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Luo G, Ming T, Yang L, He L, Tao T, Wang Y. Modulators targeting protein-protein interactions in Mycobacterium tuberculosis. Microbiol Res 2024; 284:127675. [PMID: 38636239 DOI: 10.1016/j.micres.2024.127675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 04/20/2024]
Abstract
Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis), mainly transmitted through droplets to infect the lungs, and seriously affecting patients' health and quality of life. Clinically, anti-TB drugs often entail side effects and lack efficacy against resistant strains. Thus, the exploration and development of novel targeted anti-TB medications are imperative. Currently, protein-protein interactions (PPIs) offer novel avenues for anti-TB drug development, and the study of targeted modulators of PPIs in M. tuberculosis has become a prominent research focus. Furthermore, a comprehensive PPI network has been constructed using computational methods and bioinformatics tools. This network allows for a more in-depth analysis of the structural biology of PPIs and furnishes essential insights for the development of targeted small-molecule modulators. Furthermore, this article provides a detailed overview of the research progress and regulatory mechanisms of PPI modulators in M. tuberculosis, the causative agent of TB. Additionally, it summarizes potential targets for anti-TB drugs and discusses the prospects of existing PPI modulators.
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Affiliation(s)
- Guofeng Luo
- School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Tianqi Ming
- State Key Laboratory of Southwestern Chinese Medicine Resources, Department of Pharmacology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Luchuan Yang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Lei He
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Tao Tao
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Yanmei Wang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China.
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2
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Yang Y, Zhao N, Xu X, Zhou Y, Luo B, Zhang J, Sui J, Huang J, Qiu Z, Zhang X, Zeng J, Bai L, Bao R, Luo Y. Discovery and Mechanistic Study of Novel Mycobacterium tuberculosis ClpP1P2 Inhibitors. J Med Chem 2023; 66:16597-16614. [PMID: 38088921 DOI: 10.1021/acs.jmedchem.3c01054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Caseinolytic protease P (ClpP) responsible for the proteolysis of damaged or misfolded proteins plays a critical role in proteome homeostasis. MtbClpP1P2, a ClpP enzyme complex, is required for survival in Mycobacterium tuberculosis, and it is therefore considered as a promising target for the development of antituberculosis drugs. Here, we discovered that cediranib and some of its derivatives are potent MtbClpP1P2 inhibitors and suppress M. tuberculosis growth. Protein pull-down and loss-of-function assays validated the in situ targeting of MtbClpP1P2 by cediranib and its active derivatives. Structural and mutational studies revealed that cediranib binds to MtbClpP1P2 by binding to an allosteric pocket at the equatorial handle domain of the MtbClpP1 subunit, which represents a unique binding mode compared to other known ClpP modulators. These findings provide us insights for rational drug design of antituberculosis therapies and implications for our understanding of the biological activity of MtbClpP1P2.
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Affiliation(s)
- Yang Yang
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
- Capital Institute of Pediatrics, Beijing 100020, PR China
| | - Ninglin Zhao
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Xin Xu
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Yuanzheng Zhou
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Baozhu Luo
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Jiangnan Zhang
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Jing Sui
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Jiasheng Huang
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Zhiqiang Qiu
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Xuelian Zhang
- School of Life Science, Fudan University, Shanghai 200438, PR China
| | - Jumei Zeng
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Lang Bai
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Rui Bao
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
| | - Youfu Luo
- Division of Infectious Diseases, State Key Laboratory of Biotherapy and Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, PR China
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Ogbonna EC, Anderson HR, Beardslee PC, Bheemreddy P, Schmitz KR. Interactome Analysis Identifies MSMEI_3879 as a Substrate of Mycolicibacterium smegmatis ClpC1. Microbiol Spectr 2023; 11:e0454822. [PMID: 37341639 PMCID: PMC10433963 DOI: 10.1128/spectrum.04548-22] [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: 11/08/2022] [Accepted: 05/31/2023] [Indexed: 06/22/2023] Open
Abstract
The prevalence of drug-resistant Mycobacterium tuberculosis infections has prompted extensive efforts to exploit new drug targets in this globally important pathogen. ClpC1, the unfoldase component of the essential ClpC1P1P2 protease, has emerged as one particularly promising antibacterial target. However, efforts to identify and characterize compounds that impinge on ClpC1 activity are constrained by our limited knowledge of Clp protease function and regulation. To expand our understanding of ClpC1 physiology, we employed a coimmunoprecipitation and mass spectrometry workflow to identify proteins that interact with ClpC1 in Mycolicibacterium smegmatis, a surrogate for M. tuberculosis. We identify a diverse panel of interaction partners, many of which coimmunoprecipitate with both the regulatory N-terminal domain and the ATPase core of ClpC1. Notably, our interactome analysis establishes MSMEI_3879, a truncated gene product unique to M. smegmatis, as a novel proteolytic substrate. Degradation of MSMEI_3879 by ClpC1P1P2 in vitro requires exposure of its N-terminal sequence, reinforcing the idea that ClpC1 selectively recognizes disordered motifs on substrates. Fluorescent substrates incorporating MSMEI_3879 may be useful in screening for novel ClpC1-targeting antibiotics to help address the challenge of M. tuberculosis drug resistance. IMPORTANCE Drug-resistant tuberculosis infections are a major challenge to global public health. Much effort has been invested in identifying new drug targets in the causative pathogen, Mycobacterium tuberculosis. One such target is the ClpC1 unfoldase. Compounds have been identified that kill M. tuberculosis by disrupting ClpC1 activity, yet the physiological function of ClpC1 in cells has remained poorly defined. Here, we identify interaction partners of ClpC1 in a model mycobacterium. By building a broader understanding of the role of this prospective drug target, we can more effectively develop compounds that inhibit its essential cellular activities.
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Affiliation(s)
- Emmanuel C. Ogbonna
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
| | - Henry R. Anderson
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA
| | - Patrick C. Beardslee
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA
| | - Priyanka Bheemreddy
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
| | - Karl R. Schmitz
- Department of Biological Sciences, University of Delaware, Newark, Delaware, USA
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, USA
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4
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Jiang J, Schmitz KR. Bioinformatic identification of ClpI, a distinct class of Clp unfoldases in Actinomycetota. Front Microbiol 2023; 14:1161764. [PMID: 37138635 PMCID: PMC10149685 DOI: 10.3389/fmicb.2023.1161764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 03/24/2023] [Indexed: 05/05/2023] Open
Abstract
All clades of bacteria possess Hsp100/Clp family unfoldase enzymes that contribute to aspects of protein quality control. In Actinomycetota, these include ClpB, which functions as an independent chaperone and disaggregase, and ClpC, which cooperates with the ClpP1P2 peptidase to carry out regulated proteolysis of client proteins. We initially sought to algorithmically catalog Clp unfoldase orthologs from Actinomycetota into ClpB and ClpC categories. In the process, we uncovered a phylogenetically distinct third group of double-ringed Clp enzymes, which we term ClpI. ClpI enzymes are architecturally similar to ClpB and ClpC, with intact ATPase modules and motifs associated with substrate unfolding and translation. While ClpI possess an M-domain similar in length to that of ClpC, its N-terminal domain is more variable than the strongly conserved N-terminal domain of ClpC. Surprisingly, ClpI sequences are divisible into sub-classes that either possess or lack the LGF-motifs required for stable assembly with ClpP1P2, suggesting distinct cellular roles. The presence of ClpI enzymes likely provides bacteria with expanded complexity and regulatory control over protein quality control programs, supplementing the conserved roles of ClpB and ClpC.
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Affiliation(s)
- Jialiu Jiang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States
| | - Karl R. Schmitz
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, United States
- Department of Biological Sciences, University of Delaware, Newark, DE, United States
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Cazzaniga G, Mori M, Chiarelli LR, Gelain A, Meneghetti F, Villa S. Natural products against key Mycobacterium tuberculosis enzymatic targets: Emerging opportunities for drug discovery. Eur J Med Chem 2021; 224:113732. [PMID: 34399099 DOI: 10.1016/j.ejmech.2021.113732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/15/2021] [Accepted: 07/28/2021] [Indexed: 11/16/2022]
Abstract
For centuries, natural products (NPs) have served as powerful therapeutics against a variety of human ailments. Nowadays, they still represent invaluable resources for the treatment of many diseases, including bacterial infections. After nearly three decades since the World Health Organization's (WHO) declaration of tuberculosis (TB) as a global health emergency, Mycobacterium tuberculosis (Mtb) continues to claim millions of lives, remaining among the leading causes of death worldwide. In the last years, several efforts have been devoted to shortening and improving treatment outcomes, and to overcoming the increasing resistance phenomenon. Nature has always provided a virtually unlimited source of bioactive molecules, which have inspired the development of new drugs. NPs are characterized by an exceptional chemical and structural diversity, the result of millennia of evolutionary responses to various stimuli. Thanks to their favorable structural features and their enzymatic origin, they are naturally prone to bind proteins and exhibit bioactivities. Furthermore, their worldwide distribution and ease of accessibility has contributed to promote investigations on their activity. Overall, these characteristics make NPs excellent models for the design of novel therapeutics. This review offers a critical and comprehensive overview of the most promising NPs, isolated from plants, fungi, marine species, and bacteria, endowed with inhibitory properties against traditional and emerging mycobacterial enzymatic targets. A selection of 86 compounds is here discussed, with a special emphasis on their biological activity, structure-activity relationships, and mechanism of action. Our study corroborates the antimycobacterial potential of NPs, substantiating their relevance in future drug discovery and development efforts.
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Affiliation(s)
- Giulia Cazzaniga
- Department of Pharmaceutical Sciences, University of Milan, via L. Mangiagalli 25, 20133, Milano, Italy
| | - Matteo Mori
- Department of Pharmaceutical Sciences, University of Milan, via L. Mangiagalli 25, 20133, Milano, Italy
| | - Laurent Roberto Chiarelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, via A. Ferrata 9, 27100, Pavia, Italy
| | - Arianna Gelain
- Department of Pharmaceutical Sciences, University of Milan, via L. Mangiagalli 25, 20133, Milano, Italy
| | - Fiorella Meneghetti
- Department of Pharmaceutical Sciences, University of Milan, via L. Mangiagalli 25, 20133, Milano, Italy.
| | - Stefania Villa
- Department of Pharmaceutical Sciences, University of Milan, via L. Mangiagalli 25, 20133, Milano, Italy
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Brötz-Oesterhelt H, Vorbach A. Reprogramming of the Caseinolytic Protease by ADEP Antibiotics: Molecular Mechanism, Cellular Consequences, Therapeutic Potential. Front Mol Biosci 2021; 8:690902. [PMID: 34109219 PMCID: PMC8182300 DOI: 10.3389/fmolb.2021.690902] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022] Open
Abstract
Rising antibiotic resistance urgently calls for the discovery and evaluation of novel antibiotic classes and unique antibiotic targets. The caseinolytic protease Clp emerged as an unprecedented target for antibiotic therapy 15 years ago when it was observed that natural product-derived acyldepsipeptide antibiotics (ADEP) dysregulated its proteolytic core ClpP towards destructive proteolysis in bacterial cells. A substantial database has accumulated since on the interaction of ADEP with ClpP, which is comprehensively compiled in this review. On the molecular level, we describe the conformational control that ADEP exerts over ClpP, the nature of the protein substrates degraded, and the emerging structure-activity-relationship of the ADEP compound class. On the physiological level, we review the multi-faceted antibacterial mechanism, species-dependent killing modes, the activity against carcinogenic cells, and the therapeutic potential of the compound class.
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Affiliation(s)
- Heike Brötz-Oesterhelt
- Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tübingen, Germany.,Cluster of Excellence: Controlling Microbes to Fight Infection, Tübingen, Germany
| | - Andreas Vorbach
- Microbial Bioactive Compounds, Interfaculty Institute of Microbiology and Infection Medicine, University of Tuebingen, Tübingen, Germany
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Zhang H, Hsu HC, Kahne SC, Hara R, Zhan W, Jiang X, Burns-Huang K, Ouellette T, Imaeda T, Okamoto R, Kawasaki M, Michino M, Wong TT, Toita A, Yukawa T, Moraca F, Vendome J, Saha P, Sato K, Aso K, Ginn J, Meinke PT, Foley M, Nathan CF, Darwin KH, Li H, Lin G. Macrocyclic Peptides that Selectively Inhibit the Mycobacterium tuberculosis Proteasome. J Med Chem 2021; 64:6262-6272. [PMID: 33949190 PMCID: PMC8194371 DOI: 10.1021/acs.jmedchem.1c00296] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Treatment of tuberculosis (TB) currently takes at least 6 months. Latent Mycobacterium tuberculosis (Mtb) is phenotypically tolerant to most anti-TB drugs. A key hypothesis is that drugs that kill nonreplicating (NR) Mtb may shorten treatment when used in combination with conventional drugs. The Mtb proteasome (Mtb20S) could be such a target because its pharmacological inhibition kills NR Mtb and its genetic deletion renders Mtb unable to persist in mice. Here, we report a series of macrocyclic peptides that potently and selectively target the Mtb20S over human proteasomes, including macrocycle 6. The cocrystal structure of macrocycle 6 with Mtb20S revealed structural bases for the species selectivity. Inhibition of 20S within Mtb by 6 dose dependently led to the accumulation of Pup-tagged GFP that is degradable but resistant to depupylation and death of nonreplicating Mtb under nitrosative stress. These results suggest that compounds of this class have the potential to develop as anti-TB therapeutics.
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Affiliation(s)
- Hao Zhang
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - Hao-Chi Hsu
- Department of Structural Biology, Van Andel Institute, 333 Bostwick Ave. NE, Grand Rapids, MI 49503
| | - Shoshanna C. Kahne
- Department of Microbiology, New York University School of Medicine, 430 E. 29th Street, New York, NY 10016
| | - Ryoma Hara
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Wenhu Zhan
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - Xiuju Jiang
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - Kristin Burns-Huang
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - Tierra Ouellette
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - Toshihiro Imaeda
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Rei Okamoto
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Masanori Kawasaki
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Mayako Michino
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Tzu-Tshin Wong
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Akinori Toita
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Takafumi Yukawa
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | | | | | - Priya Saha
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - Kenjiro Sato
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Kazuyoshi Aso
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - John Ginn
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Peter T. Meinke
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Michael Foley
- Tri-Institutional Therapeutics Discovery Institute, 413 E. 69th St, New York, NY 10065
| | - Carl F Nathan
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
| | - K. Heran Darwin
- Department of Microbiology, New York University School of Medicine, 430 E. 29th Street, New York, NY 10016
| | - Huilin Li
- Department of Structural Biology, Van Andel Institute, 333 Bostwick Ave. NE, Grand Rapids, MI 49503
| | - Gang Lin
- Department of Microbiology & Immunology, Weill Cornell Medicine, 1300 York Ave., New York, NY 10065
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Acyldepsipeptide activated ClpP1P2 macromolecule of Leptospira, an ideal Achilles' heel to hamper the cell survival and deregulate ClpP proteolytic activity. Res Microbiol 2021; 172:103797. [PMID: 33460738 DOI: 10.1016/j.resmic.2021.103797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/30/2020] [Accepted: 01/07/2021] [Indexed: 11/22/2022]
Abstract
Antibiotic acyldepsipeptide (ADEP) targets the bacterial ClpP serine protease and can inhibit the growth of numerous bacterial species by activating/dysregulating the protease activity within the cell. The spirochete Leptospira interrogans harbors two ClpP isoforms (LepClpP1 and LepClpP2). Supplementation of ADEP in the Leptospira growth medium resulted in the inhibition of bacterial growth. The ADEP mediated activation of the LepClpP mixture was dependent on the time allowed for the self-assembly of LepClpP1 and LepClpP2. The dynamic light scattering of the LepClpP mixture in the presence of the ADEP indicated a conformational transformation of the LepClpP machinery. Serine 98, a catalytic triad residue of the LepClpP1 in the LepClpP1P2 heterocomplex, was critical for the ADEP mediated activation. The computational prototype of the LepClpP1P2 structure suggested that the hydrophobic pockets wherein the ADEPs or the physiological chaperone ClpX predominantly dock are exclusively present in the LepClpP2 heptamer. Using the ADEP as a tool, this investigation provides an insight into the molecular function of the LepClpP1P2 in a coalition with its ATPase chaperone LepClpX. The shreds of the evidence illustrated in this investigation verify that ADEP1 possesses the ability to control the LepClpP system in an unconventional approach than the other organisms.
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Mycobacterium smegmatis MSMEG_0129 is a nutrition-associated regulator that interacts with CarD and ClpP2. Int J Biochem Cell Biol 2020; 124:105763. [PMID: 32389745 DOI: 10.1016/j.biocel.2020.105763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 04/14/2020] [Accepted: 04/29/2020] [Indexed: 12/16/2022]
Abstract
Mycobacterium smegmatis MSMEG_0129 and Rv0164, its homologue in Mycobacterium tuberculosis, are single START-domain proteins essential for bacterial growth and survival, but their biochemical activities and biological roles remain undetermined. Here, we probed the possible functions of MSMEG_0129 and its underlying mechanisms by determining its cellular location, searching for its interaction partners and monitoring its transcription profile. MSMEG_0129, and Rv0164 by extension, were found to be cytosolic proteins rather than secreted components as previously understood. Increases in MSMEG_0129 expression at physiological levels accelerated bacterial growth in a proportional manner, but additional growth acceleration was not observed when MSMEG_0129 was overexpressed up to 20 fold. MSMEG_0129 is a short-lived protein, unstable at both the mRNA and protein levels. Co-IP and GST pull-down assays showed that MSMEG_0129 interacts with the ClpP2 protease and a global transcription factor, CarD, their expression being correlated with that of MSMEG_0129. Nutrient deficiency led to the downregulation of MSMEG_0129 but upregulation of CarD. However, in the context of constitutive MSMEG_0129 overexpression under nutrient-rich or starvation conditions, the mRNA level of CarD was reduced 3 fold. Conversely, expression of ClpP2 decreased with MSMEG_0129 downregulation under starvation conditions, but increased 4-8 fold when MSMEG_0129 was overexpressed. Our data suggest that MSMEG_0129, and Rv0164 by analogy, are likely to be nutrition sensing factors that regulate mycobacterial growth and may be involved in signal transfer under nutrient deficiency, possibly via physical and regulatory interactions with CarD and ClpP2.
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