Mitochondrial ClpX activates an essential biosynthetic enzyme through partial unfolding
- Brandeis University, United States
- Northeastern University, United States
- Massachusetts Institute of Technology, United States
Abstract
Mitochondria control the activity, quality, and lifetime of their proteins with an autonomous system of chaperones, but the signals that direct substrate-chaperone interactions and outcomes are poorly understood. We previously discovered that the mitochondrial AAA+ protein unfoldase ClpX (mtClpX) activates the initiating enzyme for heme biosynthesis, 5-aminolevulinic acid synthase (ALAS), by promoting cofactor incorporation. Here, we ask how mtClpX accomplishes this activation. Using S. cerevisiae proteins, we identified sequence and structural features within ALAS that position mtClpX and provide it with a grip for acting on ALAS. Observation of ALAS undergoing remodeling by mtClpX revealed that unfolding is limited to a region extending from the mtClpX-binding site to the active site. Unfolding along this path is required for mtClpX to gate cofactor binding to ALAS. This targeted unfolding contrasts with the global unfolding canonically executed by ClpX homologs and provides insight into how substrate-chaperone interactions direct the outcome of remodeling.
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All data generated or analysed during this study are included in the manuscript and supporting files. A source data file has been provided for Figures 4 and 5.
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Author details
Funding
National Institute of Diabetes and Digestive and Kidney Diseases (DK115558)
- Tania A Baker
Howard Hughes Medical Institute
- Tania A Baker
National Institute of Diabetes and Digestive and Kidney Diseases (DK095726)
- Julia R Kardon
National Institute of General Medical Sciences (GM101135)
- John R Engen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Kardon et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Mitochondrial ClpX activates an essential biosynthetic enzyme through partial unfolding
eLife 9:e54387.
https://doi.org/10.7554/eLife.54387
