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Lin CH, Tsai CH, Chou CC, Wu WF. A Transient π-π or Cation-π Interaction between Degron and Degrader Dual Residues: A Key Step for the Substrate Recognition and Discrimination in the Processive Degradation of SulA by ClpYQ (HslUV) Protease in Escherichia coli. Int J Mol Sci 2023; 24:17353. [PMID: 38139184 PMCID: PMC10743992 DOI: 10.3390/ijms242417353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/06/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The Escherichia coli ATP-dependent ClpYQ protease constitutes ClpY ATPase/unfoldase and ClpQ peptidase. The Tyr91st residue within the central pore-I site of ClpY-hexamer is important for unfolding and translocating substrates into the catalytic site of ClpQ. We have identified the degron site (GFIMRP147th) of SulA, a cell-division inhibitor recognized by ClpYQ and that the Phe143rd residue in degron site is necessary for SulA native folded structure. However, the functional association of this degron site with the ClpYQ degrader is unknown. Here, we investigated the molecular insights into substrate recognition and discrimination by the ClpYQ protease. We found that the point mutants ClpYY91FQ, ClpYY91HQ, and ClpYY91WQ, carrying a ring structure at the 91st residue of ClpY, efficiently degraded their natural substrates, evidenced by the suppressed bacterial methyl-methane-sulfonate (MMS) sensitivity, the reduced β-galactosidase activity of cpsB::lacZ, and the lowest amounts of MBP-SulA in both in vivo and in vitro degradation analyses. Alternatively, mimicking the wild-type SulA, SulAF143H, SulAF143K and SulAF143W, harboring a ring structure or a cation side-group in 143rd residue of SulA, were efficiently degraded by ClpYQ in the bacterial cells, also revealing shorter half-lives at 41 °C and higher binding affinities towards ClpY in pull-down assays. Finally, ClpYY91FQ and ClpYY91HQ, were capable of effectively degrading SulAF143H and SulAF143K, highlighting a correspondingly functional interaction between the SulA 143rd and ClpY 91st residues. According to the interchangeable substituted amino acids, our results uniquely indicate that a transient π-π or cation-π interaction between the SulA 143rd and ClpY 91st residues could be aptly gripped between the degron site of substrates and the pore site of proteases (degraders) for substrate recognition and discrimination of the processive degradation.
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Affiliation(s)
- Chu-Hsuan Lin
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei 10617, Taiwan
| | - Chih-Hsuan Tsai
- Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan 701401, Taiwan
| | - Chun-Chi Chou
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei 10617, Taiwan
| | - Whei-Fen Wu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei 10617, Taiwan
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2
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McGuire BE, Nano FE. Whole-genome sequencing analysis of two heat-evolved Escherichia coli strains. BMC Genomics 2023; 24:154. [PMID: 36973666 PMCID: PMC10044804 DOI: 10.1186/s12864-023-09266-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND High temperatures cause a suite of problems for cells, including protein unfolding and aggregation; increased membrane fluidity; and changes in DNA supercoiling, RNA stability, transcription and translation. Consequently, enhanced thermotolerance can evolve through an unknown number of genetic mechanisms even in the simple model bacterium Escherichia coli. To date, each E. coli study exploring this question resulted in a different set of mutations. To understand the changes that can arise when an organism evolves to grow at higher temperatures, we sequenced and analyzed two previously described E. coli strains, BM28 and BM28 ΔlysU, that have been laboratory adapted to the highest E. coli growth temperature reported to date. RESULTS We found three large deletions in the BM28 and BM28 ΔlysU strains of 123, 15 and 8.5 kb in length and an expansion of IS10 elements. We found that BM28 and BM28 ΔlysU have considerably different genomes, suggesting that the BM28 culture that gave rise to BM28 and BM28 ΔlysU was a mixed population of genetically different cells. Consistent with published findings of high GroESL expression in BM28, we found that BM28 inexplicitly carries the groESL bearing plasmid pOF39 that was maintained simply by high-temperature selection pressure. We identified over 200 smaller insertions, deletions, single nucleotide polymorphisms and other mutations, including changes in master regulators such as the RNA polymerase and the transcriptional termination factor Rho. Importantly, this genome analysis demonstrates that the commonly cited findings that LysU plays a crucial role in thermotolerance and that GroESL hyper-expression is brought about by chromosomal mutations are based on a previous misinterpretation of the genotype of BM28. CONCLUSIONS This whole-genome sequencing study describes genetically distinct mechanisms of thermotolerance evolution from those found in other heat-evolved E. coli strains. Studying adaptive laboratory evolution to heat in simple model organisms is important in the context of climate change. It is important to better understand genetic mechanisms of enhancing thermotolerance in bacteria and other organisms, both in terms of optimizing laboratory evolution methods for various organisms and in terms of potential genetic engineering of organisms most at risk or most important to our societies and ecosystems.
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Affiliation(s)
- Bailey E McGuire
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, B.C, Canada.
| | - Francis E Nano
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, B.C, Canada
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Xie ZX, Yan KQ, Kong LF, Gai YB, Jin T, He YB, Wang YY, Chen F, Lin L, Lin ZL, Xu HK, Shao ZZ, Liu SQ, Wang DZ. Metabolic tuning of a stable microbial community in the surface oligotrophic Indian Ocean revealed by integrated meta-omics. MARINE LIFE SCIENCE & TECHNOLOGY 2022; 4:277-290. [PMID: 37073226 PMCID: PMC10077294 DOI: 10.1007/s42995-021-00119-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 08/25/2021] [Indexed: 05/03/2023]
Abstract
Understanding the mechanisms, structuring microbial communities in oligotrophic ocean surface waters remains a major ecological endeavor. Functional redundancy and metabolic tuning are two mechanisms that have been proposed to shape microbial response to environmental forcing. However, little is known about their roles in the oligotrophic surface ocean due to less integrative characterization of community taxonomy and function. Here, we applied an integrated meta-omics-based approach, from genes to proteins, to investigate the microbial community of the oligotrophic northern Indian Ocean. Insignificant spatial variabilities of both genomic and proteomic compositions indicated a stable microbial community that was dominated by Prochlorococcus, Synechococcus, and SAR11. However, fine tuning of some metabolic functions that are mainly driven by salinity and temperature was observed. Intriguingly, a tuning divergence occurred between metabolic potential and activity in response to different environmental perturbations. Our results indicate that metabolic tuning is an important mechanism for sustaining the stability of microbial communities in oligotrophic oceans. In addition, integrated meta-omics provides a powerful tool to comprehensively understand microbial behavior and function in the ocean. Supplementary Information The online version contains supplementary material available at 10.1007/s42995-021-00119-6.
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Affiliation(s)
- Zhang-Xian Xie
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, 361005 China
- College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005 China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Zhuhai, 519082 China
| | - Ke-Qiang Yan
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, 518083 China
| | - Ling-Fen Kong
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, 361005 China
| | - Ying-Bao Gai
- Key Laboratory of Marine Genetic Resources, Third Institute of Oceanography, Ministry of Natural Resources of China, Xiamen, 361005 China
- State Key Laboratory Breeding Base of Marine Genetic Resources/Fujian Key Laboratory of Marine Genetic Resources, Xiamen, 361005 China
| | - Tao Jin
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
| | - Yan-Bin He
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
| | - Ya-Yu Wang
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
| | - Feng Chen
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD 21202 USA
| | - Lin Lin
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, 361005 China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Zhuhai, 519082 China
| | - Zhi-Long Lin
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
| | - Hong-Kai Xu
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
- BGI Education Center, University of Chinese Academy of Sciences, Shenzhen, 518083 China
| | - Zong-Ze Shao
- Key Laboratory of Marine Genetic Resources, Third Institute of Oceanography, Ministry of Natural Resources of China, Xiamen, 361005 China
- State Key Laboratory Breeding Base of Marine Genetic Resources/Fujian Key Laboratory of Marine Genetic Resources, Xiamen, 361005 China
| | - Si-Qi Liu
- BGI-Shenzhen, Beishan Industrial Zone 11th Building, Shenzhen, 518083 China
| | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, 361005 China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Zhuhai, 519082 China
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Dong S, Chen H, Zhou Q, Liao N. Protein degradation control and regulation of bacterial survival and pathogenicity: the role of protein degradation systems in bacteria. Mol Biol Rep 2021; 48:7575-7585. [PMID: 34655017 DOI: 10.1007/s11033-021-06744-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Protein degradation systems play crucial roles in all the kingdoms of life. Their natural function is to eliminate proteins that are improperly synthesized, damaged, aggregated, or short-lived, ensuring the timely and accurate regulation of the response to abrupt environmental changes. Thus, proteolysis plays an important role in protein homeostasis, quality control, and the control of regulatory processes, such as adaptation and cell development. Except for the lysosome, ATPases Associated with various cellular Activities (AAA+) ATPase-protease complex is another major protein degradation system in the cell. METHODS AND RESULTS The AAA+ ATPase-protease complex is a giant energy-dependent protease complex found in almost all kinds of cells, including bacteria, archaea and eukarya. Based on sequence analysis of ClpQ (HslV) and 20S proteasome beta subunits, it was found that bacterial ClpQ possess multiple same highly conserved motifs with 20S proteasome beta subunits of archaea and eukaryote. In this review, we also discussed the structure and functional mechanism, protein degradation signals and pathogenic role of proteasome / Clp protease complex in prokaryotes. CONCLUSION Bacterial protein degradation systems play important roles in stress tolerance, protein quality control, DNA protection, transcription and pathogenicity of bacteria. But our current knowledge of the bacterial protease system is incomplete, and further research into the Clp protease complex and associated protein degradation signals will extend our understanding of the metabolism, physiology, reproduction, and pathogenicity of bacteria.
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Affiliation(s)
- Shilei Dong
- Department of Clinical Laboratory, Zhejiang Hospital, Hangzhou, 310013, China
| | - Honghu Chen
- Department of Microbiology, Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, 310051, China
| | - Qingxue Zhou
- Department of Clinical Laboratory, Hangzhou Women's Hospital (Hangzhou Maternity and Child Health Care Hospital), Hangzhou, 310008, China
| | - Ningbo Liao
- College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang, 330045, China.
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Hsieh FC, Chang LK, Tsai CH, Kuan JE, Wu KF, Wu C, Wu WF. Roles of double-loop (130~159 aa and 175~209 aa) in ClpY(HslU)-I domain for SulA substrate degradation by ClpYQ(HslUV) protease in Escherichia coli. J GEN APPL MICROBIOL 2021; 66:297-306. [PMID: 32435002 DOI: 10.2323/jgam.2019.12.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
An Escherichia coli ATP-dependent two-component protease, ClpYQ(HslUV), targets the SulA molecule, an SOS induced protein. ClpY recognizes, unfolds and translocates the substrates into the proteolytic site of ClpQ for degradation. ClpY is divided into three domains N, I and C. The N domain is an ATPase; the C domain allows for oligomerization, while the I domain coordinates substrate binding. In the ClpYQ complex, two layer pore sites, pore I and II, are in the center of its hexameric rings. However, the actual roles of two outer-loop (130~159 aa, L1 and 175~209 aa, L2) of the ClpY-I domain for the degradation of SulA are unclear. In this study, with ATP, the MBP-SulA molecule was bound to ClpY oligomer(s). ClpYΔL1 (ClpY deleted of loop 1) oligomers revealed an excessive SulA-binding activity. With ClpQ, it showed increased proteolytic activity for SulA degradation. Yet, ClpYΔL2 formed fewer oligomers that retained less proteolytic activity, but still had increased SulA-binding activity. In contrast, ClpYΔpore I had a lower SulA-binding activity. ClpYΔ pore I ΔL2 showed the lowest SulA-binding activity. In addition, ClpY (Q198L, Q200L), with a double point mutation in loop 2, formed stable oligomers. It also had a subtle increase in SulA-binding activity, but displayed less proteolytic activity. As a result, loop 2 has an effect on ClpY oligomerization, substrate binding and delivery. Loop 1 has a role as a gate, to prevent excessive substrate binding. Thus, accordingly, ClpY permits the formation of SulA-ClpY(6x), with ATP(s), and this complex then docks through ClpQ(6x) for ultimate proteolytic degradation.
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Affiliation(s)
- Fan-Ching Hsieh
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
| | - Lu-Kao Chang
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
| | - Chih-Hsuan Tsai
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
| | - Jung-En Kuan
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
| | - Ke-Feng Wu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
| | - Cindy Wu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
| | - Whei-Fen Wu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University
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Abstract
Degradation of intracellular proteins in Gram-negative bacteria regulates various cellular processes and serves as a quality control mechanism by eliminating damaged proteins. To understand what causes the proteolytic machinery of the cell to degrade some proteins while sparing others, we employed a quantitative pulsed-SILAC (stable isotope labeling with amino acids in cell culture) method followed by mass spectrometry analysis to determine the half-lives for the proteome of exponentially growing Escherichia coli, under standard conditions. We developed a likelihood-based statistical test to find actively degraded proteins and identified dozens of fast-degrading novel proteins. Finally, we used structural, physicochemical, and protein-protein interaction network descriptors to train a machine learning classifier to discriminate fast-degrading proteins from the rest of the proteome, achieving an area under the receiver operating characteristic curve (AUC) of 0.72.IMPORTANCE Bacteria use protein degradation to control proliferation, dispose of misfolded proteins, and adapt to physiological and environmental shifts, but the factors that dictate which proteins are prone to degradation are mostly unknown. In this study, we have used a combined computational-experimental approach to explore protein degradation in E. coli We discovered that the proteome of E. coli is composed of three protein populations that are distinct in terms of stability and functionality, and we show that fast-degrading proteins can be identified using a combination of various protein properties. Our findings expand the understanding of protein degradation in bacteria and have implications for protein engineering. Moreover, as rapidly degraded proteins may play an important role in pathogenesis, our findings may help to identify new potential antibacterial drug targets.
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7
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Baytshtok V, Fei X, Shih TT, Grant RA, Santos JC, Baker TA, Sauer RT. Heat activates the AAA+ HslUV protease by melting an axial autoinhibitory plug. Cell Rep 2021; 34:108639. [PMID: 33472065 PMCID: PMC7849044 DOI: 10.1016/j.celrep.2020.108639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 11/24/2020] [Accepted: 12/21/2020] [Indexed: 12/03/2022] Open
Abstract
At low temperatures, protein degradation by the AAA+ HslUV protease is very slow. New crystal structures reveal that residues in the intermediate domain of the HslU6 unfoldase can plug its axial channel, blocking productive substrate binding and subsequent unfolding, translocation, and degradation by the HslV12 peptidase. Biochemical experiments with wild-type and mutant enzymes support a model in which heat-induced melting of this autoinhibitory plug activates HslUV proteolysis. Baytshtok et al. demonstrate that the activity of HslUV, a AAA+ heat shock protease, is regulated by thermal melting of its autoinhibitory axial plug, which activates ATP hydrolysis, substrate binding, and energy-dependent proteolysis and ensures that robust protein degradation by HslUV occurs only at elevated temperatures in the cell.
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Affiliation(s)
- Vladimir Baytshtok
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Xue Fei
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tsai-Ting Shih
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert A Grant
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Justin C Santos
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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Li Y, Salazar JK, He Y, Desai P, Porwollik S, Chu W, Paola PSS, Tortorello ML, Juarez O, Feng H, McClelland M, Zhang W. Mechanisms of Salmonella Attachment and Survival on In-Shell Black Peppercorns, Almonds, and Hazelnuts. Front Microbiol 2020; 11:582202. [PMID: 33193218 PMCID: PMC7644838 DOI: 10.3389/fmicb.2020.582202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/27/2020] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica subspecies I (ssp 1) is the leading cause of hospitalizations and deaths due to known bacterial foodborne pathogens in the United States and is frequently implicated in foodborne disease outbreaks associated with spices and nuts. However, the underlying mechanisms of this association have not been fully elucidated. In this study, we evaluated the influence of storage temperature (4 or 25°C), relative humidity (20 or 60%), and food surface characteristics on the attachment and survival of five individual strains representing S. enterica ssp 1 serovars Typhimurium, Montevideo, Braenderup, Mbandaka, and Enteritidis on raw in-shell black peppercorns, almonds, and hazelnuts. We observed a direct correlation between the food surface roughness and S. enterica ssp 1 attachment, and detected significant inter-strain difference in survival on the shell surface under various storage conditions. A combination of low relative humidity (20%) and ambient storage temperature (25°C) resulted in the most significant reduction of S. enterica on shell surfaces (p < 0.05). To identify genes potentially associated with S. enterica attachment and survival on shell surfaces, we inoculated a library of 120,000 random transposon insertion mutants of an S. Enteritidis strain on almond shells, and screened for mutant survival after 1, 3, 7, and 14 days of storage at 20% relative humidity and 25°C. Mutants in 155 S. Enteritidis genes which are involved in carbohydrate metabolic pathways, aerobic and anaerobic respiration, inner membrane transport, and glutamine synthesis displayed significant selection on almond shells (p < 0.05). Findings of this study suggest that various food attributes, environmental factors, and an unexpectedly complex metabolic and regulatory network in S. enterica ssp 1 collectively contribute to the bacterial attachment and survival on low moisture shell surface, providing new data for the future development of knowledge-based intervention strategies.
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Affiliation(s)
- Ye Li
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL, United States
| | - Joelle K Salazar
- Division of Food Processing Science and Technology, U.S. Food and Drug Administration, Bedford Park, IL, United States
| | - Yingshu He
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL, United States
| | - Prerak Desai
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Weiping Chu
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Palma-Salgado Sindy Paola
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Mary Lou Tortorello
- Division of Food Processing Science and Technology, U.S. Food and Drug Administration, Bedford Park, IL, United States
| | - Oscar Juarez
- Department of Biology, Illinois Institute of Technology, Chicago, IL, United States
| | - Hao Feng
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, University of California, Irvine, Irvine, CA, United States
| | - Wei Zhang
- Department of Food Science and Nutrition, Illinois Institute of Technology, Bedford Park, IL, United States
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Ropelewska M, Gross MH, Konieczny I. DNA and Polyphosphate in Directed Proteolysis for DNA Replication Control. Front Microbiol 2020; 11:585717. [PMID: 33123115 PMCID: PMC7566177 DOI: 10.3389/fmicb.2020.585717] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 09/10/2020] [Indexed: 12/03/2022] Open
Abstract
The strict control of bacterial cell proliferation by proteolysis is vital to coordinate cell cycle processes and to adapt to environmental changes. ATP-dependent proteases of the AAA + family are molecular machineries that contribute to cellular proteostasis. Their activity is important to control the level of various proteins, including those that are essential for the regulation of DNA replication. Since the process of proteolysis is irreversible, the protease activity must be tightly regulated and directed toward a specific substrate at the exact time and space in a cell. In our mini review, we discuss the impact of phosphate-containing molecules like DNA and inorganic polyphosphate (PolyP), accumulated during stress, on protease activities. We describe how the directed proteolysis of essential replication proteins contributes to the regulation of DNA replication under normal and stress conditions in bacteria.
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Affiliation(s)
- Malgorzata Ropelewska
- Laboratory of Molecular Biology, Intercollegiate Faculty of Biotechnology of University of Gdańsk and Medical University of Gdańsk, Gdańsk, Poland
| | - Marta H Gross
- Laboratory of Molecular Biology, Intercollegiate Faculty of Biotechnology of University of Gdańsk and Medical University of Gdańsk, Gdańsk, Poland
| | - Igor Konieczny
- Laboratory of Molecular Biology, Intercollegiate Faculty of Biotechnology of University of Gdańsk and Medical University of Gdańsk, Gdańsk, Poland
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Ceyssens PJ, De Smet J, Wagemans J, Akulenko N, Klimuk E, Hedge S, Voet M, Hendrix H, Paeshuyse J, Landuyt B, Xu H, Blanchard J, Severinov K, Lavigne R. The Phage-Encoded N-Acetyltransferase Rac Mediates Inactivation of Pseudomonas aeruginosa Transcription by Cleavage of the RNA Polymerase Alpha Subunit. Viruses 2020; 12:v12090976. [PMID: 32887488 PMCID: PMC7552054 DOI: 10.3390/v12090976] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 08/26/2020] [Accepted: 09/01/2020] [Indexed: 12/20/2022] Open
Abstract
In this study, we describe the biological function of the phage-encoded protein RNA polymerase alpha subunit cleavage protein (Rac), a predicted Gcn5-related acetyltransferase encoded by phiKMV-like viruses. These phages encode a single-subunit RNA polymerase for transcription of their late (structure- and lysis-associated) genes, whereas the bacterial RNA polymerase is used at the earlier stages of infection. Rac mediates the inactivation of bacterial transcription by introducing a specific cleavage in the α subunit of the bacterial RNA polymerase. This cleavage occurs within the flexible linker sequence and disconnects the C-terminal domain, required for transcription initiation from most highly active cellular promoters. To achieve this, Rac likely taps into a novel post-translational modification (PTM) mechanism within the host Pseudomonas aeruginosa. From an evolutionary perspective, this novel phage-encoded regulation mechanism confirms the importance of PTMs in the prokaryotic metabolism and represents a new way by which phages can hijack the bacterial host metabolism.
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Affiliation(s)
- Pieter-Jan Ceyssens
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
| | - Jeroen De Smet
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
| | - Jeroen Wagemans
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
| | - Natalia Akulenko
- Institute of Molecular Genetics, Russian Academy of Sciences, 119334 Moscow, Russia; (N.A.); (E.K.); (K.S.)
| | - Evgeny Klimuk
- Institute of Molecular Genetics, Russian Academy of Sciences, 119334 Moscow, Russia; (N.A.); (E.K.); (K.S.)
| | - Subray Hedge
- Department of Biochemistry, Albert Einstein College of Medicine, New York, NY 10461, USA; (S.H.); (H.X.); (J.B.)
| | - Marleen Voet
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
| | - Hanne Hendrix
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
| | - Jan Paeshuyse
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
| | - Bart Landuyt
- Department of Biology, KU Leuven, 3000 Leuven, Belgium;
| | - Hua Xu
- Department of Biochemistry, Albert Einstein College of Medicine, New York, NY 10461, USA; (S.H.); (H.X.); (J.B.)
| | - John Blanchard
- Department of Biochemistry, Albert Einstein College of Medicine, New York, NY 10461, USA; (S.H.); (H.X.); (J.B.)
| | - Konstantin Severinov
- Institute of Molecular Genetics, Russian Academy of Sciences, 119334 Moscow, Russia; (N.A.); (E.K.); (K.S.)
| | - Rob Lavigne
- Department of Biosystems, KU Leuven, 3000 Leuven, Belgium; (P.-J.C.); (J.D.S.); (J.W.); (M.V.); (H.H.); (J.P.)
- Correspondence: ; Tel.: +32-16-379-524
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11
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Scull NW, Lucius AL. Kinetic Analysis of AAA+ Translocases by Combined Fluorescence and Anisotropy Methods. Biophys J 2020; 119:1335-1350. [PMID: 32997959 DOI: 10.1016/j.bpj.2020.08.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 08/03/2020] [Accepted: 08/17/2020] [Indexed: 11/30/2022] Open
Abstract
The multitude of varied, energy-dependent processes that exist in the cell necessitate a diverse array of macromolecular machines to maintain homeostasis, allow for growth, and facilitate reproduction. ATPases associated with various cellular activity are a set of protein assemblies that function as molecular motors to couple the energy of nucleoside triphosphate binding and hydrolysis to mechanical movement along a polymer lattice. A recent boom in structural insights into these motors has led to structural hypotheses on how these motors fulfill their function. However, in many cases, we lack direct kinetic measurements of the dynamic processes these motors undergo as they transition between observed structural states. Consequently, there is a need for improved techniques for testing the structural hypotheses in solution. Here, we apply transient-state fluorescence anisotropy and total fluorescence stopped-flow methods to the analysis of polypeptide translocation catalyzed by these ATPase motors. We specifically focus on the Hsp100-Clp protein system of ClpA, which is a well-studied, model ATPases associated with various cellular activity system that has both eukaryotic and archaea homologs. Using this system, we show that we can reproduce previously established kinetic parameters from the simultaneous analysis of fluorescence anisotropy and total fluorescence and overcome previous limitations of our previous approach. Specifically, for the first time, to our knowledge, we obtain quantitative interpretations of the translocation of polypeptide substrates longer than 100 aa.
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Affiliation(s)
- Nathaniel W Scull
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama
| | - Aaron L Lucius
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama.
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12
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Crosskey TD, Beckham KS, Wilmanns M. The ATPases of the mycobacterial type VII secretion system: Structural and mechanistic insights into secretion. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 152:25-34. [DOI: 10.1016/j.pbiomolbio.2019.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 11/08/2019] [Accepted: 11/22/2019] [Indexed: 12/12/2022]
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13
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The molecular principles governing the activity and functional diversity of AAA+ proteins. Nat Rev Mol Cell Biol 2019; 21:43-58. [PMID: 31754261 DOI: 10.1038/s41580-019-0183-6] [Citation(s) in RCA: 118] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2019] [Indexed: 12/26/2022]
Abstract
ATPases associated with diverse cellular activities (AAA+ proteins) are macromolecular machines that convert the chemical energy contained in ATP molecules into powerful mechanical forces to remodel a vast array of cellular substrates, including protein aggregates, macromolecular complexes and polymers. AAA+ proteins have key functionalities encompassing unfolding and disassembly of such substrates in different subcellular localizations and, hence, power a plethora of fundamental cellular processes, including protein quality control, cytoskeleton remodelling and membrane dynamics. Over the past 35 years, many of the key elements required for AAA+ activity have been identified through genetic, biochemical and structural analyses. However, how ATP powers substrate remodelling and whether a shared mechanism underlies the functional diversity of the AAA+ superfamily were uncertain. Advances in cryo-electron microscopy have enabled high-resolution structure determination of AAA+ proteins trapped in the act of processing substrates, revealing a conserved core mechanism of action. It has also become apparent that this common mechanistic principle is structurally adjusted to carry out a diverse array of biological functions. Here, we review how substrate-bound structures of AAA+ proteins have expanded our understanding of ATP-driven protein remodelling.
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14
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Puchades C, Rampello AJ, Shin M, Giuliano CJ, Wiseman RL, Glynn SE, Lander GC. Structure of the mitochondrial inner membrane AAA+ protease YME1 gives insight into substrate processing. Science 2018; 358:358/6363/eaao0464. [PMID: 29097521 DOI: 10.1126/science.aao0464] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/25/2017] [Indexed: 12/20/2022]
Abstract
We present an atomic model of a substrate-bound inner mitochondrial membrane AAA+ quality control protease in yeast, YME1. Our ~3.4-angstrom cryo-electron microscopy structure reveals how the adenosine triphosphatases (ATPases) form a closed spiral staircase encircling an unfolded substrate, directing it toward the flat, symmetric protease ring. Three coexisting nucleotide states allosterically induce distinct positioning of tyrosines in the central channel, resulting in substrate engagement and translocation to the negatively charged proteolytic chamber. This tight coordination by a network of conserved residues defines a sequential, around-the-ring adenosine triphosphate hydrolysis cycle that results in stepwise substrate translocation. A hingelike linker accommodates the large-scale nucleotide-driven motions of the ATPase spiral relative to the planar proteolytic base. The translocation mechanism is likely conserved for other AAA+ ATPases.
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Affiliation(s)
- Cristina Puchades
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute HZ 175, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.,Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Anthony J Rampello
- Department of Biochemistry and Cell Biology, Stony Brook University, 450 Life Sciences Building, Stony Brook, NY 11794, USA
| | - Mia Shin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute HZ 175, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.,Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Christopher J Giuliano
- Department of Biochemistry and Cell Biology, Stony Brook University, 450 Life Sciences Building, Stony Brook, NY 11794, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Steven E Glynn
- Department of Biochemistry and Cell Biology, Stony Brook University, 450 Life Sciences Building, Stony Brook, NY 11794, USA.
| | - Gabriel C Lander
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute HZ 175, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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15
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Abstract
The heat shock response is crucial for organisms against heat-damaged proteins and maintaining homeostasis at a high temperature. Heterologous expression of eukaryotic molecular chaperones protects Escherichia coli from heat stress. Here we report that expression of the plant E3 ligase BnTR1 significantly increases the thermotolerance of E. coli. Different from eukaryotic chaperones, BnTR1 expression induces the accumulation of heat shock factor σ32 and heat shock proteins. The active site of BnTR1 in E. coli is the zinc fingers of the RING domain, which interacts with DnaK resulting in stabilizing σ32. Our findings indicate the expression of BnTR1 confers thermoprotective effects on E. coli cells, and it may provide useful clues to engineer thermophilic bacterial strains.
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16
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Baytshtok V, Chen J, Glynn SE, Nager AR, Grant RA, Baker TA, Sauer RT. Covalently linked HslU hexamers support a probabilistic mechanism that links ATP hydrolysis to protein unfolding and translocation. J Biol Chem 2017; 292:5695-5704. [PMID: 28223361 DOI: 10.1074/jbc.m116.768978] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 02/07/2017] [Indexed: 11/06/2022] Open
Abstract
The HslUV proteolytic machine consists of HslV, a double-ring self-compartmentalized peptidase, and one or two AAA+ HslU ring hexamers that hydrolyze ATP to power the unfolding of protein substrates and their translocation into the proteolytic chamber of HslV. Here, we use genetic tethering and disulfide bonding strategies to construct HslU pseudohexamers containing mixtures of ATPase active and inactive subunits at defined positions in the hexameric ring. Genetic tethering impairs HslV binding and degradation, even for pseudohexamers with six active subunits, but disulfide-linked pseudohexamers do not have these defects, indicating that the peptide tether interferes with HslV interactions. Importantly, pseudohexamers containing different patterns of hydrolytically active and inactive subunits retain the ability to unfold protein substrates and/or collaborate with HslV in their degradation, supporting a model in which ATP hydrolysis and linked mechanical function in the HslU ring operate by a probabilistic mechanism.
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Affiliation(s)
| | | | | | | | | | - Tania A Baker
- From the Department of Biology and.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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17
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Baytshtok V, Fei X, Grant RA, Baker TA, Sauer RT. A Structurally Dynamic Region of the HslU Intermediate Domain Controls Protein Degradation and ATP Hydrolysis. Structure 2016; 24:1766-1777. [PMID: 27667691 DOI: 10.1016/j.str.2016.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/02/2016] [Accepted: 08/06/2016] [Indexed: 11/30/2022]
Abstract
The I domain of HslU sits above the AAA+ ring and forms a funnel-like entry to the axial pore, where protein substrates are engaged, unfolded, and translocated into HslV for degradation. The L199Q I-domain substitution, which was originally reported as a loss-of-function mutation, resides in a segment that appears to adopt multiple conformations as electron density is not observed in HslU and HslUV crystal structures. The L199Q sequence change does not alter the structure of the AAA+ ring or its interactions with HslV but increases I-domain susceptibility to limited endoproteolysis. Notably, the L199Q mutation increases the rate of ATP hydrolysis substantially, results in slower degradation of some proteins but faster degradation of other substrates, and markedly changes the preference of HslUV for initiating degradation at the N or C terminus of model substrates. Thus, a structurally dynamic region of the I domain plays a key role in controlling protein degradation by HslUV.
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Affiliation(s)
- Vladimir Baytshtok
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Xue Fei
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert A Grant
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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18
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Fundamental Characteristics of AAA+ Protein Family Structure and Function. ARCHAEA-AN INTERNATIONAL MICROBIOLOGICAL JOURNAL 2016; 2016:9294307. [PMID: 27703410 PMCID: PMC5039278 DOI: 10.1155/2016/9294307] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Accepted: 07/21/2016] [Indexed: 12/22/2022]
Abstract
Many complex cellular events depend on multiprotein complexes known as molecular machines to efficiently couple the energy derived from adenosine triphosphate hydrolysis to the generation of mechanical force. Members of the AAA+ ATPase superfamily (ATPases Associated with various cellular Activities) are critical components of many molecular machines. AAA+ proteins are defined by conserved modules that precisely position the active site elements of two adjacent subunits to catalyze ATP hydrolysis. In many cases, AAA+ proteins form a ring structure that translocates a polymeric substrate through the central channel using specialized loops that project into the central channel. We discuss the major features of AAA+ protein structure and function with an emphasis on pivotal aspects elucidated with archaeal proteins.
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19
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Chang CY, Hu HT, Tsai CH, Wu WF. The degradation of RcsA by ClpYQ(HslUV) protease in Escherichia coli. Microbiol Res 2016; 184:42-50. [PMID: 26856452 DOI: 10.1016/j.micres.2016.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 12/21/2015] [Accepted: 01/09/2016] [Indexed: 01/30/2023]
Abstract
In Escherichia coli, RcsA, a positive activator for transcription of cps (capsular polysaccharide synthesis) genes, is degraded by the Lon protease. In lon mutant, the accumulation of RcsA leads to overexpression of capsular polysaccharide. In a previous study, overproduction of ClpYQ(HslUV) protease represses the expression of cpsB∷lacZ, but there has been no direct observation demonstrating that ClpYQ degrades RcsA. By means of a MBP-RcsA fusion protein, we showed that RcsA activated cpsB∷lacZ expression and could be rapidly degraded by Lon protease in SG22622 (lon(+)). Subsequently, the comparative half-life experiments performed in the bacterial strains SG22623 (lon) and AC3112 (lon clpY clpQ) indicated that the RcsA turnover rate in AC3112 was relatively slow and RcsA was stable at 30°C or 41°C. In addition, ClpY could interact with RscA in an in vitro pull-down assay, and the more rapid degradation of RcsA was observed in the presence of ClpYQ protease at 41°C. Thus, we conclude that RcsA is indeed proteolized by ClpYQ protease.
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Affiliation(s)
- Chun-Yang Chang
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC
| | - Hui-Ting Hu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC
| | - Chih-Hsuan Tsai
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC
| | - Whei-Fen Wu
- Department of Agricultural Chemistry, College of Bio-Resource and Agriculture, National Taiwan University, Taipei, Taiwan, ROC.
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20
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Olivares AO, Baker TA, Sauer RT. Mechanistic insights into bacterial AAA+ proteases and protein-remodelling machines. Nat Rev Microbiol 2015; 14:33-44. [PMID: 26639779 DOI: 10.1038/nrmicro.2015.4] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To maintain protein homeostasis, AAA+ proteolytic machines degrade damaged and unneeded proteins in bacteria, archaea and eukaryotes. This process involves the ATP-dependent unfolding of a target protein and its subsequent translocation into a self-compartmentalized proteolytic chamber. Related AAA+ enzymes also disaggregate and remodel proteins. Recent structural and biochemical studies, in combination with direct visualization of unfolding and translocation in single-molecule experiments, have illuminated the molecular mechanisms behind these processes and suggest how remodelling of macromolecular complexes by AAA+ enzymes could occur without global denaturation. In this Review, we discuss the structural and mechanistic features of AAA+ proteases and remodelling machines, focusing on the bacterial ClpXP and ClpX as paradigms. We also consider the potential of these enzymes as antibacterial targets and outline future challenges for the field.
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Affiliation(s)
- Adrian O Olivares
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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21
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Li T, Lin J, Lucius AL. Examination of polypeptide substrate specificity for Escherichia coli ClpB. Proteins 2014; 83:117-34. [PMID: 25363713 DOI: 10.1002/prot.24710] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 10/06/2014] [Accepted: 10/18/2014] [Indexed: 12/16/2022]
Abstract
Escherichia coli ClpB is a molecular chaperone that belongs to the Clp/Hsp100 family of AAA+ proteins. ClpB is able to form a hexameric ring structure to catalyze protein disaggregation with the assistance of the DnaK chaperone system. Our knowledge of the mechanism of how ClpB recognizes its substrates is still limited. In this study, we have quantitatively investigated ClpB binding to a number of unstructured polypeptides using steady-state anisotropy titrations. To precisely determine the binding affinity for the interaction between ClpB hexamers and polypeptide substrates the titration data were subjected to global non-linear least squares analysis incorporating the dynamic equilibrium of ClpB assembly. Our results show that ClpB hexamers bind tightly to unstructured polypeptides with binding affinities in the range of ∼3-16 nM. ClpB exhibits a modest preference of binding to Peptide B1 with a binding affinity of (1.7 ± 0.2) nM. Interestingly, we found that ClpB binds to an unstructured polypeptide substrate of 40 and 50 amino acids containing the SsrA sequence at the C-terminus with an affinity of (12 ± 3) nM and (4 ± 2) nM, respectively. Whereas, ClpB binds the 11-amino acid SsrA sequence with an affinity of (140 ± 20) nM, which is significantly weaker than other polypeptide substrates that we tested here. We hypothesize that ClpB, like ClpA, requires substrates with a minimum length for optimal binding. Finally, we present evidence showing that multiple ClpB hexamers are involved in binding to polypeptides ≥152 amino acids.
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Affiliation(s)
- Tao Li
- Department of Chemistry, The University of Alabama at Birmingham, Birmingham, Alabama, 35294-1240
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22
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Yung MC, Ma J, Salemi MR, Phinney BS, Bowman GR, Jiao Y. Shotgun proteomic analysis unveils survival and detoxification strategies by Caulobacter crescentus during exposure to uranium, chromium, and cadmium. J Proteome Res 2014; 13:1833-47. [PMID: 24555639 DOI: 10.1021/pr400880s] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ubiquitous bacterium Caulobacter crescentus holds promise to be used in bioremediation applications due to its ability to mineralize U(VI) under aerobic conditions. Here, cell free extracts of C. crescentus grown in the presence of uranyl nitrate [U(VI)], potassium chromate [Cr(VI)], or cadmium sulfate [Cd(II)] were used for label-free proteomic analysis. Proteins involved in two-component signaling and amino acid metabolism were up-regulated in response to all three metals, and proteins involved in aerobic oxidative phosphorylation and chemotaxis were down-regulated under these conditions. Clustering analysis of proteomic enrichment revealed that the three metals also induce distinct patterns of up- or down-regulated expression among different functional classes of proteins. Under U(VI) exposure, a phytase enzyme and an ABC transporter were up-regulated. Heat shock and outer membrane responses were found associated with Cr(VI), while efflux pumps and oxidative stress proteins were up-regulated with Cd(II). Experimental validations were performed on select proteins. We found that a phytase plays a role in U(VI) and Cr(VI) resistance and detoxification and that a Cd(II)-specific transporter confers Cd(II) resistance. Interestingly, analysis of promoter regions in genes associated with differentially expressed proteins suggests that U(VI) exposure affects cell cycle progression.
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Affiliation(s)
- Mimi C Yung
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory , Livermore, California 94550, United States
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23
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Park E, Lee JW, Yoo HM, Ha BH, An JY, Jeon YJ, Seol JH, Eom SH, Chung CH. Structural alteration in the pore motif of the bacterial 20S proteasome homolog HslV leads to uncontrolled protein degradation. J Mol Biol 2013; 425:2940-54. [PMID: 23707406 DOI: 10.1016/j.jmb.2013.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/29/2013] [Accepted: 05/15/2013] [Indexed: 11/27/2022]
Abstract
In all cells, ATP-dependent proteases play central roles in the controlled degradation of short-lived regulatory or misfolded proteins. A hallmark of these enzymes is that proteolytic active sites are sequestered within a compartmentalized space, which is accessible to substrates only when they are fed into the cavity by protein-unfolding ATPases. HslVU is a prototype of such enzymes, consisting of the hexameric HslU ATPase and the dodecameric HslV protease. HslV forms a barrel-shaped proteolytic chamber with two constricted axial pores. Here, we report that structural alterations of HslV's pore motif dramatically affect the proteolytic activities of both HslV and HslVU complexes. Mutations of a conserved pore residue in HslV (Leu88 to Ala, Gly, or Ser) led to a tighter binding between HslV and HslU and a dramatic stimulation of both the proteolytic and ATPase activities. Furthermore, the HslV mutants alone showed a marked increase of basal hydrolytic activities toward small peptides and unstructured proteins. A synthetic peptide of the HslU C-terminal tail further stimulated the proteolytic activities of these mutants, even allowing degradation of certain folded proteins in the absence of HslU. Moreover, expression of the L88A mutant in Escherichia coli inhibited cell growth, suggesting that HslV pore mutations dysregulate the protease through relaxing the pore constriction, which normally prevents essential cellular proteins from random degradation. Consistent with these observations, an X-ray crystal structure shows that the pore loop of L88A-HslV is largely disordered. Collectively, these results suggest that substrate degradation by HslV is controlled by gating of its pores.
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Affiliation(s)
- Eunyong Park
- School of Biological Sciences, Seoul National University, Seoul 151-742, South Korea
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24
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Liang W, Deutscher MP. Transfer-messenger RNA-SmpB protein regulates ribonuclease R turnover by promoting binding of HslUV and Lon proteases. J Biol Chem 2012; 287:33472-9. [PMID: 22879590 DOI: 10.1074/jbc.m112.375287] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RNase R, an important exoribonuclease involved in degradation of structured RNA, is subject to a novel mechanism of regulation. The enzyme is extremely unstable in rapidly growing cells but becomes stabilized under conditions of stress, such as stationary phase or cold shock. RNase R instability results from acetylation which promotes binding of tmRNA-SmpB, two trans-translation factors, to its C-terminal region. Here, we examine how binding of tmRNA-SmpB leads to proteolysis of RNase R. We show that RNase R degradation is due to two proteases, HslUV and Lon. In their absence, RNase R is stable. We also show, using an in vitro system that accurately replicates the in vivo process, that tmRNA-SmpB is not essential, but it stimulates binding of the protease to the N-terminal region of RNase R and that it does so by a direct interaction between the protease and SmpB which stabilizes protease binding. Thus, a sequence of events, initiated by acetylation of a single Lys residue, results in proteolysis of RNase R in exponential phase cells. RNase R in stationary phase or in cold-shocked cells is not acetylated, and thereby remains stable. Such a regulatory mechanism, dependent on protein acetylation, has not been observed previously in bacterial cells.
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Affiliation(s)
- Wenxing Liang
- Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, Florida 33101, USA
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25
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Sundar S, Baker TA, Sauer RT. The I domain of the AAA+ HslUV protease coordinates substrate binding, ATP hydrolysis, and protein degradation. Protein Sci 2012; 21:188-98. [PMID: 22102327 DOI: 10.1002/pro.2001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 11/11/2022]
Abstract
In the AAA+ HslUV protease, substrates are bound and unfolded by a ring hexamer of HslU, before translocation through an axial pore and into the HslV degradation chamber. Here, we show that the N-terminal residues of an Arc substrate initially bind in the HslU axial pore, with key contacts mediated by a pore loop that is highly conserved in all AAA+ unfoldases. Disordered loops from the six intermediate domains of the HslU hexamer project into a funnel-shaped cavity above the pore and are positioned to contact protein substrates. Mutations in these I-domain loops increase K(M) and decrease V(max) for degradation, increase the mobility of bound substrates, and prevent substrate stimulation of ATP hydrolysis. HslU-ΔI has negligible ATPase activity. Thus, the I domain plays an active role in coordinating substrate binding, ATP hydrolysis, and protein degradation by the HslUV proteolytic machine.
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Affiliation(s)
- Shankar Sundar
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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26
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Abstract
AAA+ family proteolytic machines (ClpXP, ClpAP, ClpCP, HslUV, Lon, FtsH, PAN/20S, and the 26S proteasome) perform protein quality control and are used in regulatory circuits in all cells. These machines contain a compartmental protease, with active sites sequestered in an interior chamber, and a hexameric ring of AAA+ ATPases. Substrate proteins are tethered to the ring, either directly or via adaptor proteins. An unstructured region of the substrate is engaged in the axial pore of the AAA+ ring, and cycles of ATP binding/hydrolysis drive conformational changes that create pulses of pulling that denature the substrate and translocate the unfolded polypeptide through the pore and into the degradation chamber. Here, we review our current understanding of the molecular mechanisms of substrate recognition, adaptor function, and ATP-fueled unfolding and translocation. The unfolding activities of these and related AAA+ machines can also be used to disassemble or remodel macromolecular complexes and to resolubilize aggregates.
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Affiliation(s)
- Robert T Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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27
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Stepwise activity of ClpY (HslU) mutants in the processive degradation of Escherichia coli ClpYQ (HslUV) protease substrates. J Bacteriol 2011; 193:5465-76. [PMID: 21803990 DOI: 10.1128/jb.05128-11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, ClpYQ (HslUV) is a two-component ATP-dependent protease composed of ClpY (HslU), an ATPase with unfolding activity, and ClpQ (HslV), a peptidase. In the ClpYQ proteolytic complex, the hexameric rings of ClpY (HslU) are responsible for protein recognition, unfolding, and translocation into the proteolytic inner chamber of the dodecameric ClpQ (HslV). Each of the three domains, N, I, and C, in ClpY has its own distinct activity. The double loops (amino acids [aa] 137 to 150 and 175 to 209) in domain I of ClpY are necessary for initial recognition/tethering of natural substrates such as SulA, a cell division inhibitor protein. The highly conserved sequence GYVG (aa 90 to 93) pore I site, along with the GESSG pore II site (aa 265 to 269), contribute to the central pore of ClpY in domain N. These two central loops of ClpY are in the center of its hexameric ring in which the energy of ATP hydrolysis allows substrate translocation and then degradation by ClpQ. However, no data have been obtained to determine the effect of the central loops on substrate binding or as part of the processivity of the ClpYQ complex. Thus, we probed the features of ClpY important for substrate engagement and protease processivity via random PCR or site-specific mutagenesis. In yeast two-hybrid analysis and pulldown assays, using isolated ClpY mutants and the pore I or pore II site of ClpY, each was examined for its influence on the adjoining structural regions of the substrates. The pore I site is essential for the translocation of the engaged substrates. Our in vivo study of the ClpY mutants also revealed that an ATP-binding site in domain N, separate from its role in polypeptide (ClpY) oligomerization, is required for complex formation with ClpQ. Additionally, we found that the tyrosine residue at position 408 in ClpY is critical for stabilization of hexamer formation between subunits. Therefore, our studies suggest that stepwise activities of the ClpYQ protease are necessary to facilitate the processive degradation of its natural substrates.
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28
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Meyer AS, Baker TA. Proteolysis in the Escherichia coli heat shock response: a player at many levels. Curr Opin Microbiol 2011; 14:194-9. [PMID: 21353626 DOI: 10.1016/j.mib.2011.02.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 02/03/2011] [Indexed: 11/29/2022]
Abstract
Proteolysis is a fundamental process used by all forms of life to maintain homeostasis, as well as to remodel the proteome following environmental changes. Here, we explore recent advances in understanding the role of proteolysis during the heat shock response of Escherichia coli. Proteolysis both regulates and contributes directly to and the heat shock response at multiple different levels, from adjusting the levels of the master heat shock response regulator (σ(32)), to eliminating damaged cellular proteins, to altering the activity of chaperones that refold heat-denatured proteins. Recent results illustrate the complexity of the heat shock response and the pervasive role that proteolysis plays in both the cellular response to heat shock and the subsequent limiting of the response, as cells return to a more 'normal' physiological state.
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Affiliation(s)
- Anne S Meyer
- Department of Biology, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Sundar S, McGinness KE, Baker TA, Sauer RT. Multiple sequence signals direct recognition and degradation of protein substrates by the AAA+ protease HslUV. J Mol Biol 2010; 403:420-9. [PMID: 20837023 DOI: 10.1016/j.jmb.2010.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/02/2010] [Accepted: 09/03/2010] [Indexed: 11/25/2022]
Abstract
Proteolysis is important for protein quality control and for the proper regulation of many intracellular processes in prokaryotes and eukaryotes. Discerning substrates from other cellular proteins is a key aspect of proteolytic function. The Escherichia coli HslUV protease is a member of a major family of ATP-dependent AAA+ degradation machines. HslU hexamers recognize and unfold native protein substrates and then translocate the polypeptide into the degradation chamber of the HslV peptidase. Although a wealth of structural information is available for this system, relatively little is known about mechanisms of substrate recognition. Here, we demonstrate that mutations in the unstructured N-terminal and C-terminal sequences of two model substrates alter HslUV recognition and degradation kinetics, including changes in V(max). By introducing N- or C-terminal sequences that serve as recognition sites for specific peptide-binding proteins, we show that blocking either terminus of the substrate interferes with HslUV degradation, with synergistic effects when both termini are obstructed. These results support a model in which one terminus of the substrate is tethered to the protease and the other terminus is engaged by the translocation/unfolding machinery in the HslU pore. Thus, degradation appears to consist of discrete steps, which involve the interaction of different terminal sequence signals in the substrate with different receptor sites in the HslUV protease.
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Affiliation(s)
- Shankar Sundar
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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30
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Ayuso-Tejedor S, Nishikori S, Okuno T, Ogura T, Sancho J. FtsH cleavage of non-native conformations of proteins. J Struct Biol 2010; 171:117-24. [DOI: 10.1016/j.jsb.2010.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 05/01/2010] [Accepted: 05/03/2010] [Indexed: 11/17/2022]
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31
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Paddling mechanism for the substrate translocation by AAA+ motor revealed by multiscale molecular simulations. Proc Natl Acad Sci U S A 2009; 106:18237-42. [PMID: 19828442 DOI: 10.1073/pnas.0904756106] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Hexameric ring-shaped AAA+ molecular motors have a key function of active translocation of a macromolecular chain through the central pore. By performing multiscale molecular dynamics (MD) simulations, we revealed that HslU, a AAA+ motor in a bacterial homologue of eukaryotic proteasome, translocates its substrate polypeptide via paddling mechanism during ATP-driven cyclic conformational changes. First, fully atomistic MD simulations showed that the HslU pore grips the threaded signal peptide by the highly conserved Tyr-91 and Val-92 firmly in the closed form and loosely in the open form of the HslU. The grip depended on the substrate sequence. These features were fed into a coarse-grained MD, and conformational transitions of HslU upon ATP cycles were simulated. The simulations exhibited stochastic unidirectional translocation of a polypeptide. This unidirectional translocation is attributed to paddling motions of Tyr-91s between the open and the closed forms: downward motions of Tyr-91s with gripping the substrate and upward motions with slipping on it. The paddling motions were caused by the difference between the characteristic time scales of the pore-radius change and the up-down displacements of Tyr-91s. Computational experiments on mutations at the pore and the substrate were in accord with several experiments.
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32
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Lee JW, Park E, Jeong MS, Jeon YJ, Eom SH, Seol JH, Chung CH. HslVU ATP-dependent protease utilizes maximally six among twelve threonine active sites during proteolysis. J Biol Chem 2009; 284:33475-84. [PMID: 19801685 DOI: 10.1074/jbc.m109.045807] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HslVU is a bacterial ATP-dependent protease distantly related to eukaryotic proteasomes consisting of hexameric HslU ATPase and dodecameric HslV protease. As a homolog of the 20 S proteasome beta-subunits, HslV also uses the N-terminal threonine as the active site residue. However, unlike the proteasome that has only 6 active sites among the 14 beta-subunits, HslV has 12 active sites that could potentially contribute to proteolytic activity. Here, by using a series of HslV dodecamers containing different numbers of active sites, we demonstrate that like the proteasome, HslV with only approximately 6 active sites is sufficient to support full catalytic activity. However, a further reduction of the number of active sites leads to a proportional decrease in activity. Using proteasome inhibitors, we also demonstrate that substrate-mediated stabilization of the HslV-HslU interaction remains unchanged until the number of the active sites is decreased to approximately 6 but is gradually compromised upon further reduction. These results with a mathematical model suggest HslVU utilizes no more than 6 active sites at any given time, presumably because of the action of HslU. These results also suggest that each ATP-bound HslU subunit activates one HslV subunit and that substrate bound to the HslV active site stimulates the HslU ATPase activity by stabilizing the HslV-HslU interaction. We propose this mechanism plays an important role in supporting complete degradation of substrates while preventing wasteful ATP hydrolysis in the resting state by controlling the interaction between HslV and HslU through the catalytic engagement of the proteolytic active sites.
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Affiliation(s)
- Jung Wook Lee
- School of Biological Sciences, Seoul National University, Seoul 151-742, Korea
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33
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Characterization of the Escherichia coli ClpY (HslU) substrate recognition site in the ClpYQ (HslUV) protease using the yeast two-hybrid system. J Bacteriol 2009; 191:4218-31. [PMID: 19395483 DOI: 10.1128/jb.00089-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, ClpYQ (HslUV) is a two-component ATP-dependent protease in which ClpQ is the peptidase subunit and ClpY is the ATPase and the substrate-binding subunit. The ATP-dependent proteolysis is mediated by substrate recognition in the ClpYQ complex. ClpY has three domains, N, I, and C, and these domains are discrete and exhibit different binding preferences. In vivo, ClpYQ targets SulA, RcsA, RpoH, and TraJ molecules. In this study, ClpY was analyzed to identify the molecular determinants required for the binding of its natural protein substrates. Using yeast two-hybrid analysis, we showed that domain I of ClpY contains the residues responsible for recognition of its natural substrates, while domain C is necessary to engage ClpQ. Moreover, the specific residues that lie in the amino acid (aa) 137 to 150 (loop 1) and aa 175 to 209 (loop 2) double loops in domain I of ClpY were shown to be necessary for natural substrate interaction. Additionally, the two-hybrid system, together with random PCR mutagenesis, allowed the isolation of ClpY mutants that displayed a range of binding activities with SulA, including a mutant with no SulA binding trait. Subsequently, via methyl methanesulfonate tests and cpsB::lacZ assays with, e.g., SulA and RcsA as targets, we concluded that aa 175 to 209 of loop 2 are involved in the tethering of natural substrates, and it is likely that both loops, aa 137 to 150 and aa 175 to 209, of ClpY domain I may assist in the delivery of substrates into the inner core for ultimate degradation by ClpQ.
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Koodathingal P, Jaffe NE, Kraut DA, Prakash S, Fishbain S, Herman C, Matouschek A. ATP-dependent proteases differ substantially in their ability to unfold globular proteins. J Biol Chem 2009; 284:18674-84. [PMID: 19383601 DOI: 10.1074/jbc.m900783200] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ATP-dependent proteases control the concentrations of hundreds of regulatory proteins and remove damaged or misfolded proteins from cells. They select their substrates primarily by recognizing sequence motifs or covalent modifications. Once a substrate is bound to the protease, it has to be unfolded and translocated into the proteolytic chamber to be degraded. Some proteases appear to be promiscuous, degrading substrates with poorly defined targeting signals, which suggests that selectivity may be controlled at additional levels. Here we compare the abilities of representatives from all classes of ATP-dependent proteases to unfold a model substrate protein and find that the unfolding abilities range over more than 2 orders of magnitude. We propose that these differences in unfolding abilities contribute to the fates of substrate proteins and may act as a further layer of selectivity during protein destruction.
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Affiliation(s)
- Prakash Koodathingal
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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35
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Evolution of the ssrA degradation tag in Mycoplasma: specificity switch to a different protease. Proc Natl Acad Sci U S A 2008; 105:16113-8. [PMID: 18852454 DOI: 10.1073/pnas.0808802105] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Stalled ribosomes in bacteria are rescued by the tmRNA system. In this process, the nascent polypeptide is modified by the addition of a short C-terminal sequence called the ssrA tag, which is encoded by tmRNA and allows normal termination and release of ribosomal subunits. In most bacteria, ssrA-tagged proteins are degraded by the AAA+ protease, ClpXP. However, in bacterial species of the genus Mycoplasma, genes for ClpXP and many other proteins were lost through reductive evolution. Interestingly, Mycoplasma ssrA tag sequences are very different from the tags in other bacteria. We report that ssrA-tagged proteins in Mesoplasma florum, a Mycoplasma species, are efficiently recognized and degraded by the AAA+ Lon protease. Thus, retaining degradation of ssrA-tagged translation products was apparently important enough during speciation of Mycoplasma to drive adaptation of the ssrA tag to a different protease. These results emphasize the importance of coupling proteolysis with tmRNA-mediated tagging and ribosome rescue.
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36
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Karradt A, Sobanski J, Mattow J, Lockau W, Baier K. NblA, a key protein of phycobilisome degradation, interacts with ClpC, a HSP100 chaperone partner of a cyanobacterial Clp protease. J Biol Chem 2008; 283:32394-403. [PMID: 18818204 DOI: 10.1074/jbc.m805823200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
When cyanobacteria are starved for nitrogen, expression of the NblA protein increases and thereby induces proteolytic degradation of phycobilisomes, light-harvesting complexes of pigmented proteins. Phycobilisome degradation leads to a color change of the cells from blue-green to yellow-green, referred to as bleaching or chlorosis. As reported previously, NblA binds via a conserved region at its C terminus to the alpha-subunits of phycobiliproteins, the main components of phycobilisomes. We demonstrate here that a highly conserved stretch of amino acids in the N-terminal helix of NblA is essential for protein function in vivo. Affinity purification of glutathione S-transferase-tagged NblA, expressed in a Nostoc sp. PCC7120 mutant lacking wild-type NblA, resulted in co-precipitation of ClpC, encoded by open reading frame alr2999 of the Nostoc chromosome. ClpC is a HSP100 chaperone partner of the Clp protease. ATP-dependent binding of NblA to ClpC was corroborated by in vitro pull-down assays. Introducing amino acid exchanges, we verified that the conserved N-terminal motif of NblA mediates the interaction with ClpC. Further results indicate that NblA binds phycobiliprotein subunits and ClpC simultaneously, thus bringing the proteins into close proximity. Altogether these results suggest that NblA may act as an adaptor protein that guides a ClpC.ClpP complex to the phycobiliprotein disks in the rods of phycobilisomes, thereby initiating the degradation process.
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Affiliation(s)
- Anne Karradt
- Institut für Biologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, D-10115 Berlin
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37
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Abstract
Proteins unfold constantly in cells, especially under stress conditions. Degradation of denatured polypeptides by Lon and related ATP-dependent AAA(+) proteases helps prevent toxic aggregates formation and other deleterious consequences, but how these destructive enzymatic machines distinguish between damaged and properly folded proteins is poorly understood. Here, we show that Escherichia coli Lon recognizes specific sequences -- rich in aromatic residues -- that are accessible in unfolded polypeptides but hidden in most native structures. Denatured polypeptides lacking such sequences are poor substrates. Lon also unfolds and degrades stably folded proteins with accessible recognition tags. Thus, protein architecture and the positioning of appropriate targeting sequences allow Lon degradation to be dependent or independent of the folding status of a protein. Our results suggest that Lon can recognize multiple signals in unfolded polypeptides synergistically, resulting in nanomolar binding and a mechanism for discriminating irreversibly damaged proteins from transiently unfolded elements of structure.
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Affiliation(s)
- Eyal Gur
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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38
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Yakamavich JA, Baker TA, Sauer RT. Asymmetric nucleotide transactions of the HslUV protease. J Mol Biol 2008; 380:946-57. [PMID: 18582897 DOI: 10.1016/j.jmb.2008.05.070] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 05/27/2008] [Accepted: 05/29/2008] [Indexed: 10/22/2022]
Abstract
ATP binding and hydrolysis are critical for protein degradation by HslUV, a AAA(+) machine containing one or two HslU(6) ATPases and the HslV(12) peptidase. Although each HslU homohexamer has six potential ATP-binding sites, we show that only three or four ATP molecules bind at saturation and present evidence for three functional subunit classes. These results imply that only a subset of HslU and HslUV crystal structures represents functional enzyme conformations. Our results support an asymmetric mechanism of ATP binding and hydrolysis, and suggest that molecular contacts between HslU and HslV vary dynamically throughout the ATPase cycle. Nucleotide binding controls HslUV assembly and activity. Binding of a single ATP allows HslU to bind HslV, whereas additional ATPs must bind HslU to support substrate recognition and to activate ATP hydrolysis, which powers substrate unfolding and translocation. Thus, a simple thermodynamic hierarchy ensures that substrates bind to functional HslUV complexes, that ATP hydrolysis is efficiently coupled to protein degradation, and that working HslUV does not dissociate, allowing highly processive degradation.
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Affiliation(s)
- Joseph A Yakamavich
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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39
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Valas RE, Bourne PE. Rethinking proteasome evolution: two novel bacterial proteasomes. J Mol Evol 2008; 66:494-504. [PMID: 18389302 PMCID: PMC3235984 DOI: 10.1007/s00239-008-9075-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 01/23/2008] [Accepted: 01/25/2008] [Indexed: 12/22/2022]
Abstract
The proteasome is a multisubunit structure that degrades proteins. Protein degradation is an essential component of regulation because proteins can become misfolded, damaged, or unnecessary. Proteasomes and their homologues vary greatly in complexity: from HslV (heat shock locus v), which is encoded by 1 gene in bacteria, to the eukaryotic 20S proteasome, which is encoded by more than 14 genes. Despite this variation in complexity, all the proteasomes are composed of homologous subunits. We searched 238 complete bacterial genomes for structures related to the proteasome and found evidence of two novel groups of bacterial proteasomes. The first, which we name Anbu, is sparsely distributed among cyanobacteria and proteobacteria. We hypothesize that Anbu must be very ancient because of its distribution within the cyanobacteria, and that it has been lost in many more recent species. We also present evidence for a fourth type of bacterial proteasome found in a few beta-proteobacteria, which we call beta-proteobacteria proteasome homologue (BPH). Sequence and structural analyses show that Anbu and BPH are both distinct from known bacterial proteasomes but have homologous structures. Anbu is encoded by one gene, so we postulate a duplication of Anbu created the 20S proteasome. Anbu's function appears to be related to transglutaminase activity, not the general stress response associated with HslV. We have found different combinations of Anbu, BPH, and HslV within these bacterial genomes, which raises questions about specialized protein degradation systems.
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Affiliation(s)
- Ruben E. Valas
- Bioinformatics Program, University of California, San Diego, 9500 Gilman Drive, MC 0743, La Jolla, CA 92093 USA
| | - Philip E. Bourne
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093 USA
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40
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Lee S, Choi JM, Tsai FTF. Visualizing the ATPase cycle in a protein disaggregating machine: structural basis for substrate binding by ClpB. Mol Cell 2007; 25:261-71. [PMID: 17244533 PMCID: PMC1855157 DOI: 10.1016/j.molcel.2007.01.002] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 10/10/2006] [Accepted: 01/03/2007] [Indexed: 11/17/2022]
Abstract
ClpB is a ring-shaped molecular chaperone that has the remarkable ability to disaggregate stress-damaged proteins. Here we present the electron cryomicroscopy reconstruction of an ATP-activated ClpB trap mutant, along with reconstructions of ClpB in the AMPPNP, ADP, and in the nucleotide-free state. We show that motif 2 of the ClpB M domain is positioned between the D1-large domains of neighboring subunits and could facilitate a concerted, ATP-driven conformational change in the AAA-1 ring. We further demonstrate biochemically that ATP is essential for high-affinity substrate binding to ClpB and cannot be substituted with AMPPNP. Our structures show that in the ATP-activated state, the D1 loops are stabilized at the central pore, providing the structural basis for high-affinity substrate binding. Taken together, our results support a mechanism by which ClpB captures substrates on the upper surface of the AAA-1 ring before threading them through the ClpB hexamer in an ATP hydrolysis-driven step.
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Affiliation(s)
- Sukyeong Lee
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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41
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Haslberger T, Weibezahn J, Zahn R, Lee S, Tsai FTF, Bukau B, Mogk A. M domains couple the ClpB threading motor with the DnaK chaperone activity. Mol Cell 2007; 25:247-60. [PMID: 17244532 DOI: 10.1016/j.molcel.2006.11.008] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 10/10/2006] [Accepted: 11/08/2006] [Indexed: 11/17/2022]
Abstract
The AAA(+) chaperone ClpB mediates the reactivation of aggregated proteins in cooperation with the DnaK chaperone system. ClpB consists of two AAA domains that drive the ATP-dependent threading of substrates through a central translocation channel. Its unique middle (M) domain forms a coiled-coil structure that laterally protrudes from the ClpB ring and is essential for aggregate solubilization. Here, we demonstrate that the conserved helix 3 of the M domain is specifically required for the DnaK-dependent shuffling of aggregated proteins, but not of soluble denatured substrates, to the pore entrance of the ClpB translocation channel. Helix 3 exhibits nucleotide-driven conformational changes possibly involving a transition between folded and unfolded states. This molecular switch controls the ClpB ATPase cycle by contacting the first ATPase domain and establishes the M domain as a regulatory device that acts in the disaggregation process by coupling the threading motor of ClpB with the DnaK chaperone activity.
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Affiliation(s)
- Tobias Haslberger
- ZMBH, Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
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42
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Farrell CM, Baker TA, Sauer RT. Altered specificity of a AAA+ protease. Mol Cell 2007; 25:161-6. [PMID: 17218279 PMCID: PMC1847774 DOI: 10.1016/j.molcel.2006.11.018] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 11/15/2006] [Accepted: 11/20/2006] [Indexed: 10/23/2022]
Abstract
ClpXP, an ATP-dependent protease, degrades hundreds of different intracellular proteins. ClpX chooses substrates by binding peptide tags, typically displayed at the N or C terminus of the protein to be degraded. Here, we identify a ClpX mutant that displays a 300-fold change in substrate specificity, resulting in decreased degradation of ssrA-tagged substrates but improved degradation of proteins with other classes of degradation signals. The altered-specificity mutation occurs within "RKH" loops, which surround the entrance to the central pore of the ClpX hexamer and are highly conserved in the ClpX subfamily of AAA+ ATPases. These results support a major role for the RKH loops in substrate recognition and suggest that ClpX specificity represents an evolutionary compromise that has optimized degradation of multiple types of substrates rather than any single class.
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Affiliation(s)
| | - Tania A. Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, 02139
| | - Robert T. Sauer
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139
- *Correspondence:
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43
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Chaba R, Grigorova IL, Flynn JM, Baker TA, Gross CA. Design principles of the proteolytic cascade governing the sigmaE-mediated envelope stress response in Escherichia coli: keys to graded, buffered, and rapid signal transduction. Genes Dev 2007; 21:124-36. [PMID: 17210793 PMCID: PMC1759897 DOI: 10.1101/gad.1496707] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Proteolytic cascades often transduce signals between cellular compartments, but the features of these cascades that permit efficient conversion of a biological signal into a transcriptional output are not well elucidated. sigma(E) mediates an envelope stress response in Escherichia coli, and its activity is controlled by regulated degradation of RseA, a membrane-spanning anti-sigma factor. Examination of the individual steps in this protease cascade reveals that the initial, signal-sensing cleavage step is rate-limiting; that multiple ATP-dependent proteases degrade the cytoplasmic fragment of RseA and that dissociation of sigma(E) from RseA is so slow that most free sigma(E) must be generated by the active degradation of RseA. As a consequence, the degradation rate of RseA is set by the amount of inducing signal, and insulated from the "load" on and activity of the cytoplasmic proteases. Additionally, changes in RseA degradation rate are rapidly reflected in altered sigma(E) activity. These design features are attractive as general components of signal transduction pathways governed by unstable negative regulators.
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Affiliation(s)
- Rachna Chaba
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA
| | - Irina L. Grigorova
- Graduate Group in Biophysics, University of California at San Francisco, San Francisco, California 94158, USA
| | - Julia M. Flynn
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Tania A. Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Carol A. Gross
- Department of Microbiology and Immunology, University of California at San Francisco, San Francisco, California 94158, USA
- Department of Cell and Tissue Biology, University of California at San Francisco, San Francisco, California 94158, USA
- Corresponding author.E-MAIL ; FAX (415) 514-4080
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44
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Graef M, Seewald G, Langer T. Substrate recognition by AAA+ ATPases: distinct substrate binding modes in ATP-dependent protease Yme1 of the mitochondrial intermembrane space. Mol Cell Biol 2007; 27:2476-85. [PMID: 17261594 PMCID: PMC1899909 DOI: 10.1128/mcb.01721-06] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The energy-dependent proteolysis of cellular proteins is mediated by conserved proteolytic AAA(+) complexes. Two such machines, the m- and i-AAA proteases, are present in the mitochondrial inner membrane. They exert chaperone-like properties and specifically degrade nonnative membrane proteins. However, molecular mechanisms of substrate engagement by AAA proteases remained elusive. Here, we define initial steps of substrate recognition and identify two distinct substrate binding sites in the i-AAA protease subunit Yme1. Misfolded polypeptides are recognized by conserved helices in proteolytic and AAA domains. Structural modeling reveals a lattice-like arrangement of these helices at the surface of hexameric AAA protease ring complexes. While helices within the AAA domain apparently play a general role for substrate binding, the requirement for binding to surface-exposed helices within the proteolytic domain is determined by the folding and membrane association of substrates. Moreover, an assembly factor of cytochrome c oxidase, Cox20, serves as a substrate-specific cofactor during proteolysis and modulates the initial interaction of nonassembled Cox2 with the protease. Our findings therefore reveal the existence of alternative substrate recognition pathways within AAA proteases and shed new light on molecular mechanisms ensuring the specificity of proteolysis by energy-dependent proteases.
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Affiliation(s)
- Martin Graef
- Institut für Genetik, Universität zu Köln, Zülpicher Strasse 47, 50674 Köln, Germany
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45
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Baker TA, Sauer RT. ATP-dependent proteases of bacteria: recognition logic and operating principles. Trends Biochem Sci 2006; 31:647-53. [PMID: 17074491 PMCID: PMC2717004 DOI: 10.1016/j.tibs.2006.10.006] [Citation(s) in RCA: 216] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 09/22/2006] [Accepted: 10/20/2006] [Indexed: 11/29/2022]
Abstract
ATP-powered AAA+ proteases degrade specific proteins in intracellular environments occupied by thousands of different proteins. These proteases operate as powerful molecular machines that unfold stable native proteins before degradation. Understanding how these enzymes choose the "right" protein substrates at the "right" time is key to understanding their biological function. Recently, proteomic approaches have identified numerous substrates for some bacterial enzymes and the sequence motifs responsible for recognition. Advances have also been made in elucidating the mechanism and impact of adaptor proteins in regulating substrate choice. Finally, recent biochemical dissection of the ATPase cycle and its coupling to protein unfolding has revealed fundamental operating principles of this important, ubiquitous family of molecular machines.
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Affiliation(s)
- Tania A Baker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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46
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Suno R, Niwa H, Tsuchiya D, Zhang X, Yoshida M, Morikawa K. Structure of the whole cytosolic region of ATP-dependent protease FtsH. Mol Cell 2006; 22:575-85. [PMID: 16762831 DOI: 10.1016/j.molcel.2006.04.020] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2006] [Revised: 02/17/2006] [Accepted: 04/18/2006] [Indexed: 11/25/2022]
Abstract
An ATP-dependent protease, FtsH, digests misassembled membrane proteins in order to maintain membrane integrity and digests short-lived soluble proteins in order to control their cellular regulation. This enzyme has an N-terminal transmembrane segment and a C-terminal cytosolic region consisting of an AAA+ ATPase domain and a protease domain. Here we present two crystal structures: the protease domain and the whole cytosolic region. The cytosolic region fully retains an ATP-dependent protease activity and adopts a three-fold-symmetric hexameric structure. The protease domains displayed a six-fold symmetry, while the AAA+ domains, each containing ADP, alternate two orientations relative to the protease domain, making "open" and "closed" interdomain contacts. Apparently, ATPase is active only in the closed form, and protease operates in the open form. The protease catalytic sites are accessible only through a tunnel following from the AAA+ domain of the adjacent subunit, raising a possibility of translocation of polypeptide substrate to the protease sites through this tunnel.
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Affiliation(s)
- Ryoji Suno
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503, Japan
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Hoyt MA, Zich J, Takeuchi J, Zhang M, Govaerts C, Coffino P. Glycine-alanine repeats impair proper substrate unfolding by the proteasome. EMBO J 2006; 25:1720-9. [PMID: 16601692 PMCID: PMC1440830 DOI: 10.1038/sj.emboj.7601058] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 03/01/2006] [Indexed: 11/09/2022] Open
Abstract
Proteasome ATPases unravel folded proteins. Introducing a sequence containing only glycine and alanine residues (GAr) into substrates can impair their digestion. We previously proposed that a GAr interferes with the unfolding capacity of the proteasome, leading to partial degradation of products. Here we tested that idea in several ways. Stabilizing or destabilizing a folded domain within substrate proteins changed GAr-mediated intermediate production in the way predicted by the model. A downstream folded domain determined the sites of terminal proteolysis. The spacing between a GAr and a folded domain was critical for intermediate production. Intermediates containing a GAr did not remain associated with proteasomes, excluding models whereby retained GAr-containing proteins halt further processing. The following model is supported: a GAr positioned within the ATPase ring reduces the efficiency of coupling between nucleotide hydrolysis and work performed on the substrate. If this impairment takes place when unfolding must be initiated, insertion pauses and proteolysis is limited to the portion of the substrate that has already entered the catalytic chamber of the proteasome.
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Affiliation(s)
- Martin A Hoyt
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
| | - Judith Zich
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
| | - Junko Takeuchi
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
| | - Mingsheng Zhang
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
| | - Cedric Govaerts
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, CA, USA
| | - Philip Coffino
- Department of Microbiology and Immunology, University of California, San Francisco, CA, USA
- Department of Microbiology and Immunology, UCSF, 513 Parnassus Avenue, San Francisco, CA 94143-0414, USA. Tel.: +1 415 476 1783; E-mail:
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Bösl B, Grimminger V, Walter S. The molecular chaperone Hsp104--a molecular machine for protein disaggregation. J Struct Biol 2006; 156:139-48. [PMID: 16563798 DOI: 10.1016/j.jsb.2006.02.004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 02/06/2006] [Accepted: 02/09/2006] [Indexed: 11/25/2022]
Abstract
At the Cold Spring Harbor Meeting on 'Molecular Chaperones and the Heat Shock Response' in May 1996, Susan Lindquist presented evidence that a chaperone of yeast termed Hsp104, which her group had been investigating for several years, is able to dissolve protein aggregates (Glover, J.R., Lindquist, S., 1998. Hsp104, Hsp70, and Hsp40: a novel chaperone system that rescues previously aggregated proteins. Cell 94, 73-82). Among many of the participants this news stimulated reactions reaching from decided skepticism to utter disbelief because protein aggregation was widely considered to be an irreversible process. Several years and publications later, it is undeniable that Susan had been right. Hsp104 is an ATP dependent molecular machine that-in cooperation with Hsp70 and Hsp40-extracts polypeptide chains from protein aggregates and facilitates their refolding, although the molecular details of this process are still poorly understood. Meanwhile, close homologues of Hsp104 have been identified in bacteria (ClpB), in mitochondria (Hsp78), and in the cytosol of plants (Hsp101), but intriguingly not in the cytosol of animal cells (Mosser, D.D., Ho, S., Glover, J.R., 2004. Saccharomyces cerevisiae Hsp104 enhances the chaperone capacity of human cells and inhibits heat stress-induced proapoptotic signaling. Biochemistry 43, 8107-8115). Observations that Hsp104 plays an essential role in the maintenance of yeast prions (see review by James Shorter in this issue) have attracted even more attention to the molecular mechanism of this ATP dependent chaperone (Chernoff, Y.O., Lindquist, S.L., Ono, B., Inge-Vechtomov, S.G., Liebman, S.W., 1995. Role of the chaperone protein Hsp104 in propagation of the yeast prion-like factor [PSI+]. Science 268, 880-884).
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Affiliation(s)
- Benjamin Bösl
- Department für Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany
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Graef M, Langer T. Substrate specific consequences of central pore mutations in the i-AAA protease Yme1 on substrate engagement. J Struct Biol 2006; 156:101-8. [PMID: 16527490 DOI: 10.1016/j.jsb.2006.01.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Revised: 01/13/2006] [Accepted: 01/13/2006] [Indexed: 11/26/2022]
Abstract
Two membrane-bound ATP-dependent AAA proteases conduct protein quality surveillance in the inner membrane of mitochondria and control crucial steps during mitochondrial biogenesis. AAA domains of proteolytic subunits are critical for the recognition of non-native membrane proteins which are extracted from the membrane bilayer for proteolysis. Here, we have analysed the role of the conserved loop motif YVG, which has been localized to the central pore in other hexameric AAA(+) ring complexes, for the degradation of membrane proteins by the i-AAA protease Yme1. Proteolytic activity was found to depend on the presence of hydrophobic amino acid residues at position 354 within the pore loop of Yme1. Mutations affected proteolysis in a substrate-specific manner: whereas the degradation of misfolded membrane proteins was impaired at a post-binding step, folded substrate proteins did not interact with mutant Yme1. This reflects most likely deficiencies in the ATP-dependent unfolding of substrate proteins, since we observed similar effects for ATPase-deficient Yme1 mutants. Our findings therefore suggest an essential function of the central pore loop for the ATP-dependent translocation of membrane proteins into a proteolytic cavity formed by AAA proteases.
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Affiliation(s)
- Martin Graef
- Institute for Genetics and Center for Molecular Medicine, CMMC, University of Cologne, Cologne, Germany
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Nishii W, Suzuki T, Nakada M, Kim YT, Muramatsu T, Takahashi K. Cleavage mechanism of ATP-dependent Lon protease toward ribosomal S2 protein. FEBS Lett 2005; 579:6846-50. [PMID: 16337203 DOI: 10.1016/j.febslet.2005.11.026] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 10/13/2005] [Accepted: 11/03/2005] [Indexed: 12/01/2022]
Abstract
The Escherichia coli ATP-dependent protease Lon degrades ribosomal S2 protein in the presence of inorganic polyphosphate (polyP). In this study, the process of the degradation was investigated in detail. During the degradation, 68 peptides with various sizes (4-29 residues) were produced in a processive fashion. Cleavage occurred at 45 sites, whose P1 and P3 positions were dominantly occupied by hydrophobic residues. These cleavage sites were located preferentially at the regions with rigid secondary structures and the P1 residues of the major cleavage sites appeared to be concealed from the surface of the substrate molecule. Furthermore, polyP changed not only the substrate preference but also the oligomeric structure of the enzyme.
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Affiliation(s)
- Wataru Nishii
- School of Life Science, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
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