry of ClpS binding to ClpA is one level of regulation. Furthermore, we demonstrated that the N-terminal extension of ClpS is vital for the adaptor's role in delivering N-end-rule substrates to ClpAP for degradation, but this extension is not required for inhibition of ssrA-tagged proteins. Truncation studies of the ClpS N-terminal extension showed a dramatic length-dependence on N-end-rule protein delivery, and the chemical composition of this portion of ClpS also affected the ability to degrade N-degron-bearing substrates.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Hou, Jennifer Yuan

Advisor dc:contributor.advisor

• Tania A. Baker.

• Biology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/46812

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/46812