1
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Mindrebo JT, Lander GC. Structural and mechanistic studies on human LONP1 redefine the hand-over-hand translocation mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.24.600538. [PMID: 38979310 PMCID: PMC11230189 DOI: 10.1101/2024.06.24.600538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
AAA+ enzymes use energy from ATP hydrolysis to remodel diverse cellular targets. Structures of substrate-bound AAA+ complexes suggest that these enzymes employ a conserved hand-over-hand mechanism to thread substrates through their central pore. However, the fundamental aspects of the mechanisms governing motor function and substrate processing within specific AAA+ families remain unresolved. We used cryo-electron microscopy to structurally interrogate reaction intermediates from in vitro biochemical assays to inform the underlying regulatory mechanisms of the human mitochondrial AAA+ protease, LONP1. Our results demonstrate that substrate binding allosterically regulates proteolytic activity, and that LONP1 can adopt a configuration conducive to substrate translocation even when the ATPases are bound to ADP. These results challenge the conventional understanding of the hand-over-hand translocation mechanism, giving rise to an alternative model that aligns more closely with biochemical and biophysical data on related enzymes like ClpX, ClpA, the 26S proteasome, and Lon protease.
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Affiliation(s)
- Jeffrey T. Mindrebo
- Department of Integrative Structural and Computational Biology, Scripps Research; La Jolla, CA, USA
| | - Gabriel C. Lander
- Department of Integrative Structural and Computational Biology, Scripps Research; La Jolla, CA, USA
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2
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Sha Z, Montano MM, Rochon K, Mears JA, Deredge D, Wintrode P, Szweda L, Mikita N, Lee I. A structure and function relationship study to identify the impact of the R721G mutation in the human mitochondrial lon protease. Arch Biochem Biophys 2021; 710:108983. [PMID: 34228963 DOI: 10.1016/j.abb.2021.108983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 10/20/2022]
Abstract
Lon is an ATP-dependent protease belonging to the "ATPase associated with diverse cellular activities" (AAA+) protein family. In humans, Lon is translated as a precursor and imported into the mitochondria matrix through deletion of the first 114 amino acid residues. In mice, embryonic knockout of lon is lethal. In humans, some dysfunctional lon mutations are tolerated but they cause a developmental disorder known as the CODAS syndrome. To gain a better understanding on the enzymology of human mitochondrial Lon, this study compares the structure-function relationship of the WT versus one of the CODAS mutants R721G to identify the mechanistic features in Lon catalysis that are affected. To this end, steady-state kinetics were used to quantify the difference in ATPase and ATP-dependent peptidase activities between WT and R721G. The Km values for the intrinsic as well as protein-stimulated ATPase were increased whereas the kcat value for ATP-dependent peptidase activity was decreased in the R721G mutant. The mutant protease also displayed substrate inhibition kinetics. In vitro studies revealed that R721G did not degrade the endogenous mitochondrial Lon substrate pyruvate dehydrogenase kinase isoform 4 (PDK4) effectively like WT hLon. Furthermore, the pyruvate dehydrogenase complex (PDH) protected PDK4 from hLon degradation. Using hydrogen deuterium exchange/mass spectrometry and negative stain electron microscopy, structural perturbations associated with the R721G mutation were identified. To validate the in vitro findings under a physiologically relevant condition, the intrinsic stability as well as proteolytic activity of WT versus R721G mutant towards PDK 4 were compared in cell lysates prepared from immortalized B lymphocytes expressing the respective protease. The lifetime of PDK4 is longer in the mutant cells, but the lifetime of Lon protein is longer in the WT cells, which corroborate the in vitro structure-functional relationship findings.
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Affiliation(s)
- Zhou Sha
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Monica M Montano
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Kristy Rochon
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Jason A Mears
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA; Center for Mitochondrial Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Daniel Deredge
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, 21201, USA
| | - Patrick Wintrode
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD, 21201, USA
| | - Luke Szweda
- Department of Internal Medicine, Division of Cardiology, UT Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Natalie Mikita
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106, USA; Department of Chemistry, Missouri Western State University, St. Joseph, MO, 64507, USA.
| | - Irene Lee
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106, USA.
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3
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Gibellini L, De Gaetano A, Mandrioli M, Van Tongeren E, Bortolotti CA, Cossarizza A, Pinti M. The biology of Lonp1: More than a mitochondrial protease. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 354:1-61. [PMID: 32475470 DOI: 10.1016/bs.ircmb.2020.02.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Initially discovered as a protease responsible for degradation of misfolded or damaged proteins, the mitochondrial Lon protease (Lonp1) turned out to be a multifaceted enzyme, that displays at least three different functions (proteolysis, chaperone activity, binding of mtDNA) and that finely regulates several cellular processes, within and without mitochondria. Indeed, LONP1 in humans is ubiquitously expressed, and is involved in regulation of response to oxidative stress and, heat shock, in the maintenance of mtDNA, in the regulation of mitophagy. Furthermore, its proteolytic activity can regulate several biochemical pathways occurring totally or partially within mitochondria, such as TCA cycle, oxidative phosphorylation, steroid and heme biosynthesis and glutamine production. Because of these multiple activities, Lon protease is highly conserved throughout evolution, and mutations occurring in its gene determines severe diseases in humans, including a rare syndrome characterized by Cerebral, Ocular, Dental, Auricular and Skeletal anomalies (CODAS). Finally, alterations of LONP1 regulation in humans can favor tumor progression and aggressiveness, further highlighting the crucial role of this enzyme in mitochondrial and cellular homeostasis.
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Affiliation(s)
- Lara Gibellini
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, Modena, Italy
| | - Anna De Gaetano
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Mauro Mandrioli
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Elia Van Tongeren
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Andrea Cossarizza
- Department of Medical and Surgical Sciences of Children and Adults, University of Modena and Reggio Emilia, Modena, Italy
| | - Marcello Pinti
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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4
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Chilakala S, Cheng I, Lee I, Xu Y. Analysis of oxygen-18 labeled phosphate to study positional isotope experiments using LC-QTOF-MS. Anal Biochem 2018; 566:62-66. [PMID: 30419188 DOI: 10.1016/j.ab.2018.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 09/25/2018] [Accepted: 11/03/2018] [Indexed: 10/27/2022]
Abstract
A method is proposed in this paper for the determination of oxygen-18 labeled phosphate so that positional isotope experiments using sensitive and rapid liquid chromatography-QTOF-mass spectrometry (LC-QTOF-MS) experiments can be carried out. The positional isotope exchange technique is a useful tool in understanding the mechanisms and kinetics of many enzyme-catalyzed reactions. Detection of the positions and concentration of these exchanged isotopes is the key. Gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance imaging are commonly used analytical techniques for measurement of 18O/16O, 31P and 15N isotope enrichment. Since these techniques either require a time-consuming derivatization step or have a limited sensitivity, an LC and accurate mass-based method for monitoring 18O/16O exchange was developed and compared with a standard GC-MS method. Our results showed that the LC-QTOF-MS method developed was not only as accurate as the standard GC-MS method, but also a sensitive and robust analytical platform for the simultaneous determination of isotope enrichment and the analysis of positional isotopes without chemical derivation. The LC-QTOF-MS method developed was successfully applied to the measurement of 18O/16O in the reversibility study of ATP hydrolysis by Lon proteases.
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Affiliation(s)
- Sujatha Chilakala
- Department of Chemistry, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH, 44115, USA
| | - Iteen Cheng
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Ireen Lee
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yan Xu
- Department of Chemistry, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH, 44115, USA.
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5
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Kereïche S, Kováčik L, Bednár J, Pevala V, Kunová N, Ondrovičová G, Bauer J, Ambro Ľ, Bellová J, Kutejová E, Raška I. The N-terminal domain plays a crucial role in the structure of a full-length human mitochondrial Lon protease. Sci Rep 2016; 6:33631. [PMID: 27632940 PMCID: PMC5025710 DOI: 10.1038/srep33631] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Accepted: 08/24/2016] [Indexed: 02/02/2023] Open
Abstract
Lon is an essential, multitasking AAA+ protease regulating many cellular processes in species across all kingdoms of life. Altered expression levels of the human mitochondrial Lon protease (hLon) are linked to serious diseases including myopathies, paraplegia, and cancer. Here, we present the first 3D structure of full-length hLon using cryo-electron microscopy. hLon has a unique three-dimensional structure, in which the proteolytic and ATP-binding domains (AP-domain) form a hexameric chamber, while the N-terminal domain is arranged as a trimer of dimers. These two domains are linked by a narrow trimeric channel composed likely of coiled-coil helices. In the presence of AMP-PNP, the AP-domain has a closed-ring conformation and its N-terminal entry gate appears closed, but in ADP binding, it switches to a lock-washer conformation and its N-terminal gate opens, which is accompanied by a rearrangement of the N-terminal domain. We have also found that both the enzymatic activities and the 3D structure of a hLon mutant lacking the first 156 amino acids are severely disturbed, showing that hLon’s N-terminal domains are crucial for the overall structure of the hLon, maintaining a conformation allowing its proper functioning.
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Affiliation(s)
- Sami Kereïche
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague 2, Czech Republic
| | - Lubomír Kováčik
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague 2, Czech Republic
| | - Jan Bednár
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague 2, Czech Republic.,Université de Grenoble Alpes,CNRS UMR 5309, 38042 Grenoble Cedex 9, France
| | - Vladimír Pevala
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Nina Kunová
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Gabriela Ondrovičová
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jacob Bauer
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Ľuboš Ambro
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Bellová
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Eva Kutejová
- Department of Biochemistry and Structural Biology, Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia.,Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.,Biomedicine Center of the Academy of Sciences and Charles University in Vestec, Czech Republic
| | - Ivan Raška
- Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague 2, Czech Republic
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Lin CC, Su SC, Su MY, Liang PH, Feng CC, Wu SH, Chang CI. Structural Insights into the Allosteric Operation of the Lon AAA+ Protease. Structure 2016; 24:667-675. [PMID: 27041592 DOI: 10.1016/j.str.2016.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 02/21/2016] [Accepted: 03/04/2016] [Indexed: 11/28/2022]
Abstract
The Lon AAA+ protease (LonA) is an evolutionarily conserved protease that couples the ATPase cycle into motion to drive substrate translocation and degradation. A hallmark feature shared by AAA+ proteases is the stimulation of ATPase activity by substrates. Here we report the structure of LonA bound to three ADPs, revealing the first AAA+ protease assembly where the six protomers are arranged alternately in nucleotide-free and bound states. Nucleotide binding induces large coordinated movements of conserved pore loops from two pairs of three non-adjacent protomers and shuttling of the proteolytic groove between the ATPase site and a previously unknown Arg paddle. Structural and biochemical evidence supports the roles of the substrate-bound proteolytic groove in allosteric stimulation of ATPase activity and the conserved Arg paddle in driving substrate degradation. Altogether, this work provides a molecular framework for understanding how ATP-dependent chemomechanical movements drive allosteric processes for substrate degradation in a major protein-destruction machine.
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Affiliation(s)
- Chien-Chu Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 11529, ROC; Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan 30013, ROC
| | - Shih-Chieh Su
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 11529, ROC; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan 10617, ROC
| | - Ming-Yuan Su
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Pi-Hui Liang
- School of Pharmacy, National Taiwan University, Taipei, Taiwan 10051, ROC
| | - Chia-Cheng Feng
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 11529, ROC
| | - Shih-Hsiung Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 11529, ROC; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan 10617, ROC
| | - Chung-I Chang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan 11529, ROC; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan 10617, ROC.
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7
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Ambro Ľ, Pevala V, Ondrovičová G, Bellová J, Kunová N, Kutejová E, Bauer J. Mutations to a glycine loop in the catalytic site of human Lon changes its protease, peptidase and ATPase activities. FEBS J 2014; 281:1784-97. [PMID: 24520911 DOI: 10.1111/febs.12740] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 12/05/2013] [Accepted: 01/30/2014] [Indexed: 11/28/2022]
Abstract
UNLABELLED Lon, also called protease La, is an ATP-dependent protease present in all kingdoms of life. It is involved in protein quality control and several regulatory processes. Eukaryotic Lon possesses three domains, an N-terminal domain, an ATPase domain and a proteolytic domain. It requires ATP hydrolysis to digest larger, intact proteins, but can cleave small, fluorogenic peptides such as Glu-Ala-Ala-Phe-MNA by only binding, but not hydrolyzing, ATP. Both ATPase and peptidase activities can be stimulated by the binding of a larger protein substrate, such as β-casein. To better understand its mechanism of action, we have prepared several point mutants of four conserved residues of human Lon (G893A, G893P, G894A, G894P, G894S, G893A-G894A, G893P-G894A, G893A-G894P, T880V, W770A, W770P) and studied their ATPase, protease and peptidase activities. Our results show that mutations to Gly894 enhance its basal ATPase activity but do not change its β-casein-stimulated activity. The loop containing Gly893 and Gly894, which flanks Lon's proteolytic active site, therefore appears to be involved in the conformational change that occurs upon substrate binding. Furthermore, mutations to Trp770 have the same general effects on the ATPase activity as mutations to Gly893, indicating that Trp770 is involved in ATPase stimulation. We have also established that this loop does not need to move in order to cleave small, fluorogenic peptides, but does move during the digestion of β-casein. Finally, we also noted that Lon's ability to digest small peptides can be inhibited by moderate ATP concentrations. DATABASE Lon (Endopeptidase La), EC 4.4.21.53 STRUCTURED DIGITAL ABSTRACT: • hLonP cleaves beta casein by protease assay (1, 2, 3, 4, 5, 6) • hLon and hLon bind by cross-linking study (View interaction).
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Affiliation(s)
- Ľuboš Ambro
- Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava, Slovakia
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8
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Abstract
As the first ATP-dependent protease to be identified, Lon holds a special place in the history of cellular biology. In fact, the concept of ATP-dependent protein degradation was established through the findings that led to the discovery of Lon. Therefore, this chapter begins with a historical perspective, describing the milestones that led to the discovery of Lon and ATP-dependent proteolysis, starting from the early findings in the 1960s until the demonstration of Lon's ATP-dependent proteolytic activity in vitro, in 1981. Most of our knowledge on Lon derives from studies of the Escherichia coli Lon ortholog, and, therefore, most of this chapter relates to this particular enzyme. Nonetheless, Lon is not only found in most bacterial species, it is also found in Archaea and in the mitochondrion and chloroplast of eukaryotic cells. Therefore many of the conclusions gained from studies on the E. coli enzyme are relevant to Lon proteases in other organisms. Lon, more than any other bacterial or organellar protease, is associated with the degradation of misfolded proteins and protein quality control. In addition, Lon also degrades many regulatory proteins that are natively folded, thus it also plays a prominent role in regulation of physiological processes. Throughout the years, many Lon substrates have been identified, confirming its role in the regulation of diverse cellular processes, including cell division, DNA replication, differentiation, and adaptation to stress conditions. Some examples of these functions are described and discussed here, as is the role of Lon in the degradation of misfolded proteins and in protein quality control. Finally, this chapter deals with the exquisite sensitivity of protein degradation inside a cell. How can a protease distinguish so many substrates from cellular proteins that should not be degraded? Can the specificity of a protease be regulated according to the physiological needs of a cell? This chapter thus broadly discusses the substrate specificity of Lon and its allosteric regulation.
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Affiliation(s)
- Eyal Gur
- Life Sciences Department, Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel,
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Selwood T, Jaffe EK. Dynamic dissociating homo-oligomers and the control of protein function. Arch Biochem Biophys 2012; 519:131-43. [PMID: 22182754 PMCID: PMC3298769 DOI: 10.1016/j.abb.2011.11.020] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 11/16/2011] [Accepted: 11/28/2011] [Indexed: 11/20/2022]
Abstract
Homo-oligomeric protein assemblies are known to participate in dynamic association/disassociation equilibria under native conditions, thus creating an equilibrium of assembly states. Such quaternary structure equilibria may be influenced in a physiologically significant manner either by covalent modification or by the non-covalent binding of ligands. This review follows the evolution of ideas about homo-oligomeric equilibria through the 20th and into the 21st centuries and the relationship of these equilibria to allosteric regulation by the non-covalent binding of ligands. A dynamic quaternary structure equilibria is described where the dissociated state can have alternate conformations that cannot reassociate to the original multimer; the alternate conformations dictate assembly to functionally distinct alternate multimers of finite stoichiometry. The functional distinction between different assemblies provides a mechanism for allostery. The requirement for dissociation distinguishes this morpheein model of allosteric regulation from the classical MWC concerted and KNF sequential models. These models are described alongside earlier dissociating allosteric models. The identification of proteins that exist as an equilibrium of diverse native quaternary structure assemblies has the potential to define new targets for allosteric modulation with significant consequences for further understanding and/or controlling protein structure and function. Thus, a rationale for identifying proteins that may use the morpheein model of allostery is presented and a selection of proteins for which published data suggests this mechanism may be operative are listed.
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Affiliation(s)
- Trevor Selwood
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA, 19111
| | - Eileen K. Jaffe
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA, 19111
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Identification of a region in the N-terminus of Escherichia coli Lon that affects ATPase, substrate translocation and proteolytic activity. J Mol Biol 2012; 418:208-25. [PMID: 22387465 DOI: 10.1016/j.jmb.2012.02.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 02/21/2012] [Accepted: 02/24/2012] [Indexed: 11/24/2022]
Abstract
Lon, also known as protease La, is an AAA+ protease machine that contains the ATPase and proteolytic domain within each enzyme subunit. Three truncated Escherichia coli Lon (ELon) mutants were generated based on a previous limited tryptic digestion result and hydrogen-deuterium exchange mass spectrometry analyses performed in this study. Using methods developed for characterizing wild-type (WT) Lon, we compared the ATPase, ATP-dependent protein degradation and ATP-dependent peptidase activities. With the exception of not degrading a putative structured substrate known as CcrM (cell-cycle-regulated DNA methyltransferase), the mutant lacking the first 239 residues behaved like WT ELon. Comparing the activity data of WT and ELon mutants reveals that the first 239 residues are not needed for minimal enzyme catalysis. The mutants lacking the first 252 residues or residues 232-252 displayed compromised ATPase, protein degradation and ATP-dependent peptide translocation abilities but retained WT-like steady-state peptidase activity. The binding affinities of WT and Lon mutants were evaluated by determining the concentration of λ N (K(λN)) needed to achieve 50% maximal ATPase stimulation. Comparing the K(λN) values reveals that the region encompassing 232-252 of ELon could contribute to λ N binding, but the effect is modest. Taken together, results generated from this study reveal that the region constituting residues 240-252 of ELon is important for ATPase activity, substrate translocation and protein degradation.
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11
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Crystal structure of Lon protease: molecular architecture of gated entry to a sequestered degradation chamber. EMBO J 2010; 29:3520-30. [PMID: 20834233 DOI: 10.1038/emboj.2010.226] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 08/19/2010] [Indexed: 11/08/2022] Open
Abstract
Lon proteases are distributed in all kingdoms of life and are required for survival of cells under stress. Lon is a tandem fusion of an AAA+ molecular chaperone and a protease with a serine-lysine catalytic dyad. We report the 2.0-Å resolution crystal structure of Thermococcus onnurineus NA1 Lon (TonLon). The structure is a three-tiered hexagonal cylinder with a large sequestered chamber accessible through an axial channel. Conserved loops extending from the AAA+ domain combine with an insertion domain containing the membrane anchor to form an apical domain that serves as a gate governing substrate access to an internal unfolding and degradation chamber. Alternating AAA+ domains are in tight- and weak-binding nucleotide states with different domain orientations and intersubunit contacts, reflecting intramolecular dynamics during ATP-driven protein unfolding and translocation. The bowl-shaped proteolytic chamber is contiguous with the chaperone chamber allowing internalized proteins direct access to the proteolytic sites without further gating restrictions.
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12
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Thomas J, Fishovitz J, Lee I. Utilization of positional isotope exchange experiments to evaluate reversibility of ATP hydrolysis catalyzed by Escherichia coli Lon proteaseThis paper is one of a selection of papers published in this special issue entitled 8th International Conference on AAA Proteins and has undergone the Journal's usual peer review process. Biochem Cell Biol 2010; 88:119-28. [DOI: 10.1139/o09-117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lon protease, also known as protease La, is an ATP-dependent serine protease. Despite the presence of a proteolytic Ser–Lys dyad, the enzyme only catalyzes protein degradation in the presence of ATP. Lon possesses an intrinsic ATPase activity that is stimulated by protein and certain peptide substrates. Through sequence alignment and analysis, it is concluded that Lon belongs to the AAA+ protein family. Previous kinetic characterization of the ATPase domain of Escherichia coli Lon protease implicates a half-site reactivity model in which only 50% of the ATP bound to Lon are hydrolyzed to yield ADP; the remaining ATPase sites remain bound with ATP and are considered non-catalytic. In this model, it is implied that ATP hydrolysis is irreversible. To further evaluate the proposed half-site reactivity model, the reversibility of the ATPase activity of E. coli Lon was evaluated by positional isotope exchange experiments. The ATPase reactions were conducted in the 18O-enriched buffer such that the extent of 18O incorporation into inorganic phosphate generated from ATP hydrolysis could be used to evaluate the extent of reversibility in ATP hydrolysis. Collectively, our experimental data reveal that the ATPase reaction catalyzed by E. coli Lon in the presence and absence of peptide substrate that stimulated the enzyme’s ATPase activity is irreversible. Therefore, the half-site ATPase reactivity of E. coli Lon is validated, and can be used to account for the kinetic mechanism of the ATP-dependent peptidase activity of the enzyme.
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Affiliation(s)
- Jennifer Thomas
- WIL Research Laboratories, LLC, Ashland, OH 44805, USA
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA
| | - Jennifer Fishovitz
- WIL Research Laboratories, LLC, Ashland, OH 44805, USA
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA
| | - Irene Lee
- WIL Research Laboratories, LLC, Ashland, OH 44805, USA
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106, USA
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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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14
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Lee I, Suzuki CK. Functional mechanics of the ATP-dependent Lon protease- lessons from endogenous protein and synthetic peptide substrates. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:727-35. [PMID: 18359303 DOI: 10.1016/j.bbapap.2008.02.010] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Revised: 02/17/2008] [Accepted: 02/20/2008] [Indexed: 11/25/2022]
Abstract
Lon, also known as the protease La, is a homo-oligomeric ATP-dependent protease, which is highly conserved in archaea, eubacteria and eukaryotic mitochondria and peroxisomes. Since its discovery, studies have shown that Lon activity is essential for cellular homeostasis, mediating protein quality control and metabolic regulation. This article highlights the discoveries made over the past decade demonstrating that Lon selectively degrades abnormal as well as certain regulatory proteins and thus plays significant roles in maintaining bacterial and mitochondrial function and integrity. In addition, Lon is required in certain pathogenic bacteria, for rendering pathogenicity and host infectivity. Recent research endeavors have been directed toward elucidating the reaction mechanism of the Lon protease by different biochemical and structural biological techniques. In this mini-review, the authors survey the diverse biological roles of Lon, and also place special emphasis on recent findings that clarify the mechanistic aspects of the Lon reaction cycle.
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Affiliation(s)
- Irene Lee
- Department of Chemistry, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7078, USA.
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Licht S, Lee I. Resolving individual steps in the operation of ATP-dependent proteolytic molecular machines: from conformational changes to substrate translocation and processivity. Biochemistry 2008; 47:3595-605. [PMID: 18311925 DOI: 10.1021/bi800025g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Clp, Lon, and FtsH proteases are proteolytic molecular machines that use the free energy of ATP hydrolysis to unfold protein substrates and processively present them to protease active sites. Here we review recent biochemical and structural studies relevant to the mechanism of ATP-dependent processive proteolysis. Despite the significant structural differences among the Clp, Lon, and FtsH proteases, these enzymes share important mechanistic features. In these systems, mechanistic studies have provided evidence for ATP binding and hydrolysis-driven conformational changes that drive translocation of substrates, which has significant implications for the processive mechanism of proteolysis. These studies indicate that the nucleotide (ATP, ADP, or nonhydrolyzable ATP analogues) occupancy of the ATPase binding sites can influence the binding mode and/or binding affinity for protein substrates. A general mechanism is proposed in which the communication between ATPase active sites and protein substrate binding regions coordinates a processive cycle of substrate binding, translocation, proteolysis, and product release.
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Affiliation(s)
- Stuart Licht
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
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Patterson-Ward J, Huang J, Lee I. Detection and characterization of two ATP-dependent conformational changes in proteolytically inactive Escherichia coli Lon mutants by stopped flow kinetic techniques. Biochemistry 2007; 46:13593-605. [PMID: 17975895 DOI: 10.1021/bi701649b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Lon is an ATP dependent serine protease responsible for degrading denatured, oxidatively damaged and certain regulatory proteins in the cell. In this study we exploited the fluorescence properties of a dansylated peptide substrate (S4) and the intrinsic Trp residues in Lon to monitor peptide interacting with the enzyme. We generated two proteolytically inactive Lon mutants, S679A and S679W, where the active site serine is mutated to an Ala and Trp residue, respectively. Stopped-flow fluorescence spectroscopy was used to identify key enzyme intermediates generated along the reaction pathway prior to peptide hydrolysis. A two-step peptide binding event is detected in both mutants, where a conformational change occurs after a rapid equilibrium peptide binding step. The Kd for the initial peptide binding step determined by kinetic and equilibrium binding techniques is approximately 164 micromolar and 38 micromolar, respectively. The rate constants for the conformational change detected in the S679A and S679W Lon mutants are 0.74 +/- 0.10 s(-1) and 0.57 +/- 0.10 s(-1), respectively. These values are comparable to the lag rate constant determined for peptide hydrolysis (klag approximately 1 s(-1)) [Vineyard, D., et al. (2005) Biochemistry 45, 4602-4610]. Replacement of the active site Ser with Trp (S679W) allows for the detection of an ATP-dependent conformational change within the proteolytic site. The rate constant for this conformational change is 7.6 +/- 1.0 s(-1), and is essentially identical to the burst rate constant determined for ATP hydrolysis under comparable reaction conditions. Collectively, these kinetic data support a mechanism by which the binding of ATP to an allosteric site on Lon activates the proteolytic site. In this model, the energy derived from the binding of ATP minimally supports peptide cleavage by allowing peptide substrate access to the proteolytic site. However, the kinetics of peptide cleavage are enhanced by the hydrolysis of ATP.
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Lee I, Berdis AJ, Suzuki CK. Recent developments in the mechanistic enzymology of the ATP-dependent Lon protease from Escherichia coli: highlights from kinetic studies. MOLECULAR BIOSYSTEMS 2006; 2:477-83. [PMID: 17216028 DOI: 10.1039/b609936j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lon protease, also known as protease La, is one of the simplest ATP-dependent proteases that plays vital roles in maintaining cellular functions by selectively eliminating misfolded, damaged and certain short-lived regulatory proteins. Although Lon is a homo-oligomer, each subunit of Lon contains both an ATPase and a protease active site. This relatively simple architecture compared to other hetero-oligomeric ATP-dependent proteases such as the proteasome makes Lon a useful paradigm for studying the mechanism of ATP-dependent proteolysis. In this article, we survey some recent developments in the mechanistic characterization of Lon with an emphasis on the utilization of pre-steady-state enzyme kinetic techniques to determine the timing of the ATPase and peptidase activities of the enzyme.
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Affiliation(s)
- Irene Lee
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
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