Dataset Information

The Protein Chaperone ClpX Targets Native and Non-native Aggregated Substrates for Remodeling, Disassembly, and Degradation with ClpP.

ABSTRACT: ClpX is a member of the Clp/Hsp100 family of ATP-dependent chaperones and partners with ClpP, a compartmentalized protease, to degrade protein substrates bearing specific recognition signals. ClpX targets specific proteins for degradation directly or with substrate-specific adaptor proteins. Native substrates of ClpXP include proteins that form large oligomeric assemblies, such as MuA, FtsZ, and Dps in Escherichia coli. To remodel large oligomeric substrates, ClpX utilizes multivalent targeting strategies and discriminates between assembled and unassembled substrate conformations. Although ClpX and ClpP are known to associate with protein aggregates in E. coli, a potential role for ClpXP in disaggregation remains poorly characterized. Here, we discuss strategies utilized by ClpX to recognize native and non-native protein aggregates and the mechanisms by which ClpX alone, and with ClpP, remodels the conformations of various aggregates. We show that ClpX promotes the disassembly and reactivation of aggregated Gfp-ssrA through specific substrate remodeling. In the presence of ClpP, ClpX promotes disassembly and degradation of aggregated substrates bearing specific ClpX recognition signals, including heat-aggregated Gfp-ssrA, as well as polymeric and heat-aggregated FtsZ, which is a native ClpXP substrate in E. coli. Finally, we show that ClpX is present in insoluble aggregates and prevents the accumulation of thermal FtsZ aggregates in vivo, suggesting that ClpXP participates in the management of aggregates bearing ClpX recognition signals.

SUBMITTER: LaBreck CJ

PROVIDER: S-EPMC5415555 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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Publications

The Protein Chaperone ClpX Targets Native and Non-native Aggregated Substrates for Remodeling, Disassembly, and Degradation with ClpP.

LaBreck Christopher J CJ May Shannon S Viola Marissa G MG Conti Joseph J Camberg Jodi L JL

Frontiers in molecular biosciences 20170504

ClpX is a member of the Clp/Hsp100 family of ATP-dependent chaperones and partners with ClpP, a compartmentalized protease, to degrade protein substrates bearing specific recognition signals. ClpX targets specific proteins for degradation directly or with substrate-specific adaptor proteins. Native substrates of ClpXP include proteins that form large oligomeric assemblies, such as MuA, FtsZ, and Dps in <i>Escherichia coli</i>. To remodel large oligomeric substrates, ClpX utilizes multivalent tar ...[more]

PMID: 28523271

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Project description:Transcription of the clpP-clpX operon of Escherichia coli leads to the production of two different sizes of transcripts. In log phase, the level of the longer transcript is higher than the level of the shorter transcript. Soon after the onset of carbon starvation, the level of the shorter transcript increases significantly, and the level of the longer transcript decreases. The longer transcript consists of the entire clpP-clpX operon, whereas the shorter transcript contains the entire clpP gene but none of the clpX coding sequence. The RpoH protein is required for the increase in the level of the shorter transcript during carbon starvation. Primer extension experiments suggest that there is increased usage of the sigma(32)-dependent promoter of the clpP-clpX operon within 15 min after the start of carbon starvation. Expression of the clpP-clpX operon from the promoters upstream of the clpP gene decreases to a very low level by 20 min after the onset of carbon starvation. Various pieces of evidence suggest, though they do not conclusively prove, that production of the shorter transcript may involve premature termination of the longer transcript. The half-life of the shorter transcript is much less than that of the longer transcript during carbon starvation. E. coli rpoB mutations that affect transcription termination efficiency alter the ratio of the shorter clpP-clpX transcript to the longer transcript. The E. coli rpoB3595 mutant, with an RNA polymerase that terminates transcription with lower efficiency than the wild type, accumulates a lower percentage of the shorter transcript during carbon starvation than does the isogenic wild-type strain. In contrast, the rpoB8 mutant, with an RNA polymerase that terminates transcription with higher efficiency than the wild type, produces a higher percentage of the shorter clpP-clpX transcript when E. coli is in log phase. These and other data are consistent with the hypothesis that the shorter transcript results from premature transcription termination during production of the longer transcript.

Dataset Information

The Protein Chaperone ClpX Targets Native and Non-native Aggregated Substrates for Remodeling, Disassembly, and Degradation with ClpP.

Publications

The Protein Chaperone ClpX Targets Native and Non-native Aggregated Substrates for Remodeling, Disassembly, and Degradation with ClpP.

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