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Kuzminov A. Bacterial nucleoid is a riddle wrapped in a mystery inside an enigma. J Bacteriol 2024; 206:e0021123. [PMID: 38358278 PMCID: PMC10994824 DOI: 10.1128/jb.00211-23] [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] [Indexed: 02/16/2024] Open
Abstract
Bacterial chromosome, the nucleoid, is traditionally modeled as a rosette of DNA mega-loops, organized around proteinaceous central scaffold by nucleoid-associated proteins (NAPs), and mixed with the cytoplasm by transcription and translation. Electron microscopy of fixed cells confirms dispersal of the cloud-like nucleoid within the ribosome-filled cytoplasm. Here, I discuss evidence that the nucleoid in live cells forms DNA phase separate from riboprotein phase, the "riboid." I argue that the nucleoid-riboid interphase, where DNA interacts with NAPs, transcribing RNA polymerases, nascent transcripts, and ssRNA chaperones, forms the transcription zone. An active part of phase separation, transcription zone enforces segregation of the centrally positioned information phase (the nucleoid) from the surrounding action phase (the riboid), where translation happens, protein accumulates, and metabolism occurs. I speculate that HU NAP mostly tiles up the nucleoid periphery-facilitating DNA mobility but also supporting transcription in the interphase. Besides extruding plectonemically supercoiled DNA mega-loops, condensins could compact them into solenoids of uniform rings, while HU could support rigidity and rotation of these DNA rings. The two-phase cytoplasm arrangement allows the bacterial cell to organize the central dogma activities, where (from the cell center to its periphery) DNA replicates and segregates, DNA is transcribed, nascent mRNA is handed over to ribosomes, mRNA is translated into proteins, and finally, the used mRNA is recycled into nucleotides at the inner membrane. The resulting information-action conveyor, with one activity naturally leading to the next one, explains the efficiency of prokaryotic cell design-even though its main intracellular transportation mode is free diffusion.
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Affiliation(s)
- Andrei Kuzminov
- Department of Microbiology, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
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2
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Son A, Huizar Cabral V, Huang Z, Litberg TJ, Horowitz S. G-quadruplexes rescuing protein folding. Proc Natl Acad Sci U S A 2023; 120:e2216308120. [PMID: 37155907 PMCID: PMC10194009 DOI: 10.1073/pnas.2216308120] [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: 09/23/2022] [Accepted: 04/12/2023] [Indexed: 05/10/2023] Open
Abstract
Maintaining the health of the proteome is a critical cellular task. Recently, we found G-quadruplex (G4) nucleic acids are especially potent at preventing protein aggregation in vitro and could at least indirectly improve the protein folding environment of Escherichia coli. However, the roles of G4s in protein folding were not yet explored. Here, through in vitro protein folding experiments, we discover that G4s can accelerate protein folding by rescuing kinetically trapped intermediates to both native and near-native folded states. Time-course folding experiments in E. coli further demonstrate that these G4s primarily improve protein folding quality in E. coli as opposed to preventing protein aggregation. The ability of a short nucleic acid to rescue protein folding opens up the possibility of nucleic acids and ATP-independent chaperones to play considerable roles in dictating the ultimate folding fate of proteins.
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Affiliation(s)
- Ahyun Son
- Department of Chemistry & Biochemistry, Knoebel Institute for Healthy Aging, University of Denver, Denver, CO80208
| | - Veronica Huizar Cabral
- Department of Chemistry & Biochemistry, Knoebel Institute for Healthy Aging, University of Denver, Denver, CO80208
| | - Zijue Huang
- Department of Chemistry & Biochemistry, Knoebel Institute for Healthy Aging, University of Denver, Denver, CO80208
| | - Theodore J. Litberg
- Department of Chemistry & Biochemistry, Knoebel Institute for Healthy Aging, University of Denver, Denver, CO80208
| | - Scott Horowitz
- Department of Chemistry & Biochemistry, Knoebel Institute for Healthy Aging, University of Denver, Denver, CO80208
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3
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Zhang H, Chen C, Yang Z, Ye L, Miao J, Lan Y, Wang Q, Ye Z, Cao Y, Liu G. Combined transcriptomic and proteomic analysis of the antibacterial mechanisms of an antimicrobial substance produced by Lactobacillus paracasei FX-6 against colistin-resistant Escherichia coli. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2022.114394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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4
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Catalytic cycling of human mitochondrial Lon protease. Structure 2022; 30:1254-1268.e7. [PMID: 35870450 DOI: 10.1016/j.str.2022.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 03/21/2022] [Accepted: 06/28/2022] [Indexed: 11/20/2022]
Abstract
The mitochondrial Lon protease (LonP1) regulates mitochondrial health by removing redundant proteins from the mitochondrial matrix. We determined LonP1 in eight nucleotide-dependent conformational states by cryoelectron microscopy (cryo-EM). The flexible assembly of N-terminal domains had 3-fold symmetry, and its orientation depended on the conformational state. We show that a conserved structural motif around T803 with a high similarity to the trypsin catalytic triad is essential for proteolysis. We show that LonP1 is not regulated by redox potential, despite the presence of two conserved cysteines at disulfide-bonding distance in its unfoldase core. Our data indicate how sequential ATP hydrolysis controls substrate protein translocation in a 6-fold binding change mechanism. Substrate protein translocation, rather than ATP hydrolysis, is a rate-limiting step, suggesting that LonP1 is a Brownian ratchet with ATP hydrolysis preventing translocation reversal. 3-fold rocking motions of the flexible N-domain assembly may assist thermal unfolding of the substrate protein.
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5
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Mitochondrial HSP70 Chaperone System-The Influence of Post-Translational Modifications and Involvement in Human Diseases. Int J Mol Sci 2021; 22:ijms22158077. [PMID: 34360841 PMCID: PMC8347752 DOI: 10.3390/ijms22158077] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 01/25/2023] Open
Abstract
Since their discovery, heat shock proteins (HSPs) have been identified in all domains of life, which demonstrates their importance and conserved functional role in maintaining protein homeostasis. Mitochondria possess several members of the major HSP sub-families that perform essential tasks for keeping the organelle in a fully functional and healthy state. In humans, the mitochondrial HSP70 chaperone system comprises a central molecular chaperone, mtHSP70 or mortalin (HSPA9), which is actively involved in stabilizing and importing nuclear gene products and in refolding mitochondrial precursor proteins, and three co-chaperones (HSP70-escort protein 1-HEP1, tumorous imaginal disc protein 1-TID-1, and Gro-P like protein E-GRPE), which regulate and accelerate its protein folding functions. In this review, we summarize the roles of mitochondrial molecular chaperones with particular focus on the human mtHsp70 and its co-chaperones, whose deregulated expression, mutations, and post-translational modifications are often considered to be the main cause of neurological disorders, genetic diseases, and malignant growth.
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6
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Yang S, Franden MA, Wang X, Chou YC, Hu Y, Brown SD, Pienkos PT, Zhang M. Transcriptomic Profiles of Zymomonas mobilis 8b to Furfural Acute and Long-Term Stress in Both Glucose and Xylose Conditions. Front Microbiol 2020; 11:13. [PMID: 32038596 PMCID: PMC6989614 DOI: 10.3389/fmicb.2020.00013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 01/06/2020] [Indexed: 12/14/2022] Open
Abstract
Zymomonas mobilis 8b is an ethanologenic bacterium engineered to utilize both glucose and xylose. The impacts of lignocellulosic hydrolyzate inhibitors on the growth of Zymomonas mobilis 8b have been investigated. However, the molecular responses of these inhibitors have not been completely elucidated yet. In this study, molecular responses to furfural were investigated using transcriptomic approaches of both chip-based microarray and a directional mRNA-Seq. Furfural acute shock time-course experiment with 3 g/L furfural supplemented when cells reached exponential phase and stress response experiment in the presence of 2 g/L furfural from the beginning of fermentation were carried out to study the physiological and transcriptional profiles of short-term and long-term effects of furfural on 8b. Furfural negatively affected 8b growth in terms of final biomass and the fermentation time. Transcriptomic studies indicated that the response of 8b to furfural was dynamic and complex, and differences existed between short-term shock and long-term stress responses. However, the gene function categories were similar with most down-regulated genes related to translation and biosynthesis, while the furfural up-regulated genes were mostly related to general stress responses. Several gene candidates have been identified and genetic studies indicated that expression of ZMO0465 and cysteine synthase operon ZMO0003-0006 driven by its native promoter in a shuttle vector enhanced the furfural tolerance of 8b. In addition, the relationship between microarray and mRNA-Seq was compared with good correlations. The directional mRNA-Seq data not only provided the gene expression profiling, but also can be applied for transcriptional architecture improvement to identify and confirm operons, novel transcripts, hypothetical gene functions, transcriptional start sites, and promoters with different strength.
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Affiliation(s)
- Shihui Yang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China.,National Bioenergy and Biosciences Centers, National Renewable Energy Laboratory, Golden, CO, United States
| | - Mary Ann Franden
- National Bioenergy and Biosciences Centers, National Renewable Energy Laboratory, Golden, CO, United States
| | - Xia Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China
| | - Yat-Chen Chou
- National Bioenergy and Biosciences Centers, National Renewable Energy Laboratory, Golden, CO, United States
| | - Yun Hu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Environmental Microbial Technology Center of Hubei Province, School of Life Sciences, Hubei University, Wuhan, China
| | - Steven D Brown
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, United States.,BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - Philip T Pienkos
- National Bioenergy and Biosciences Centers, National Renewable Energy Laboratory, Golden, CO, United States
| | - Min Zhang
- National Bioenergy and Biosciences Centers, National Renewable Energy Laboratory, Golden, CO, United States
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Improvement in the Orthogonal Protein Degradation in Escherichia coli by Truncated mf-ssrA Tag. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s12209-019-00193-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Abstract
Regulated proteolysis is a vital process that affects all living things. Bacteria use energy-dependent AAA+ proteases to power degradation of misfolded and native regulatory proteins. Given that proteolysis is an irreversible event, specificity and selectivity in degrading substrates are key. Specificity is often augmented through the use of adaptors that modify the inherent specificity of the proteolytic machinery. Regulated protein degradation is intricately linked to quality control, cell-cycle progression, and physiological transitions. In this review, we highlight recent work that has shed light on our understanding of regulated proteolysis in bacteria. We discuss the role AAA+ proteases play during balanced growth as well as how these proteases are deployed during changes in growth. We present examples of how protease selectivity can be controlled in increasingly complex ways. Finally, we describe how coupling a core recognition determinant to one or more modifying agents is a general theme for regulated protein degradation.
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Affiliation(s)
- Samar A Mahmoud
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA; ,
| | - Peter Chien
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA; ,
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9
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Wang X, Khushk I, Xiao Y, Gao Q, Bao J. Tolerance improvement of Corynebacterium glutamicum on lignocellulose derived inhibitors by adaptive evolution. Appl Microbiol Biotechnol 2017; 102:377-388. [DOI: 10.1007/s00253-017-8627-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/24/2017] [Accepted: 11/06/2017] [Indexed: 01/09/2023]
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10
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Mitochondrial Nucleoid: Shield and Switch of the Mitochondrial Genome. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:8060949. [PMID: 28680532 PMCID: PMC5478868 DOI: 10.1155/2017/8060949] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 03/06/2017] [Accepted: 04/03/2017] [Indexed: 11/18/2022]
Abstract
Mitochondria preserve very complex and distinctively unique machinery to maintain and express the content of mitochondrial DNA (mtDNA). Similar to chromosomes, mtDNA is packaged into discrete mtDNA-protein complexes referred to as a nucleoid. In addition to its role as a mtDNA shield, over 50 nucleoid-associated proteins play roles in mtDNA maintenance and gene expression through either temporary or permanent association with mtDNA or other nucleoid-associated proteins. The number of mtDNA(s) contained within a single nucleoid is a fundamental question but remains a somewhat controversial issue. Disturbance in nucleoid components and mutations in mtDNA were identified as significant in various diseases, including carcinogenesis. Significant interest in the nucleoid structure and its regulation has been stimulated in relation to mitochondrial diseases, which encompass diseases in multicellular organisms and are associated with accumulation of numerous mutations in mtDNA. In this review, mitochondrial nucleoid structure, nucleoid-associated proteins, and their regulatory roles in mitochondrial metabolism are briefly addressed to provide an overview of the emerging research field involving mitochondrial biology.
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11
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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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Spiridonova VA, Kudzhaev AM, Melnichuk AV, Gainutdinov AA, Andrianova AG, Rotanova TV. [Interaction of DNA Aptamers with the ATP-Dependent Lon Protease from Escherichia coli]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2016; 41:696-700. [PMID: 27125023 DOI: 10.1134/s1068162015060151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ATP-dependent Lon protease of E. coli (Ec-Lon) is a key enzyme of the quality control system of the cell proteome. Ec-Lon subunit comprises N-terminal non-catalytic region, ATPase module and proteolytic domain (serine-lysine endopeptidase). A distinctive feature of the Ec-Lon is its ability to interact with DNA, however either DNA binding site(s) or the role ofthe complex Ec-Lon · DNA have not yet been characterized. A promising tool for the study of molecular mechanisms of interaction between nucleic acids and protein ligands are known to be aptamers (small nucleic acids with high specificity to organic compounds of different nature). Ec-Lon-protease was found to form complexes with the previously obtained thrombin aptamers whose molecules comprise the duplex domains and G-quadruplex region. The aptamer affinities to the enzyme have been characterized. The synthesis of novel aptamers specific to Ec-Lon protease is planed for studying the mechanism of the enzyme-DNA complexation.
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Pinti M, Gibellini L, Nasi M, De Biasi S, Bortolotti CA, Iannone A, Cossarizza A. Emerging role of Lon protease as a master regulator of mitochondrial functions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1300-1306. [PMID: 27033304 DOI: 10.1016/j.bbabio.2016.03.025] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/23/2016] [Accepted: 03/24/2016] [Indexed: 11/29/2022]
Abstract
Lon protease is a nuclear-encoded, mitochondrial ATP-dependent protease highly conserved throughout the evolution, crucial for the maintenance of mitochondrial homeostasis. Lon acts as a chaperone of misfolded proteins, and is necessary for maintaining mitochondrial DNA. The impairment of these functions has a deep impact on mitochondrial functionality and morphology. An altered expression of Lon leads to a profound reprogramming of cell metabolism, with a switch from respiration to glycolysis, which is often observed in cancer cells. Mutations of Lon, which likely impair its chaperone properties, are at the basis of a genetic inherited disease named of the cerebral, ocular, dental, auricular, skeletal (CODAS) syndrome. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.
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Affiliation(s)
- Marcello Pinti
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Lara Gibellini
- Department of Surgery, Medicine, Dentistry and Morphological Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Milena Nasi
- Department of Surgery, Medicine, Dentistry and Morphological Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Sara De Biasi
- Department of Surgery, Medicine, Dentistry and Morphological Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Anna Iannone
- Department of Diagnostics, Clinical and Public Health Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | - Andrea Cossarizza
- Department of Surgery, Medicine, Dentistry and Morphological Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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14
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Simons M, Diffin FM, Szczelkun MD. ClpXP protease targets long-lived DNA translocation states of a helicase-like motor to cause restriction alleviation. Nucleic Acids Res 2014; 42:12082-91. [PMID: 25260590 PMCID: PMC4231737 DOI: 10.1093/nar/gku851] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
We investigated how Escherichia coli ClpXP targets the helicase-nuclease (HsdR) subunit of the bacterial Type I restriction–modification enzyme EcoKI during restriction alleviation (RA). RA is a temporary reduction in endonuclease activity that occurs when Type I enzymes bind unmodified recognition sites on the host genome. These conditions arise upon acquisition of a new system by a naïve host, upon generation of new sites by genome rearrangement/mutation or during homologous recombination between hemimethylated DNA. Using recombinant DNA and proteins in vitro, we demonstrate that ClpXP targets EcoKI HsdR during dsDNA translocation on circular DNA but not on linear DNA. Protein roadblocks did not activate HsdR proteolysis. We suggest that DNA translocation lifetime, which is elevated on circular DNA relative to linear DNA, is important to RA. To identify the ClpX degradation tag (degron) in HsdR, we used bioinformatics and biochemical assays to design N- and C-terminal mutations that were analysed in vitro and in vivo. None of the mutants produced a phenotype consistent with loss of the degron, suggesting an as-yet-unidentified recognition pathway. We note that an EcoKI nuclease mutant still produces cell death in a clpx− strain, consistent with DNA damage induced by unregulated motor activity.
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Affiliation(s)
- Michelle Simons
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Fiona M Diffin
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
| | - Mark D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK
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15
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Gilkerson R, Bravo L, Garcia I, Gaytan N, Herrera A, Maldonado A, Quintanilla B. The mitochondrial nucleoid: integrating mitochondrial DNA into cellular homeostasis. Cold Spring Harb Perspect Biol 2013; 5:a011080. [PMID: 23637282 DOI: 10.1101/cshperspect.a011080] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The packaging of mitochondrial DNA (mtDNA) into DNA-protein assemblies called nucleoids provides an efficient segregating unit of mtDNA, coordinating mtDNA's involvement in cellular metabolism. From the early discovery of mtDNA as "extranuclear" genetic material, its organization into nucleoids and integration into both the mitochondrial organellar network and the cell at large via a variety of signal transduction pathways, mtDNA is a crucial component of the cell's homeostatic network. The mitochondrial nucleoid is composed of a set of DNA-binding core proteins involved in mtDNA maintenance and transcription, and a range of peripheral factors, which are components of signaling pathways controlling mitochondrial biogenesis, metabolism, apoptosis, and retrograde mitochondria-to-nucleus signaling. The molecular interactions of nucleoid components with the organellar network and cellular signaling pathways provide exciting clues to the dynamic integration of mtDNA into cellular metabolic homeostasis.
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Affiliation(s)
- Robert Gilkerson
- Department of Biology, University of Texas-Pan American, Edinburg, TX 78539-2999, USA.
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16
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Krupinska K, Melonek J, Krause K. New insights into plastid nucleoid structure and functionality. PLANTA 2013; 237:653-64. [PMID: 23212213 DOI: 10.1007/s00425-012-1817-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 11/09/2012] [Indexed: 05/04/2023]
Abstract
Investigations over many decades have revealed that nucleoids of higher plant plastids are highly dynamic with regard to their number, their structural organization and protein composition. Membrane attachment and environmental cues seem to determine the activity and functionality of the nucleoids and point to a highly regulated structure-function relationship. The heterogeneous composition and the many functions that are seemingly associated with the plastid nucleoids could be related to the high number of chromosomes per plastid. Recent proteomic studies have brought novel nucleoid-associated proteins into the spotlight and indicated that plastid nucleoids are an evolutionary hybrid possessing prokaryotic nucleoid features and eukaryotic (nuclear) chromatin components, several of which are dually targeted to the nucleus and chloroplasts. Future studies need to unravel if and how plastid-nucleus communication depends on nucleoid structure and plastid gene expression.
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Affiliation(s)
- Karin Krupinska
- Institute of Botany, University of Kiel, Olshausenstraße 40, 24098, Kiel, Germany.
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