1
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Nishiyama A, Shimizu M, Narita T, Kodera N, Ozeki Y, Yokoyama A, Mayanagi K, Yamaguchi T, Hakamata M, Shaban A, Tateishi Y, Ito K, Matsumoto S. Dynamic action of an intrinsically disordered protein in DNA compaction that induces mycobacterial dormancy. Nucleic Acids Res 2024; 52:816-830. [PMID: 38048321 PMCID: PMC10810275 DOI: 10.1093/nar/gkad1149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 10/17/2023] [Accepted: 11/23/2023] [Indexed: 12/06/2023] Open
Abstract
Mycobacteria are the major human pathogens with the capacity to become dormant persisters. Mycobacterial DNA-binding protein 1 (MDP1), an abundant histone-like protein in dormant mycobacteria, induces dormancy phenotypes, e.g. chromosome compaction and growth suppression. For these functions, the polycationic intrinsically disordered region (IDR) is essential. However, the disordered property of IDR stands in the way of clarifying the molecular mechanism. Here we clarified the molecular and structural mechanism of DNA compaction by MDP1. Using high-speed atomic force microscopy, we observed that monomeric MDP1 bundles two adjacent DNA duplexes side-by-side via IDR. Combined with coarse-grained molecular dynamics simulation, we revealed the novel dynamic DNA cross-linking model of MDP1 in which a stretched IDR cross-links two DNA duplexes like double-sided tape. IDR is able to hijack HU function, resulting in the induction of strong mycobacterial growth arrest. This IDR-mediated reversible DNA cross-linking is a reasonable model for MDP1 suppression of the genomic function in the resuscitable non-replicating dormant mycobacteria.
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Affiliation(s)
- Akihito Nishiyama
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
| | - Masahiro Shimizu
- Nano Life Science Institute, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa 920-1192, Japan
- Division of Quantum Beam Material Science, Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2 Asashiro-Nishi, Kumatori, Sennan-gun, Osaka 590-0494, Japan
| | - Tomoyuki Narita
- Nano Life Science Institute, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa 920-1192, Japan
| | - Noriyuki Kodera
- Nano Life Science Institute, Kanazawa University, Kakumamachi, Kanazawa, Ishikawa 920-1192, Japan
| | - Yuriko Ozeki
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
| | - Akira Yokoyama
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
- Department of Respiratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Kouta Mayanagi
- Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Takehiro Yamaguchi
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
- Department of Pharmacology, Osaka Metropolitan University Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan
| | - Mariko Hakamata
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
- Department of Respiratory Medicine and Infectious Disease, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
| | - Amina Kaboso Shaban
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
| | - Yoshitaka Tateishi
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
| | - Kosuke Ito
- Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan
| | - Sohkichi Matsumoto
- Department of Bacteriology, Niigata University School of Medicine, 1-757 Asahimachi-dori, Chuo-ku, Niigata 951-8510, Japan
- Laboratory of Tuberculosis, Institute of Tropical Disease, Universitas Airlangga, Kampus C Jl. Mulyorejo, Surabaya, East Java 60115, Indonesia
- Division of Research Aids, Hokkaido University Institute for Vaccine Research & Development, Kita 20, Nishi 10, Kita-ku, Sapporo, 001-0020, Japan
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2
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Gupta A, Joshi A, Arora K, Mukhopadhyay S, Guptasarma P. The bacterial nucleoid-associated proteins, HU, and Dps, condense DNA into context-dependent biphasic or multiphasic complex coacervates. J Biol Chem 2023; 299:104637. [PMID: 36963493 PMCID: PMC10141540 DOI: 10.1016/j.jbc.2023.104637] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 02/27/2023] [Accepted: 03/08/2023] [Indexed: 03/26/2023] Open
Abstract
The bacterial chromosome, known as its nucleoid, is an amorphous assemblage of globular nucleoprotein domains. It exists in a state of phase separation from the cell's cytoplasm, as an irregularly-shaped, membrane-less, intracellular compartment. This state (the nature of which remains largely unknown) is maintained through bacterial generations ad infinitum. Here, we show that HU, and Dps, two of the most abundant nucleoid-associated proteins (NAPs) of Escherichia coli, undergo spontaneous complex coacervation with different forms of DNA/RNA, both individually and in each other's presence, to cause accretion and compaction of DNA/RNA into liquid-liquid phase separated (LLPS) condensates in vitro. Upon mixing with nucleic acids, HU-A and HU-B form (a) bi-phasic heterotypic mixed condensates in which HU-B helps to lower the Csat of HU-A; and also (b) multi-phasic heterotypic condensates, with Dps, in which de-mixed domains display different contents of HU and Dps. We believe that these modes of complex coacervation that are seen in vitro can serve as models for the in vivo relationships amongst NAPs in nucleoids, involving local and global variations in the relative abundances of the different NAPs, especially in de-mixed sub-domains that are characterized by differing grades of phase separation. Our results clearly demonstrate some quantitative, and some qualitative, differences in the coacervating abilities of different NAPs with DNA, potentially explaining (i) why E. coli has two isoforms of HU, and (ii) why changes in the abundances of HU and Dps facilitate the lag, logarithmic and stationary phases of E. coli growth.
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Affiliation(s)
- Archit Gupta
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.
| | - Ashish Joshi
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Kanika Arora
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Samrat Mukhopadhyay
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Chemical Sciences; Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India
| | - Purnananda Guptasarma
- Centre for Protein Science, Design and Engineering, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India; Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.
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3
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Wasim A, Gupta A, Bera P, Mondal J. Interpretation of organizational role of proteins on E. coli nucleoid via Hi-C integrated model. Biophys J 2023; 122:63-81. [PMID: 36435970 PMCID: PMC9822802 DOI: 10.1016/j.bpj.2022.11.2938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/23/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022] Open
Abstract
Several proteins in Escherichia coli work together to maintain the complex organization of its chromosome. However, the individual roles of these so-called nucleoid-associated proteins (NAPs) in chromosome architectures are not well characterized. Here, we quantitatively dissect the organizational roles of Heat Unstable (HU), a ubiquitous protein in E. coli and MatP, an NAP specifically binding to the Ter macrodomain of the chromosome. Toward this end, we employ a polymer physics-based computer model of wild-type chromosome and their HU- and MatP-devoid counterparts by incorporating their respective experimentally derived Hi-C contact matrix, cell dimensions, and replication status of the chromosome commensurate with corresponding growth conditions. Specifically, our model for the HU-devoid chromosome corroborates well with the microscopy observation of compaction of chromosome at short genomic range but diminished long-range interactions, justifying precedent hypothesis of segregation defect upon HU removal. Control simulations point out that the change in cell dimension and chromosome content in the process of HU removal holds the key to the observed differences in chromosome architecture between wild-type and HU-devoid cells. On the other hand, simulation of MatP-devoid chromosome led to locally enhanced contacts between Ter and its flanking macrodomains, consistent with previous recombination assay experiments and MatP's role in insulation of the Ter macrodomain from the rest of the chromosome. However, the simulation indicated no change in matS sites' localization. Rather, a set of designed control simulations showed that insulation of Ter is not caused by bridging of distant matS sites, also lending credence to a recent mobility experiment on various loci of the E. coli chromosome. Together, the investigations highlight the ability of an integrative model of the bacterial genome in elucidating the role of NAPs and in reconciling multiple experimental observations.
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Affiliation(s)
- Abdul Wasim
- Tata Institute of Fundamental Research, Hyderabad, India
| | - Ankit Gupta
- Tata Institute of Fundamental Research, Hyderabad, India
| | - Palash Bera
- Tata Institute of Fundamental Research, Hyderabad, India
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4
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Agapova YK, Petrenko DE, Timofeev VI, Rakitina TV. Comparative Analysis of the Interfaces between Monomers in the Dimers of Bacterial Histone-Like HU Proteins by the MM-GBSA Method. CRYSTALLOGR REP+ 2022. [DOI: 10.1134/s1063774522060025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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5
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Barlow VL, Tsai YH. Acetylation at Lysine 86 of Escherichia coli HUβ Modulates the DNA-Binding Capability of the Protein. Front Microbiol 2022; 12:809030. [PMID: 35185833 PMCID: PMC8854993 DOI: 10.3389/fmicb.2021.809030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/24/2021] [Indexed: 11/13/2022] Open
Abstract
DNA-binding protein HU is highly conserved in bacteria and has been implicated in a range of cellular processes and phenotypes. Like eukaryotic histones, HU is subjected to post-translational modifications. Specifically, acetylation of several lysine residues have been reported in both homologs of Escherichia coli HU. Here, we investigated the effect of acetylation at Lys67 and Lys86, located in the DNA binding-loop and interface of E. coli HUβ, respectively. Using the technique of genetic code expansion, homogeneous HUβ(K67ac) and HUβ(K86ac) protein units were obtained. Acetylation at Lys86 seemed to have negligible effects on protein secondary structure and thermal stability. Nevertheless, we found that this site-specific acetylation can regulate DNA binding by the HU homodimer but not the heterodimer. Intriguingly, while Lys86 acetylation reduced the interaction of the HU homodimer with short double-stranded DNA containing a 2-nucleotide gap or nick, it enhanced the interaction with longer DNA fragments and had minimal effect on a short, fully complementary DNA fragment. These results demonstrate the complexity of post-translational modifications in functional regulation, as well as indicating the role of lysine acetylation in tuning bacterial gene transcription and epigenetic regulation.
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Affiliation(s)
| | - Yu-Hsuan Tsai
- School of Chemistry, Cardiff University, Cardiff, United Kingdom
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, China
- *Correspondence: Yu-Hsuan Tsai,
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6
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Jin R, Grasso M, Zhou M, Marmorstein R, Baumgart T. Unfolding Mechanisms and Conformational Stability of the Dimeric Endophilin N-BAR Domain. ACS OMEGA 2021; 6:20790-20803. [PMID: 34423187 PMCID: PMC8374900 DOI: 10.1021/acsomega.1c01905] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/13/2021] [Indexed: 06/13/2023]
Abstract
Endophilin, which is a member of the Bin-amphiphysin-Rvs (BAR) domain protein superfamily, contains a homodimeric N-BAR domain of a characteristic crescent shape. The N-BAR domain comprises a six-helix bundle and is known to sense and generate membrane curvature. Here, we characterize aspects of the unfolding mechanism of the endophilin A1 N-BAR domain during thermal denaturation and examine factors that influence the thermal stability of this domain. Far-UV circular dichroism (CD) spectroscopy was applied to monitor changes in the secondary structure above room temperature. The protein's conformational changes were further characterized through Foerster resonance energy transfer and cross-linking experiments at varying temperatures. Our results indicate that thermal unfolding of the endophilin N-BAR is (minimally) a two-step process, with a dimeric intermediate that displays partial helicity loss. Furthermore, a thermal shift assay and temperature-dependent CD were applied to compare the unfolding processes of several truncated versions of endophilin. The melting temperature of the N-BAR domain decreased when we deleted either the N-terminal H0 helix or the unstructured linker of endophilin. This result suggests that these intrinsically disordered domains may play a role in structurally stabilizing the functional N-BAR domain in vivo. Finally, we show that single-site mutations can also compromise endophilin's thermal stability.
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Affiliation(s)
- Rui Jin
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Michael Grasso
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department
of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Mingyang Zhou
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Abramson
Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Ronen Marmorstein
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Department
of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
- Abramson
Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Tobias Baumgart
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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7
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Amemiya HM, Schroeder J, Freddolino PL. Nucleoid-associated proteins shape chromatin structure and transcriptional regulation across the bacterial kingdom. Transcription 2021; 12:182-218. [PMID: 34499567 PMCID: PMC8632127 DOI: 10.1080/21541264.2021.1973865] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/15/2021] [Accepted: 08/18/2021] [Indexed: 01/21/2023] Open
Abstract
Genome architecture has proven to be critical in determining gene regulation across almost all domains of life. While many of the key components and mechanisms of eukaryotic genome organization have been described, the interplay between bacterial DNA organization and gene regulation is only now being fully appreciated. An increasing pool of evidence has demonstrated that the bacterial chromosome can reasonably be thought of as chromatin, and that bacterial chromosomes contain transcriptionally silent and transcriptionally active regions analogous to heterochromatin and euchromatin, respectively. The roles played by histones in eukaryotic systems appear to be shared across a range of nucleoid-associated proteins (NAPs) in bacteria, which function to compact, structure, and regulate large portions of bacterial chromosomes. The broad range of extant NAPs, and the extent to which they differ from species to species, has raised additional challenges in identifying and characterizing their roles in all but a handful of model bacteria. Here we review the regulatory roles played by NAPs in several well-studied bacteria and use the resulting state of knowledge to provide a working definition for NAPs, based on their function, binding pattern, and expression levels. We present a screening procedure which can be applied to any species for which transcriptomic data are available. Finally, we note that NAPs tend to play two major regulatory roles - xenogeneic silencers and developmental regulators - and that many unrecognized potential NAPs exist in each bacterial species examined.
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Affiliation(s)
- Haley M. Amemiya
- University of Michigan Medical School, Ann Arbor, MI, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jeremy Schroeder
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L. Freddolino
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
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8
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Esener N, Maciel-Guerra A, Giebel K, Lea D, Green MJ, Bradley AJ, Dottorini T. Mass spectrometry and machine learning for the accurate diagnosis of benzylpenicillin and multidrug resistance of Staphylococcus aureus in bovine mastitis. PLoS Comput Biol 2021; 17:e1009108. [PMID: 34115749 PMCID: PMC8221797 DOI: 10.1371/journal.pcbi.1009108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/23/2021] [Accepted: 05/22/2021] [Indexed: 01/16/2023] Open
Abstract
Staphylococcus aureus is a serious human and animal pathogen threat exhibiting extraordinary capacity for acquiring new antibiotic resistance traits in the pathogen population worldwide. The development of fast, affordable and effective diagnostic solutions capable of discriminating between antibiotic-resistant and susceptible S. aureus strains would be of huge benefit for effective disease detection and treatment. Here we develop a diagnostics solution that uses Matrix-Assisted Laser Desorption/Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF) and machine learning, to identify signature profiles of antibiotic resistance to either multidrug or benzylpenicillin in S. aureus isolates. Using ten different supervised learning techniques, we have analysed a set of 82 S. aureus isolates collected from 67 cows diagnosed with bovine mastitis across 24 farms. For the multidrug phenotyping analysis, LDA, linear SVM, RBF SVM, logistic regression, naïve Bayes, MLP neural network and QDA had Cohen's kappa values over 85.00%. For the benzylpenicillin phenotyping analysis, RBF SVM, MLP neural network, naïve Bayes, logistic regression, linear SVM, QDA, LDA, and random forests had Cohen's kappa values over 85.00%. For the benzylpenicillin the diagnostic systems achieved up to (mean result ± standard deviation over 30 runs on the test set): accuracy = 97.54% ± 1.91%, sensitivity = 99.93% ± 0.25%, specificity = 95.04% ± 3.83%, and Cohen's kappa = 95.04% ± 3.83%. Moreover, the diagnostic platform complemented by a protein-protein network and 3D structural protein information framework allowed the identification of five molecular determinants underlying the susceptible and resistant profiles. Four proteins were able to classify multidrug-resistant and susceptible strains with 96.81% ± 0.43% accuracy. Five proteins, including the previous four, were able to classify benzylpenicillin resistant and susceptible strains with 97.54% ± 1.91% accuracy. Our approach may open up new avenues for the development of a fast, affordable and effective day-to-day diagnostic solution, which would offer new opportunities for targeting resistant bacteria.
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MESH Headings
- Animals
- Bacterial Proteins/chemistry
- Cattle
- Computational Biology
- Diagnosis, Computer-Assisted/methods
- Diagnosis, Computer-Assisted/statistics & numerical data
- Diagnosis, Computer-Assisted/veterinary
- Drug Resistance, Multiple, Bacterial
- Female
- Humans
- Mastitis, Bovine/diagnosis
- Mastitis, Bovine/drug therapy
- Mastitis, Bovine/microbiology
- Methicillin-Resistant Staphylococcus aureus/chemistry
- Methicillin-Resistant Staphylococcus aureus/drug effects
- Methicillin-Resistant Staphylococcus aureus/isolation & purification
- Microbial Sensitivity Tests
- Models, Molecular
- Penicillin G/pharmacology
- Protein Interaction Maps
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Staphylococcal Infections/diagnosis
- Staphylococcal Infections/drug therapy
- Staphylococcal Infections/veterinary
- Staphylococcus aureus/chemistry
- Staphylococcus aureus/drug effects
- Staphylococcus aureus/isolation & purification
- Supervised Machine Learning
- United Kingdom
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Affiliation(s)
- Necati Esener
- University of Nottingham, School of Veterinary Medicine and Science, Sutton Bonington, United Kingdom
| | - Alexandre Maciel-Guerra
- University of Nottingham School of Computer Science, Jubilee Campus, Nottingham, United Kingdom
| | | | - Daniel Lea
- Digital Research Service, University of Nottingham, Sutton Bonington, United Kingdom
| | - Martin J. Green
- University of Nottingham, School of Veterinary Medicine and Science, Sutton Bonington, United Kingdom
| | - Andrew J. Bradley
- University of Nottingham, School of Veterinary Medicine and Science, Sutton Bonington, United Kingdom
- Quality Milk Management Services ltd, Easton, United Kingdom
| | - Tania Dottorini
- University of Nottingham, School of Veterinary Medicine and Science, Sutton Bonington, United Kingdom
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9
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Arora K, Thakur B, Mrigwani A, Guptasarma P. N-Terminal Extensions Appear to Frustrate HU Heterodimer Formation by Strengthening Intersubunit Contacts and Blocking the Formation of a Heterotetrameric Intermediate. Biochemistry 2021; 60:1836-1852. [PMID: 34015918 DOI: 10.1021/acs.biochem.1c00081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
HU is a bacterial nucleoid-associated protein. Two homologues, known as HU-A, and HU-B, are found in Escherichia coli within which the early, late, and stationary phases of growth are dominated by HU-AA, HU-BB, and HU-AB dimers, respectively. Here, using genetic manipulation, mass spectrometry, spectroscopy, chromatography, and electrophoretic examination of glutaraldehyde-mediated cross-linking of subunits, in combination with experiments involving mixing, co-expression, unfolding, and refolding of HU chains, we show that the spontaneous formation of HU-AB heterodimers that is reported to occur upon mixing of wild-type HU-AA and HU-BB homodimers does not occur if chains possess N-terminal extensions. We show that N-terminal extensions interfere with the conversion of homodimers into heterodimers. We also show that heterodimers are readily formed at anticipated levels by chains possessing N-terminal extensions in vivo, when direct chain-chain interactions are facilitated through production of HU-A and HU-B chains from proximal genes located upon the same plasmid. From the data, two explanations emerge regarding the mechanism by which N-terminal extensions happen to adversely affect the conversion of homodimers into heterodimers. (1) The disappearance of the α-amino group at HU's N-terminus impacts the intersubunit stacking of β-sheets at HU's dimeric interface, reducing the ease with which subunits dissociate from each other. Simultaneously, (2) the presence of an N-terminal extension appears to sterically prevent the association of HU-AA and HU-BB homodimers into a critically required, heterotetrameric intermediate (within which homodimers could otherwise exchange subunits without releasing monomers into solution, by remaining physically associated with each other).
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Affiliation(s)
- Kanika Arora
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab 140306, India
| | - Bhishem Thakur
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab 140306, India
| | - Arpita Mrigwani
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab 140306, India
| | - Purnananda Guptasarma
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab 140306, India
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10
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Arora K, Thakur B, Gupta A, Guptasarma P. HU-AB simulacrum: Fusion of HU-B and HU-A into HU-B-A, a functional analog of the Escherichia coli HU-AB heterodimer. Biochem Biophys Res Commun 2021; 560:27-31. [PMID: 33964504 DOI: 10.1016/j.bbrc.2021.04.107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 04/26/2021] [Indexed: 11/19/2022]
Abstract
In enteric bacteria such as Escherichia coli, there are two homologs of the DNA-binding nucleoid associated protein (NAP) known as HU. The two homologs are known as HU-A and HU-B, and exist either in the form of homodimers (HU-AA, or HU-BB) or as heterodimers (HU-AB), with different propensities to form higher-order oligomers. The three different dimeric forms dominate different stages of bacterial growth, with the HU-AB heterodimer dominating cultures in the stationary phase. Due to similarities in their properties, and the facile equilibrium that exists between the dimeric forms, the dimers are difficult to purify away from each other. Although HU-AA and HU-BB can be purified through extensive ion-exchange chromatography, reestablishment of equilibrium interferes with the purification of the HU-AB heterodimer (which constitutes ∼90% of any population with equal numbers of HU-B and HU-A chains). Here, we report the creation of a functional analog of HU-AB that does not appear to partition to generate any minority populations of HU-AA or HU-BB. The analog was constructed through genetic fusion of the HU-B and HU-A chains into a single polypeptide (HU-B-A) with a glycine/serine-rich linker of 11 amino acids separating HU-B from HU-A, and a histidine tag at the N-terminus of HU-B. HU-B-A folds to bind 4-way junction DNA, and displays a significant tendency to form dimers (i.e., analogs of HU tetramers), and a higher thermodynamic stability than HU-BB or HU-AA, thus explaining why it dominates mixtures of HU-B and HU-A chains.
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Affiliation(s)
- Kanika Arora
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India
| | - Bhishem Thakur
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India
| | - Archit Gupta
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India
| | - Purnananda Guptasarma
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India.
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11
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Thakur B, Gupta A, Guptasarma P. A novel protein-engineered dsDNA-binding protein (HU-Simulacrum) inspired by HU, a nucleoid-associated DNABII protein. Biochem Biophys Res Commun 2020; 534:47-52. [PMID: 33310187 DOI: 10.1016/j.bbrc.2020.11.088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 11/21/2020] [Indexed: 11/30/2022]
Abstract
HU, a DNA-binding protein, has a helical N-terminal region (NTR) of ∼44 residues and a beta strand- and IDR-rich C-terminal region (CTR) of ∼46 residues. CTR binds to DNA through (i) a clasp (two arginine/lysine-rich, IDR-rich beta hairpins that bind to phosphate groups in the minor groove), (ii) a flat surface (comprising four antiparallel beta strands that abut the major groove), and (iii) a charge cluster (two lysine residues upon a short C-terminal helix). HU forms a dimer displaying extensive inter-subunit CTR-CTR contacts. A single-chain simulacrum of these contacts (HU-Simul) incorporating all DNA-binding elements was created by fusing together the CTRs of Escherichia coli HU-A and Thermus thermophilus HU. HU-Simul is monomeric, binds to dsDNA and cruciform DNA, but not to ssDNA.
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Affiliation(s)
- Bhishem Thakur
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India.
| | - Archit Gupta
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India
| | - Purnananda Guptasarma
- Centre for Protein Science, Design and Engineering (CPSDE), Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Mohali, Knowledge City, Sector-81, SAS Nagar, Punjab, 140306, India.
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12
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Chen SWW, Banneville AS, Teulon JM, Timmins J, Pellequer JL. Nanoscale surface structures of DNA bound to Deinococcus radiodurans HU unveiled by atomic force microscopy. NANOSCALE 2020; 12:22628-22638. [PMID: 33150905 DOI: 10.1039/d0nr05320a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Deinococcus radiodurans protein HU (DrHU) was shown to be critical for nucleoid activities, yet its functional and structural properties remain largely unexplored. We have applied atomic force microscopy (AFM) imaging to study DrHU binding to pUC19-DNA in vitro and analyzed the topographic structures formed at the nanoscale. At the single-molecule level, AFM imaging allows visualization of super-helical turns on naked DNA surfaces and characterization of free DrHU molecules observed as homodimers. When enhancing the molecular surface structures of AFM images by the Laplacian weight filter, the distribution of bound DrHUs was visibly varied as a function of the DrHU/DNA molar ratio. At a low molar ratio, DrHU binding was found to reduce the volume of condensed DNA configuration by about 50%. We also show that DrHU is capable of bridging distinct DNA segments. Moreover, at a low molar ratio, the binding orientation of individual DrHU dimers could be perceived on partially "open" DNA configuration. At a high molar ratio, DrHU stiffened the DNA molecule and enlarged the spread of the open DNA configuration. Furthermore, a lattice-like pattern could be seen on the surface of DrHU-DNA complex, indicating that DrHU multimerization had occurred leading to the formation of a higher order architecture. Together, our results show that the functional plasticity of DrHU in mediating DNA organization is subject to both the conformational dynamics of DNA molecules and protein abundance.
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Affiliation(s)
- Shu-Wen W Chen
- Univ. Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale (IBS), F-38000 Grenoble, France.
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13
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The structural basis of African swine fever virus pA104R binding to DNA and its inhibition by stilbene derivatives. Proc Natl Acad Sci U S A 2020; 117:11000-11009. [PMID: 32358196 DOI: 10.1073/pnas.1922523117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
African swine fever virus (ASFV) is a highly contagious nucleocytoplasmic large DNA virus (NCLDV) that causes nearly 100% mortality in swine. The development of effective vaccines and drugs against this virus is urgently needed. pA104R, an ASFV-derived histone-like protein, shares sequence and functional similarity with bacterial HU/IHF family members and is essential for viral replication. Herein, we solved the crystal structures of pA104R in its apo state as well as in complex with DNA. Apo-pA104R forms a homodimer and folds into an architecture conserved in bacterial heat-unstable nucleoid proteins/integration host factors (HUs/IHFs). The pA104R-DNA complex structure, however, uncovers that pA104R has a DNA binding pattern distinct from its bacterial homologs, that is, the β-ribbon arms of pA104R stabilize DNA binding by contacting the major groove instead of the minor groove. Mutations of the basic residues at the base region of the β-strand DNA binding region (BDR), rather than those in the β-ribbon arms, completely abolished DNA binding, highlighting the major role of the BDR base in DNA binding. An overall DNA bending angle of 93.8° is observed in crystal packing of the pA104R-DNA complex structure, which is close to the DNA bending angle in the HU-DNA complex. Stilbene derivatives SD1 and SD4 were shown to disrupt the binding between pA104R and DNA and inhibit the replication of ASFV in primary porcine alveolar macrophages. Collectively, these results reveal the structural basis of pA104R binding to DNA highlighting the importance of the pA104R-DNA interaction in the ASFV replication cycle and provide inhibitor leads for ASFV chemotherapy.
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14
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Georgoulis A, Louka M, Mylonas S, Stavros P, Nounesis G, Vorgias CE. Consensus protein engineering on the thermostable histone-like bacterial protein HUs significantly improves stability and DNA binding affinity. Extremophiles 2020; 24:293-306. [PMID: 31980943 DOI: 10.1007/s00792-020-01154-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 01/06/2020] [Indexed: 11/28/2022]
Abstract
Consensus-based protein engineering strategy has been applied to various proteins and it can lead to the design of proteins with enhanced biological performance. Histone-like HUs comprise a protein family with sequence variety within a highly conserved 3D-fold. HU function includes compacting and regulating bacterial DNA in a wide range of biological conditions in bacteria. To explore the possible impact of consensus-based design in the thermodynamic stability of HU proteins, the approach was applied using a dataset of sequences derived from a group of 40 mesostable, thermostable, and hyperthermostable HUs. The consensus-derived HU protein was named HUBest, since it is expected to perform best. The synthetic HU gene was overexpressed in E. coli and the recombinant protein was purified. Subsequently, HUBest was characterized concerning its correct folding and thermodynamic stability, as well as its ability to interact with plasmid DNA. A substantial increase in HUBest stability at high temperatures is observed. HUBest has significantly improved biological performance at ambience temperature, presenting very low Kd values for binding plasmid DNA as indicated from the Gibbs energy profile of HUBest. This Kd may be associated to conformational changes leading to decreased thermodynamic stability and, therefore, higher flexibility at ambient temperature.
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Affiliation(s)
- Anastasios Georgoulis
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, 157 01, Zografou, Greece
| | - Maria Louka
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, 157 01, Zografou, Greece
| | - Stratos Mylonas
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, 157 01, Zografou, Greece
| | - Philemon Stavros
- Biomolecular Physics Laboratory, INRASTES, National Centre for Scientific Research "Demokritos", 153 10, Agia Paraskevi, Greece
| | - George Nounesis
- Biomolecular Physics Laboratory, INRASTES, National Centre for Scientific Research "Demokritos", 153 10, Agia Paraskevi, Greece
| | - Constantinos E Vorgias
- Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, 157 01, Zografou, Greece.
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15
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Stojkova P, Spidlova P, Stulik J. Nucleoid-Associated Protein HU: A Lilliputian in Gene Regulation of Bacterial Virulence. Front Cell Infect Microbiol 2019; 9:159. [PMID: 31134164 PMCID: PMC6523023 DOI: 10.3389/fcimb.2019.00159] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 04/26/2019] [Indexed: 12/29/2022] Open
Abstract
Nucleoid-associated proteins belong to a group of small but abundant proteins in bacterial cells. These transcription regulators are responsible for many important cellular processes and also are involved in pathogenesis of bacteria. The best-known nucleoid-associated proteins, such as HU, FIS, H-NS, and IHF, are often discussed. The most important findings in research concerning HU protein are described in this mini review. Its roles in DNA compaction, shape modulation, and negative supercoiling induction have been studied intensively. HU protein regulates bacteria survival, growth, SOS response, virulence genes expression, cell division, and many other cell processes. Elucidating the mechanism of HU protein action has been the subject of many research projects. This mini review provides a comprehensive overview of the HU protein.
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Affiliation(s)
| | - Petra Spidlova
- Department of Molecular Pathology and Biology, Faculty of Military Health Sciences, University of Defence, Hradec Kralove, Czechia
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16
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Beaufour M, Ginguené D, Le Meur R, Castaing B, Cadene M. Liquid Native MALDI Mass Spectrometry for the Detection of Protein-Protein Complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1981-1994. [PMID: 30066268 PMCID: PMC6153977 DOI: 10.1007/s13361-018-2015-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/14/2018] [Accepted: 06/19/2018] [Indexed: 05/29/2023]
Abstract
Native mass spectrometry (MS) encompasses methods to keep noncovalent interactions of biomolecular complexes intact in the gas phase throughout the instrument and to measure the mass-to-charge ratios of supramolecular complexes directly in the mass spectrometer. Electrospray ionization (ESI) in nondenaturing conditions is now an established method to characterize noncovalent systems. Matrix-assisted laser desorption/ionization (MALDI), on the other hand, consumes low quantities of samples and largely tolerates contaminants, making it a priori attractive for native MS. However, so-called native MALDI approaches have so far been based on solid deposits, where the rapid transition of the sample through a solid state can engender the loss of native conformations. Here we present a new method for native MS based on liquid deposits and MALDI ionization, unambiguously detecting intact noncovalent protein complexes by direct desorption from a liquid spot for the first time. To control for aggregation, we worked with HUαβ, a heterodimer that does not spontaneously rearrange into homodimers in solution. Screening through numerous matrix solutions to observe first the monomeric protein, then the dimer complex, we settled on a nondenaturing binary matrix solution composed of acidic and basic organic matrices in glycerol, which is stable in vacuo. The role of temporal and spatial laser irradiation patterns was found to be critical. Both a protein-protein and a protein-ligand complex could be observed free of aggregation. To minimize gas-phase dissociation, source parameters were optimized to achieve a conservation of complexes above 50% for both systems. Graphical Abstract ᅟ.
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Affiliation(s)
- Martine Beaufour
- Centre de Biophysique Moléculaire, UPR4301, CNRS, affiliated to Université d'Orléans, Rue Charles Sadron, 45071, Orléans Cedex 2, France
| | - David Ginguené
- Centre de Biophysique Moléculaire, UPR4301, CNRS, affiliated to Université d'Orléans, Rue Charles Sadron, 45071, Orléans Cedex 2, France
| | - Rémy Le Meur
- Centre de Biophysique Moléculaire, UPR4301, CNRS, affiliated to Université d'Orléans, Rue Charles Sadron, 45071, Orléans Cedex 2, France
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Bertrand Castaing
- Centre de Biophysique Moléculaire, UPR4301, CNRS, affiliated to Université d'Orléans, Rue Charles Sadron, 45071, Orléans Cedex 2, France
| | - Martine Cadene
- Centre de Biophysique Moléculaire, UPR4301, CNRS, affiliated to Université d'Orléans, Rue Charles Sadron, 45071, Orléans Cedex 2, France.
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17
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Kamashev D, Agapova Y, Rastorguev S, Talyzina AA, Boyko KM, Korzhenevskiy DA, Vlaskina A, Vasilov R, Timofeev VI, Rakitina TV. Comparison of histone-like HU protein DNA-binding properties and HU/IHF protein sequence alignment. PLoS One 2017; 12:e0188037. [PMID: 29131864 PMCID: PMC5683647 DOI: 10.1371/journal.pone.0188037] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/12/2017] [Indexed: 12/12/2022] Open
Abstract
Background The structure and function of bacterial nucleoid are controlled by histone-like proteins of HU/IHF family, omnipresent in bacteria and also founding archaea and some eukaryotes.HU protein binds dsDNA without sequence specificity and avidly binds DNA structures with propensity to be inclined such as forks, three/four-way junctions, nicks, overhangs and DNA bulges. Sequence comparison of thousands of known histone-like proteins from diverse bacteria phyla reveals relation between HU/IHF sequence, DNA–binding properties and other protein features. Methodology and principal findings Performed alignment and clusterization of the protein sequences show that HU/IHF family proteins can be unambiguously divided into three groups, HU proteins, IHF_A and IHF_B proteins. HU proteins, IHF_A and IHF_B proteins are further partitioned into several clades for IHF and HU; such a subdivision is in good agreement with bacterial taxonomy. We also analyzed a hundred of 3D fold comparative models built for HU sequences from all revealed HU clades. It appears that HU fold remains similar in spite of the HU sequence variations. We studied DNA–binding properties of HU from N. gonorrhoeae, which sequence is similar to one of E.coli HU, and HU from M. gallisepticum and S. melliferum which sequences are distant from E.coli protein. We found that in respect to dsDNA binding, only S. melliferum HU essentially differs from E.coli HU. In respect to binding of distorted DNA structures, S. melliferum HU and E.coli HU have similar properties but essentially different from M. gallisepticum HU and N. gonorrhea HU. We found that in respect to dsDNA binding, only S. melliferum HU binds DNA in non-cooperative manner and both mycoplasma HU bend dsDNA stronger than E.coli and N. gonorrhoeae. In respect to binding to distorted DNA structures, each HU protein has its individual profile of affinities to various DNA-structures with the increased specificity to DNA junction. Conclusions and significance HU/IHF family proteins sequence alignment and classification are updated. Comparative modeling demonstrates that HU protein 3D folding’s even more conservative than HU sequence. For the first time, DNA binding characteristics of HU from N. gonorrhoeae, M. gallisepticum and S. melliferum are studied. Here we provide detailed analysis of the similarity and variability of DNA-recognizing and bending of four HU proteins from closely and distantly related HU clades.
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Affiliation(s)
- Dmitri Kamashev
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
- * E-mail:
| | - Yulia Agapova
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
| | - Sergey Rastorguev
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
| | - Anna A. Talyzina
- Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russian Federation
| | - Konstantin M. Boyko
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russian Federation
| | - Dmitry A. Korzhenevskiy
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
| | - Anna Vlaskina
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
| | - Raif Vasilov
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
| | - Vladimir I. Timofeev
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
- Federal Scientific Research Center “Crystallography and Photonics”, RAS, Moscow, Russian Federation
| | - Tatiana V. Rakitina
- Kurchatov Complex of NBICS-Technologies, National Research Center «Kurchatov Institute», Moscow, Russian Federation
- Shemyakin&Ovchinnikov Institute of Bioorganic Chemistry, RAS, Moscow, Russian Federation
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18
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Abstract
In bacteria, chromosomal DNA must be efficiently compacted to fit inside the small cell compartment while remaining available for the proteins involved in replication, segregation, and transcription. Among the nucleoid-associated proteins (NAPs) responsible for maintaining this highly organized and yet dynamic chromosome structure, the HU protein is one of the most conserved and highly abundant. HupB, a homologue of HU, was recently identified in mycobacteria. This intriguing mycobacterial NAP is composed of two domains: an N-terminal domain that resembles bacterial HU, and a long and distinctive C-terminal domain that contains several PAKK/KAAK motifs, which are characteristic of the H1/H5 family of eukaryotic histones. In this study, we analyzed the in vivo binding of HupB on the chromosome scale. By using PALM (photoactivated localization microscopy) and ChIP-Seq (chromatin immunoprecipitation followed by deep sequencing), we observed that the C-terminal domain is indispensable for the association of HupB with the nucleoid. Strikingly, the in vivo binding of HupB displayed a bias from the origin (oriC) to the terminus (ter) of the mycobacterial chromosome (numbers of binding sites decreased toward ter). We hypothesized that this binding mode reflects a role for HupB in organizing newly replicated oriC regions. Thus, HupB may be involved in coordinating replication with chromosome segregation.IMPORTANCE We currently know little about the organization of the mycobacterial chromosome and its dynamics during the cell cycle. Among the mycobacterial nucleoid-associated proteins (NAPs) responsible for chromosome organization and dynamics, HupB is one of the most intriguing. It contains a long and distinctive C-terminal domain that harbors several PAKK/KAAK motifs, which are characteristic of the eukaryotic histone H1/H5 proteins. The HupB protein is also known to be crucial for the survival of tubercle bacilli during infection. Here, we provide in vivo experimental evidence showing that the C-terminal domain of HupB is crucial for its DNA binding. Our results suggest that HupB may be involved in organizing newly replicated regions and could help coordinate chromosome replication with segregation. Given that tuberculosis (TB) remains a serious worldwide health problem (10.4 million new TB cases were diagnosed in 2015, according to WHO) and new multidrug-resistant Mycobacterium tuberculosis strains are continually emerging, further studies of the biological function of HupB are needed to determine if this protein could be a prospect for novel antimicrobial drug development.
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Abebe AH, Aranovich A, Fishov I. HU content and dynamics in Escherichia coli during the cell cycle and at different growth rates. FEMS Microbiol Lett 2017; 364:4157278. [PMID: 28961819 DOI: 10.1093/femsle/fnx195] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 09/11/2017] [Indexed: 11/12/2022] Open
Abstract
DNA-binding proteins play an important role in maintaining bacterial chromosome structure and functions. Heat-unstable (HU) histone-like protein is one of the most abundant of these proteins and participates in all major chromosome-related activities. Owing to its low sequence specificity, HU fusions with fluorescent proteins were used for general staining of the nucleoid, aiming to reveal its morphology and dynamics. We have exploited a single chromosomal copy of hupA-egfp fusion under the native promoter and used quantitative microscopy imaging to investigate the amount and dynamics of HUα in Escherichia coli cells. We found that in steady-state growing populations the cellular HUα content is proportional to the cell size, whereas its concentration is size independent. Single-cell live microscopy imaging confirmed that the amount of HUα exponentially increases during the cell cycle, but its concentration is maintained constant. This supports the existence of an auto-regulatory mechanism underlying the HUα cellular level, in addition to reflecting the gene copy number. Both the HUα amount and concentration strongly increase with the cell growth rate in different culture media. Unexpectedly, the HU/DNA stoichiometry also remarkably increases with the growth rate. This last finding may be attributed to a higher requirement for maintaining the chromosome structure in nucleoids with higher complexity.
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Affiliation(s)
- Anteneh Hailu Abebe
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 8410501, Israel.,Medical Biotechnology Unit, Institute of Biotechnology, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
| | - Alexander Aranovich
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 8410501, Israel
| | - Itzhak Fishov
- Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653, Beer-Sheva 8410501, Israel
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Structural basis of the high thermal stability of the histone-like HU protein from the mollicute Spiroplasma melliferum KC3. Sci Rep 2016; 6:36366. [PMID: 27808161 PMCID: PMC5093408 DOI: 10.1038/srep36366] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 10/13/2016] [Indexed: 02/07/2023] Open
Abstract
The three-dimensional structure of the histone-like HU protein from the mycoplasma Spiroplasma melliferum KC3 (HUSpm) was determined at 1.4 Å resolution, and the thermal stability of the protein was evaluated by differential scanning calorimetry. A detailed analysis revealed that the three-dimensional structure of the HUSpm dimer is similar to that of its bacterial homologues but is characterized by stronger hydrophobic interactions at the dimer interface. This HUSpm dimer interface lacks salt bridges but is stabilized by a larger number of hydrogen bonds. According to the DSC data, HUSpm has a high denaturation temperature, comparable to that of HU proteins from thermophilic bacteria. To elucidate the structural basis of HUSpm thermal stability, we identified amino acid residues potentially responsible for this property and modified them by site-directed mutagenesis. A comparative analysis of the melting curves of mutant and wild-type HUSpm revealed the motifs that play a key role in protein thermal stability: non-conserved phenylalanine residues in the hydrophobic core, an additional hydrophobic loop at the N-terminal region of the protein, the absence of the internal cavity present at the dimer interface of some HU proteins, and the presence of additional hydrogen bonds between the monomers that are missing in homologous proteins.
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21
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Hammel M, Amlanjyoti D, Reyes FE, Chen JH, Parpana R, Tang HYH, Larabell CA, Tainer JA, Adhya S. HU multimerization shift controls nucleoid compaction. SCIENCE ADVANCES 2016; 2:e1600650. [PMID: 27482541 PMCID: PMC4966879 DOI: 10.1126/sciadv.1600650] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 06/14/2016] [Indexed: 05/05/2023]
Abstract
Molecular mechanisms controlling functional bacterial chromosome (nucleoid) compaction and organization are surprisingly enigmatic but partly depend on conserved, histone-like proteins HUαα and HUαβ and their interactions that span the nanoscale and mesoscale from protein-DNA complexes to the bacterial chromosome and nucleoid structure. We determined the crystal structures of these chromosome-associated proteins in complex with native duplex DNA. Distinct DNA binding modes of HUαα and HUαβ elucidate fundamental features of bacterial chromosome packing that regulate gene transcription. By combining crystal structures with solution x-ray scattering results, we determined architectures of HU-DNA nucleoproteins in solution under near-physiological conditions. These macromolecular conformations and interactions result in contraction at the cellular level based on in vivo imaging of native unlabeled nucleoid by soft x-ray tomography upon HUβ and ectopic HUα38 expression. Structural characterization of charge-altered HUαα-DNA complexes reveals an HU molecular switch that is suitable for condensing nucleoid and reprogramming noninvasive Escherichia coli into an invasive form. Collective findings suggest that shifts between networking and cooperative and noncooperative DNA-dependent HU multimerization control DNA compaction and supercoiling independently of cellular topoisomerase activity. By integrating x-ray crystal structures, x-ray scattering, mutational tests, and x-ray imaging that span from protein-DNA complexes to the bacterial chromosome and nucleoid structure, we show that defined dynamic HU interaction networks can promote nucleoid reorganization and transcriptional regulation as efficient general microbial mechanisms to help synchronize genetic responses to cell cycle, changing environments, and pathogenesis.
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Affiliation(s)
- Michal Hammel
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Corresponding author. (M.H.); (J.A.T.)
| | - Dhar Amlanjyoti
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Francis E. Reyes
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jian-Hua Chen
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94143, USA
| | - Rochelle Parpana
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Henry Y. H. Tang
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Carolyn A. Larabell
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Anatomy, University of California San Francisco, San Francisco, CA 94143, USA
| | - John A. Tainer
- Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
- Corresponding author. (M.H.); (J.A.T.)
| | - Sankar Adhya
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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22
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Tan C, Terakawa T, Takada S. Dynamic Coupling among Protein Binding, Sliding, and DNA Bending Revealed by Molecular Dynamics. J Am Chem Soc 2016; 138:8512-22. [DOI: 10.1021/jacs.6b03729] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Cheng Tan
- Department
of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Tsuyoshi Terakawa
- Department
of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032, United States
| | - Shoji Takada
- Department
of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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23
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HU histone-like DNA-binding protein from Thermus thermophilus: structural and evolutionary analyses. Extremophiles 2016; 20:695-709. [DOI: 10.1007/s00792-016-0859-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 06/14/2016] [Indexed: 10/21/2022]
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O’Neil P, Lovell S, Mehzabeen N, Battaile K, Biswas I. Crystal structure of histone-like protein from Streptococcus mutans refined to 1.9 Å resolution. Acta Crystallogr F Struct Biol Commun 2016; 72:257-62. [PMID: 27050257 PMCID: PMC4822980 DOI: 10.1107/s2053230x1600217x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/04/2016] [Indexed: 12/18/2022] Open
Abstract
Nucleoid-associated proteins (NAPs) in prokaryotes play an important architectural role in DNA bending, supercoiling and DNA compaction. In addition to architectural roles, some NAPs also play regulatory roles in DNA replication and repair, and act as global transcriptional regulators in many bacteria. Bacteria encode multiple NAPs and some of them are even essential for survival. Streptococcus mutans, a dental pathogen, encodes one such essential NAP called histone-like protein (HLP). Here, the three-dimensional structure of S. mutans HLP has been determined to 1.9 Å resolution. The HLP structure is a dimer and shares a high degree of similarity with other bacterial NAPs, including HU. Since HLPs are essential for the survival of pathogenic streptococci, this structure determination is potentially beneficial for future drug development against these pathogens.
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Affiliation(s)
- Pierce O’Neil
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Scott Lovell
- Protein Structure Laboratory, Del Shankel Structural Biology Center, University of Kansas, Kansas City, KS 66047, USA
| | - Nurjahan Mehzabeen
- Protein Structure Laboratory, Del Shankel Structural Biology Center, University of Kansas, Kansas City, KS 66047, USA
| | - Kevin Battaile
- IMCA-CAT, Hauptman–Woodward Medical Research Institute, APS, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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Abstract
This review provides a brief review of the current understanding of the structure-function relationship of the Escherichia coli nucleoid developed after the overview by Pettijohn focusing on the physical properties of nucleoids. Isolation of nucleoids requires suppression of DNA expansion by various procedures. The ability to control the expansion of nucleoids in vitro has led to purification of nucleoids for chemical and physical analyses and for high-resolution imaging. Isolated E. coli genomes display a number of individually intertwined supercoiled loops emanating from a central core. Metabolic processes of the DNA double helix lead to three types of topological constraints that all cells must resolve to survive: linking number, catenates, and knots. The major species of nucleoid core protein share functional properties with eukaryotic histones forming chromatin; even the structures are different from histones. Eukaryotic histones play dynamic roles in the remodeling of eukaryotic chromatin, thereby controlling the access of RNA polymerase and transcription factors to promoters. The E. coli genome is tightly packed into the nucleoid, but, at each cell division, the genome must be faithfully replicated, divided, and segregated. Nucleoid activities such as transcription, replication, recombination, and repair are all affected by the structural properties and the special conformations of nucleoid. While it is apparent that much has been learned about the nucleoid, it is also evident that the fundamental interactions organizing the structure of DNA in the nucleoid still need to be clearly defined.
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Le Meur R, Loth K, Culard F, Castaing B, Landon C. Backbone assignment of the three dimers of HU from Escherichia coli at 293 K: EcHUα2, EcHUβ2 and EcHUαβ. BIOMOLECULAR NMR ASSIGNMENTS 2015; 9:359-363. [PMID: 25924603 DOI: 10.1007/s12104-015-9610-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/27/2015] [Indexed: 06/04/2023]
Abstract
HU is one of the major nucleoid-associated proteins involved in bacterial chromosome structure and in all DNA-dependent cellular activities. Similarly to eukaryotic histones, this small dimeric basic protein wraps DNA in a non-sequence specific manner, promoting DNA super-structures. In most bacteria, HU is a homodimeric protein encoded by a single gene. However, in enterobacteria such as Escherichia coli, the presence of two genes coding for two peptidic chains, HUα and HUβ, lead to the coexistence of three forms: two homodimers EcHUα2 and EcHUβ2, as well as a heterodimer EcHUαβ. Genetic and biochemical investigation suggest that each EcHU dimer plays a specific physiological role in bacteria. Their relative abundance depends on the environmental conditions and is driven by an essential, yet unknown, fast outstanding chain-exchange mechanism at physiological temperature. Our goal is to understand this fundamental mechanism from a structural and kinetics standpoint using NMR. For this purpose, the first steps are the assignment of each dimer in their native and intermediate states. Here, we report the backbone assignment of each HU dimers from E. coli at 293 K in their native state.
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Affiliation(s)
- Rémy Le Meur
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique UPR 4301, Université d'Orléans, rue Charles Sadron, 45071, Orléans Cedex 2, France
| | - Karine Loth
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique UPR 4301, Université d'Orléans, rue Charles Sadron, 45071, Orléans Cedex 2, France.
| | - Françoise Culard
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique UPR 4301, Université d'Orléans, rue Charles Sadron, 45071, Orléans Cedex 2, France
| | - Bertrand Castaing
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique UPR 4301, Université d'Orléans, rue Charles Sadron, 45071, Orléans Cedex 2, France
| | - Céline Landon
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique UPR 4301, Université d'Orléans, rue Charles Sadron, 45071, Orléans Cedex 2, France
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The nucleoid-associated protein HU enhances 8-oxoguanine base excision by the formamidopyrimidine-DNA glycosylase. Biochem J 2015; 471:13-23. [DOI: 10.1042/bj20150387] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 07/10/2015] [Indexed: 11/17/2022]
Abstract
The major E. coli histone-like HU protein is identified as a strong stimulator of the DNA glycosylase Fpg by inducing enzyme product release. According to an active molecular process, HU acts as a molecular partner for an efficient DNA-repair process.
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Boyko K, Gorbacheva M, Rakitina T, Korzhenevskiy D, Vanyushkina A, Kamashev D, Lipkin A, Popov V. Expression, purification, crystallization and preliminary X-ray crystallographic analysis of the histone-like HU protein from Spiroplasma melliferum KC3. Acta Crystallogr F Struct Biol Commun 2015; 71:24-7. [PMID: 25615963 PMCID: PMC4304742 DOI: 10.1107/s2053230x14025333] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 11/18/2014] [Indexed: 11/10/2022] Open
Abstract
HU proteins belong to the nucleoid-associated proteins (NAPs) that are involved in vital processes such as DNA compaction and reparation, gene transcription etc. No data are available on the structures of HU proteins from mycoplasmas. To this end, the HU protein from the parasitic mycoplasma Spiroplasma melliferum KC3 was cloned, overexpressed in Escherichia coli and purified to homogeneity. Prismatic crystals of the protein were obtained by the vapour-diffusion technique at 4°C. The crystals diffracted to 1.36 Å resolution (the best resolution ever obtained for a HU protein). The diffraction data were indexed in space group C2 and the structure of the protein was solved by the molecular-replacement method with one monomer per asymmetric unit.
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Affiliation(s)
- Konstantin Boyko
- Laboratory of Enzyme Engineering, A. N. Bach Institute of Biochemistry, RAS, Leninsky Prospekt 33/2, Moscow 119071, Russian Federation
- The Protein Factory, NBICS Center, National Research Centre ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Marina Gorbacheva
- Laboratory of Enzyme Engineering, A. N. Bach Institute of Biochemistry, RAS, Leninsky Prospekt 33/2, Moscow 119071, Russian Federation
- The Protein Factory, NBICS Center, National Research Centre ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Tatiana Rakitina
- The Protein Factory, NBICS Center, National Research Centre ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
- Laboratory of Hormonal Regulation Proteins, Institute of Bioorganic Chemistry, RAS, Miklukho-Maklaya 16/10, Moscow 117997, Russian Federation
| | - Dmitry Korzhenevskiy
- The Protein Factory, NBICS Center, National Research Centre ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Anna Vanyushkina
- SRI of Physical-Chemical Medicine, Malaya Pirogovskaya 1a, Moscow 119435, Russian Federation
| | - Dmitry Kamashev
- SRI of Physical-Chemical Medicine, Malaya Pirogovskaya 1a, Moscow 119435, Russian Federation
| | - Alexey Lipkin
- The Protein Factory, NBICS Center, National Research Centre ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Vladimir Popov
- Laboratory of Enzyme Engineering, A. N. Bach Institute of Biochemistry, RAS, Leninsky Prospekt 33/2, Moscow 119071, Russian Federation
- The Protein Factory, NBICS Center, National Research Centre ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
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Kim J, Oliveros JC, Nikel PI, de Lorenzo V, Silva-Rocha R. Transcriptomic fingerprinting of Pseudomonas putida under alternative physiological regimes. ENVIRONMENTAL MICROBIOLOGY REPORTS 2013; 5:883-891. [PMID: 24249296 DOI: 10.1111/1758-2229.12090] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/22/2013] [Accepted: 07/22/2013] [Indexed: 06/02/2023]
Abstract
Pseudomonas putida KT2440 is a metabolically versatile soil bacterium useful both as a model biodegradative organism and as a host of catalytic activities of biotechnological interest. In this report, we present the high-resolution transcriptome of P. putida cultured on different carbon sources as revealed by deep sequencing of the corresponding RNA pools. Examination of the data from growth on substrates that are processed through distinct pathways (glucose, fructose, succinate and glycerol) revealed that ≥ 20% of the P. putida genome is differentially expressed depending on the ensuing physiological regime. Changes affected not only metabolic genes but also a suite of global regulators, e.g. the rpoS sigma subunit of RNA polymerase, various cold-shock proteins and the three HU histone-like proteins. Specifically, the genes encoding HU subunit variants hupA, hupB and hupN drastically altered their expression levels (and thus their ability to form heterodimeric combinations) under the diverse growth conditions. Furthermore, we found that two small RNAs, crcZ and crcY, known to inhibit the Crc protein that mediates catabolite repression in P. putida, were both down-regulated by glucose. The raw transcriptomic data generated in this work is made available to the community through the Gene Expression Omnibus database.
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Affiliation(s)
- Juhyun Kim
- Systems Biology Program, Centro Nacional de Biotecnología CSIC, Cantoblanco-Madrid, 28049, Spain
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30
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Doyle CM, Rumfeldt JA, Broom HR, Broom A, Stathopulos PB, Vassall KA, Almey JJ, Meiering EM. Energetics of oligomeric protein folding and association. Arch Biochem Biophys 2012; 531:44-64. [PMID: 23246784 DOI: 10.1016/j.abb.2012.12.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/29/2012] [Accepted: 12/05/2012] [Indexed: 12/11/2022]
Abstract
In nature, proteins most often exist as complexes, with many of these consisting of identical subunits. Understanding of the energetics governing the folding and misfolding of such homooligomeric proteins is central to understanding their function and misfunction, in disease or biotechnology. Much progress has been made in defining the mechanisms and thermodynamics of homooligomeric protein folding. In this review, we outline models as well as calorimetric and spectroscopic methods for characterizing oligomer folding, and describe extensive results obtained for diverse proteins, ranging from dimers to octamers and higher order aggregates. To our knowledge, this area has not been reviewed comprehensively in years, and the collective progress is impressive. The results provide evolutionary insights into the development of subunit interfaces, mechanisms of oligomer folding, and contributions of oligomerization to protein stability, function and regulation. Thermodynamic analyses have also proven valuable for understanding protein misfolding and aggregation mechanisms, suggesting new therapeutic avenues. Successful recent designs of novel, functional proteins demonstrate increased understanding of oligomer folding. Further rigorous analyses using multiple experimental and computational approaches are still required, however, to achieve consistent and accurate prediction of oligomer folding energetics. Modeling the energetics remains challenging but is a promising avenue for future advances.
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Affiliation(s)
- Colleen M Doyle
- Guelph-Waterloo Centre for Graduate Studies in Chemistry and Biochemistry, and Department of Chemistry, University of Waterloo, 200 University Ave. West, Waterloo, ON, Canada
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Sousounis K, Haney CE, Cao J, Sunchu B, Tsonis PA. Conservation of the three-dimensional structure in non-homologous or unrelated proteins. Hum Genomics 2012; 6:10. [PMID: 23244440 PMCID: PMC3500211 DOI: 10.1186/1479-7364-6-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 05/14/2012] [Indexed: 12/12/2022] Open
Abstract
In this review, we examine examples of conservation of protein structural motifs in unrelated or non-homologous proteins. For this, we have selected three DNA-binding motifs: the histone fold, the helix-turn-helix motif, and the zinc finger, as well as the globin-like fold. We show that indeed similar structures exist in unrelated proteins, strengthening the concept that three-dimensional conservation might be more important than the primary amino acid sequence.
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32
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Koh J, Shkel I, Saecker RM, Record MT. Nonspecific DNA binding and bending by HUαβ: interfaces of the three binding modes characterized by salt-dependent thermodynamics. J Mol Biol 2011; 410:241-67. [PMID: 21513716 DOI: 10.1016/j.jmb.2011.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 03/01/2011] [Accepted: 04/01/2011] [Indexed: 10/18/2022]
Abstract
Previous isothermal titration calorimetry (ITC) and Förster resonance energy transfer studies demonstrated that Escherichia coli HU(αβ) binds nonspecifically to duplex DNA in three different binding modes: a tighter-binding 34-bp mode that interacts with DNA in large (>34 bp) gaps between bound proteins, reversibly bending it by 140(o) and thereby increasing its flexibility, and two weaker, modestly cooperative small site-size modes (10 bp and 6 bp) that are useful for filling gaps between bound proteins shorter than 34 bp. Here we use ITC to determine the thermodynamics of these binding modes as a function of salt concentration, and we deduce that DNA in the 34-bp mode is bent around-but not wrapped on-the body of HU, in contrast to specific binding of integration host factor. Analyses of binding isotherms (8-bp, 15-bp, and 34-bp DNA) and initial binding heats (34-bp, 38-bp, and 160-bp DNA) reveal that all three modes have similar log-log salt concentration derivatives of the binding constants (Sk(i)) even though their binding site sizes differ greatly; the most probable values of Sk(i) on 34-bp DNA or larger DNA are -7.5±0.5. From the similarity of Sk(i) values, we conclude that the binding interfaces of all three modes involve the same region of the arms and saddle of HU. All modes are entropy-driven, as expected for nonspecific binding driven by the polyelectrolyte effect. The bent DNA 34-bp mode is most endothermic, presumably because of the cost of HU-induced DNA bending, while the 6-bp mode is modestly exothermic at all salt concentrations examined. Structural models consistent with the observed Sk(i) values are proposed.
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Affiliation(s)
- Junseock Koh
- Program in Biophysics, University of Wisconsin-Madison, Madison, WI 53706, USA.
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33
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Garnier N, Loth K, Coste F, Augustyniak R, Nadan V, Damblon C, Castaing B. An alternative flexible conformation of the E. coli HUβ2 protein: structural, dynamics, and functional aspects. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 40:117-29. [DOI: 10.1007/s00249-010-0630-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 09/15/2010] [Accepted: 09/20/2010] [Indexed: 11/29/2022]
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34
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Yadav SC, Jagannadham MV, Kundu S. Equilibrium unfolding of kinetically stable serine protease milin: the presence of various active and inactive dimeric intermediates. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2010; 39:1385-96. [DOI: 10.1007/s00249-010-0593-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 02/24/2010] [Accepted: 02/28/2010] [Indexed: 11/29/2022]
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35
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Liao JH, Lin YC, Hsu J, Lee AYL, Chen TA, Hsu CH, Chir JL, Hua KF, Wu TH, Hong LJ, Yen PW, Chiou A, Wu SH. Binding and cleavage of E. coli HUbeta by the E. coli Lon protease. Biophys J 2010; 98:129-37. [PMID: 20085725 DOI: 10.1016/j.bpj.2009.09.052] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 10/20/2022] Open
Abstract
The Escherichia coli Lon protease degrades the E. coli DNA-binding protein HUbeta, but not the related protein HUalpha. Here we show that the Lon protease binds to both HUbeta and HUalpha, but selectively degrades only HUbeta in the presence of ATP. Mass spectrometry of HUbeta peptide fragments revealed that region K18-G22 is the preferred cleavage site, followed in preference by L36-K37. The preferred cleavage site was further refined to A20-A21 by constructing and testing mutant proteins; Lon degraded HUbeta-A20Q and HUbeta-A20D more slowly than HUbeta. We used optical tweezers to measure the rupture force between HU proteins and Lon; HUalpha, HUbeta, and HUbeta-A20D can bind to Lon, and in the presence of ATP, the rupture force between each of these proteins and Lon became weaker. Our results support a mechanism of Lon protease cleavage of HU proteins in at least three stages: binding of Lon with the HU protein (HUbeta, HUalpha, or HUbeta-A20D); hydrolysis of ATP by Lon to provide energy to loosen the binding to the HU protein and to allow an induced-fit conformational change; and specific cleavage of only HUbeta.
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Affiliation(s)
- Jiahn-Haur Liao
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
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Suresh A, Karthikraja V, Lulu S, Kangueane U, Kangueane P. A decision tree model for the prediction of homodimer folding mechanism. Bioinformation 2009; 4:197-205. [PMID: 20461159 PMCID: PMC2859576 DOI: 10.6026/97320630004197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 11/09/2009] [Indexed: 11/25/2022] Open
Abstract
The formation of protein homodimer complexes for molecular catalysis and regulation is fascinating. The homodimer formation through 2S (2 state), 3SMI (3 state with monomer intermediate) and 3SDI (3 state with dimer intermediate) folding mechanism is known for 47 homodimer structures. Our dataset of forty-seven homodimers consists of twenty-eight 2S, twelve 3SMI and seven 3SDI. The dataset is characterized using monomer length, interface area and interface/total (I/T) residue ratio. It is found that 2S are often small in size with large I/T ratio and 3SDI are frequently large in size with small I/T ratio. Nonetheless, 3SMI have a mixture of these features. Hence, we used these parameters to develop a decision tree model. The decision tree model produced positive predictive values (PPV) of 72% for 2S, 58% for 3SMI and 57% for 3SDI in cross validation. Thus, the method finds application in assigning homodimers with folding mechanism.
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Affiliation(s)
- Abishek Suresh
- Biomedical Informatics, Pondicherry 607402
- AIMST University, Semeling 08100, Malaysia
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37
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Tarafdar PK, Vedantam LV, Kondreddy A, Podile AR, Swamy MJ. Biophysical investigations on the aggregation and thermal unfolding of harpinPss and identification of leucine-zipper-like motifs in harpins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1684-92. [DOI: 10.1016/j.bbapap.2009.07.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Revised: 07/11/2009] [Accepted: 07/31/2009] [Indexed: 11/17/2022]
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Surface-exposed histone-like protein a modulates adherence of Streptococcus gallolyticus to colon adenocarcinoma cells. Infect Immun 2009; 77:5519-27. [PMID: 19752027 DOI: 10.1128/iai.00384-09] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Streptococcus gallolyticus (formerly known as Streptococcus bovis biotype I) is a low-grade opportunistic pathogen which is considered to be associated with colon cancer. It is thought that colon polyps or tumors are the main portal of entry for this bacterium and that heparan sulfate proteoglycans (HSPGs) at the colon tumor cell surface are involved in bacterial adherence during the first stages of infection. In this study, we have shown that the histone-like protein A (HlpA) of S. gallolyticus is a genuine anchorless bacterial surface protein that binds to lipoteichoic acid (LTA) of the gram-positive cell wall in a growth phase-dependent manner. In addition, HlpA was shown to be one of the major heparin-binding proteins of S. gallolyticus able to bind to the HSPG-expressing colon tumor cell lines HCT116 and HT-29. Strikingly, although wild-type levels of HlpA appeared to contribute to adherence, coating of additional HlpA at the bacterial surface resulted in reduced binding to colon tumor cells. This may be explained by the fact that heparan sulfate and LTA compete for the same binding site in HlpA. Altogether, this study implies that HlpA serves as a fine-tuning factor for bacterial adherence.
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Oberto J, Nabti S, Jooste V, Mignot H, Rouviere-Yaniv J. The HU regulon is composed of genes responding to anaerobiosis, acid stress, high osmolarity and SOS induction. PLoS One 2009; 4:e4367. [PMID: 19194530 PMCID: PMC2634741 DOI: 10.1371/journal.pone.0004367] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 12/17/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The Escherichia coli heterodimeric HU protein is a small DNA-bending protein associated with the bacterial nucleoid. It can introduce negative supercoils into closed circular DNA in the presence of topoisomerase I. Cells lacking HU grow very poorly and display many phenotypes. METHODOLOGY/PRINCIPAL FINDINGS We analyzed the transcription profile of every Escherichia coli gene in the absence of one or both HU subunits. This genome-wide in silico transcriptomic approach, performed in parallel with in vivo genetic experimentation, defined the HU regulon. This large regulon, which comprises 8% of the genome, is composed of four biologically relevant gene classes whose regulation responds to anaerobiosis, acid stress, high osmolarity, and SOS induction. CONCLUSIONS/SIGNIFICANCE The regulation a large number of genes encoding enzymes involved in energy metabolism and catabolism pathways by HU explains the highly pleiotropic phenotype of HU-deficient cells. The uniform chromosomal distribution of the many operons regulated by HU strongly suggests that the transcriptional and nucleoid architectural functions of HU constitute two aspects of a unique protein-DNA interaction mechanism.
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Affiliation(s)
- Jacques Oberto
- Laboratoire de Physiologie Bactérienne, CNRS, UPR 9073, Institut de Biologie Physico-chimique, Paris, France
- * E-mail: (JO); (JR-Y)
| | - Sabrina Nabti
- Laboratoire de Physiologie Bactérienne, CNRS, UPR 9073, Institut de Biologie Physico-chimique, Paris, France
| | - Valérie Jooste
- INSERM, UMR 866, Epidemiology and Biostatistics group, University of Dijon, Dijon, France
| | | | - Josette Rouviere-Yaniv
- Laboratoire de Physiologie Bactérienne, CNRS, UPR 9073, Institut de Biologie Physico-chimique, Paris, France
- * E-mail: (JO); (JR-Y)
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The stability of the archaeal HU histone-like DNA-binding protein from Thermoplasma volcanium. Extremophiles 2008; 13:1-10. [PMID: 18818867 DOI: 10.1007/s00792-008-0190-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2008] [Accepted: 09/01/2008] [Indexed: 10/21/2022]
Abstract
The complete genome analysis of the archaeon Thermoplasma volcanium has revealed a gene assigned to encode the histone-like DNA-binding protein HU. Thermoplasma volcanium is a moderate thermophile growing around 60 degrees C and it is adaptable to aerobic and anaerobic environment and therefore it is unique as a candidate for the origin of eukaryotic nuclei in the endosymbiosis hypothesis. The HU protein is the major component of the bacterial nuclei and therefore it is an important protein to be studied. The gene for HUTvo protein (huptvo) was cloned from the genomic DNA of T. volcanium and overexpressed in Escherichia coli. A fast and efficient purification scheme was established to produce an adequate amount of bioactive protein for biochemical and biophysical studies. Highly purified HUTvo was studied for its DNA-binding activity and thermostability. As studied by circular dichroism and high-precision differential scanning microcalorimetry, the thermal unfolding of HUTvo protein is reversible and can be well described by a two-state model with dissociation of the native dimeric state into denatured monomers. The G versus T profile for HUTvo compared to the hyperthermophilic marine eubacterial counterpart from Thermotoga maritima, HUTmar, clearly shows that the archaeal protein has adopted a less efficient molecular mechanism to cope with high temperature. The molecular basis of this phenomenon is discussed.
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Koh J, Saecker RM, Record MT. DNA binding mode transitions of Escherichia coli HU(alphabeta): evidence for formation of a bent DNA--protein complex on intact, linear duplex DNA. J Mol Biol 2008; 383:324-46. [PMID: 18657548 DOI: 10.1016/j.jmb.2008.07.024] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 07/07/2008] [Accepted: 07/08/2008] [Indexed: 10/21/2022]
Abstract
Escherichia coli HU(alphabeta), a major nucleoid-associated protein, organizes chromosomal DNA and facilitates numerous DNA transactions. Using isothermal titration calorimetry, fluorescence resonance energy transfer and a series of DNA lengths (8 bp, 15 bp, 34 bp, 38 bp and 160 bp) we established that HU(alphabeta) interacts with duplex DNA using three different nonspecific binding modes. Both the HU to DNA molar ratio ([HU]/[DNA]) and DNA length dictate the dominant HU binding mode. On sufficiently long DNA (> or =34 bp), at low [HU]/[DNA], HU populates a noncooperative 34 bp binding mode with a binding constant of 2.1+/-0.4x10(6) M(-1), and a binding enthalpy of +7.7+/-0.6 kcal/mol at 15 degrees C and 0.15 M Na(+). With increasing [HU]/[DNA], HU bound in the noncooperative 34 bp mode progressively converts to two cooperative (omega approximately 20) modes with site sizes of 10 bp and 6 bp. These latter modes exhibit smaller binding constants (1.1+/-0.2x10(5) M(-1) for the 10 bp mode, 3.5+/-1.4x10(4) M(-1) for the 6 bp mode) and binding enthalpies (4.2+/-0.3 kcal/mol for the 10 bp mode, -1.6+/-0.3 kcal/mol for the 6 bp mode). As DNA length increases to 34 bp or more at low [HU]/[DNA], the small modes are replaced by the 34 bp binding mode. Fluorescence resonance energy transfer data demonstrate that the 34 bp mode bends DNA by 143+/-6 degrees whereas the 6 bp and 10 bp modes do not. The model proposed in this study provides a novel quantitative and comprehensive framework for reconciling previous structural and solution studies of HU, including single molecule (force extension measurement), fluorescence, and electrophoretic gel mobility-shift assays. In particular, it explains how HU condenses or extends DNA depending on the relative concentrations of HU and DNA.
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Affiliation(s)
- Junseock Koh
- Program in Biophysics, University of Wisconsin, Madison WI 53706, USA
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Deu E, Kirsch JF. The unfolding pathway for Apo Escherichia coli aspartate aminotransferase is dependent on the choice of denaturant. Biochemistry 2007; 46:5810-8. [PMID: 17425331 DOI: 10.1021/bi602621t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The guanidine hydrochloride (GdnHCl) mediated denaturation pathway for the apo form of homodimeric Escherichia coli aspartate aminotransferase (eAATase) (molecular mass = 43.5 kDa/monomer) includes a partially folded monomeric intermediate, M* [Herold, M., and Kirschner, K. (1990) Biochemistry 29, 1907-1913; Birolo, L., Dal Piaz, F., Pucci, P., and Marino, G. (2002) J. Biol. Chem. 277, 17428-17437]. The present investigation of the urea-mediated denaturation of eAATase finds no evidence for an M* species but uncovers a partially denatured dimeric form, D*, that is unpopulated in GdnHCl. Thus, the unfolding process is a function of the employed denaturant. D* retains less than 50% of the native secondary structure (circular dichroism), conserves significant quaternary and tertiary interactions, and unfolds cooperatively (mD*<==>U = 3.4 +/- 0.3 kcal mol-1 M-1). Therefore, the following equilibria obtain in the denaturation of apo-eAATase: D <==> 2M 2M* <==> 2U in GdnHCl and D <==> D* <==> 2U in urea (D = native dimer, M = folded monomer, and U = unfolded state). The free energy of unfolding of apo-eAATase (D <==> 2U) is 36 +/- 3 kcal mol-1, while that for the D* 2U transition is 24 +/- 2 kcal mol-1, both at 1 M standard state and pH 7.5.
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Affiliation(s)
- Edgar Deu
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3206, USA
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Guo F, Adhya S. Spiral structure of Escherichia coli HUalphabeta provides foundation for DNA supercoiling. Proc Natl Acad Sci U S A 2007; 104:4309-14. [PMID: 17360520 PMCID: PMC1838598 DOI: 10.1073/pnas.0611686104] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Indexed: 11/18/2022] Open
Abstract
We determined the crystal structure of the Escherichia coli nucleoid-associated HUalphabeta protein by x-ray diffraction and observed that the heterodimers form multimers with octameric units in three potential arrangements, which may serve specialized roles in different DNA transaction reactions. It is of special importance that one of the structures forms spiral filaments with left-handed rotations. A negatively superhelical DNA can be modeled to wrap around this left-handed HUalphabeta multimer. Whereas the wild-type HU generated negative DNA supercoiling in vitro, an engineered heterodimer with an altered amino acid residue critical for the formation of the left-handed spiral protein in the crystal was defective in the process, thus providing the structural explanation for the classical property of HU to restrain negative supercoils in DNA.
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Affiliation(s)
- Fusheng Guo
- Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD 20892-4264
| | - Sankar Adhya
- Laboratory of Molecular Biology, National Cancer Institute, Bethesda, MD 20892-4264
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45
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Ke H, Zhang S, Li J, Howlett GJ, Wang CC. Folding of Escherichia coli DsbC: characterization of a monomeric folding intermediate. Biochemistry 2007; 45:15100-10. [PMID: 17154548 DOI: 10.1021/bi061511m] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The homodimeric protein DsbC is a disulfide isomerase and a chaperone located in the periplasm of Escherichia coli. We have studied the guanidine hydrochloride (GdnHCl)-induced unfolding and refolding of DsbC using mutagenesis, intrinsic fluorescence, circular dichroism spectra, size-exclusion chromatography, and sedimentation velocity analysis. The equilibrium refolding and unfolding of DsbC was thermodynamically reversible. The equilibrium folding profile measured by fluorescence excited at 280 nm exhibited a three-state transition profile with a stable folding intermediate formed at 0-2.0 M GdnHCl followed by a second transition at higher GdnHCl concentrations. Sedimentation velocity data revealed dissociation of the dimer to the monomer over the concentration range of the first transition (0-2.0 M). In contrast, fluorescence emission data for DsbC excited at 295 nm showed a single two-state transition. Fluorescence emission data for the equilibrium unfolding of the monomeric G49R mutant, excited at either 295 or 280 nm, indicated a single two-state transition. Data obtained for the dimeric Y52W mutant indicated a strong protein concentration dependence of the first transition but no dependence of the second transition in equilibrium unfolding. This suggests that the fluorescence of Y52W sensitively reports conformational changes caused by dissociation of the dimer. Thus, the folding of DsbC follows a three-state transition model with a monomeric folding intermediate formed in 0-2.0 M GdnHCl. The folding of DsbC in the presence of DTT indicates an important role for the non-active site disulfide bond in stabilizing the conformation of the molecule. Dimerization ensures the performance of chaperone and isomerase functions of DsbC.
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Affiliation(s)
- Huimin Ke
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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46
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Manes NP, Gustin JK, Rue J, Mottaz HM, Purvine SO, Norbeck AD, Monroe ME, Zimmer JSD, Metz TO, Adkins JN, Smith RD, Heffron F. Targeted protein degradation by Salmonella under phagosome-mimicking culture conditions investigated using comparative peptidomics. Mol Cell Proteomics 2007; 6:717-27. [PMID: 17228056 DOI: 10.1074/mcp.m600282-mcp200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The pathogen Salmonella enterica is known to cause both food poisoning and typhoid fever. Because of the emergence of antibiotic-resistant isolates and the threat of bioterrorism (e.g. contamination of the food supply), there is a growing need to study this bacterium. In this investigation, comparative peptidomics was used to study S. enterica serovar Typhimurium cultured in either a rich medium or in an acidic, low magnesium, and minimal nutrient medium designed to roughly mimic the macrophage phagosomal environment (within which Salmonella are known to survive). Native peptides from cleared cell lysates were enriched by using isopropanol extraction and analyzed by using both LC-MS/MS and LC-FTICR-MS. We identified and quantified 5,163 peptides originating from 682 proteins, and the data clearly indicated that compared with Salmonella cultured in the rich medium, cells cultured in the phagosome-mimicking medium had dramatically higher abundances of a wide variety of protein degradation products, especially from ribosomal proteins. Salmonella from the same cultures were also analyzed using traditional, bottom-up proteomic methods, and when the peptidomics and proteomics data were analyzed together, two clusters of proteins targeted for proteolysis were tentatively identified. Possible roles of targeted proteolysis by phagocytosed Salmonella are discussed.
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Affiliation(s)
- Nathan P Manes
- Fundamental Science Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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47
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Hurtado-Gómez E, Fernández-Ballester G, Nothaft H, Gómez J, Titgemeyer F, Neira JL. Biophysical characterization of the enzyme I of the Streptomyces coelicolor phosphoenolpyruvate:sugar phosphotransferase system. Biophys J 2006; 90:4592-604. [PMID: 16581832 PMCID: PMC1471863 DOI: 10.1529/biophysj.105.076935] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The first protein in the bacterial phosphoenolpyruvate (PEP):sugar phosphotransferase system is the homodimeric 60-kDa enzyme I (EI), which autophosphorylates in the presence of PEP and Mg2+. The conformational stability and structure of the EI from Streptomyces coelicolor, EI(sc), were explored in the absence and in the presence of its effectors by using several biophysical probes (namely, fluorescence, far-ultraviolet circular dichroism, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry) and computational approaches. The structure of EI(sc) was obtained by homology modeling of the isolated N- and C-terminal domains of other EI proteins. The experimental results indicate that at physiological pH, the dimeric EI(sc) had a well-folded structure; however, at low pH, EI(sc) showed a partially unfolded state with the features of a molten globule, as suggested by fluorescence, far-ultraviolet circular dichroism, FTIR, and 8-anilino-1-naphthalene-sulfonic acid binding. The thermal stability of EI(sc), in the absence of PEP and Mg2+, was maximal at pH 7. The presence of PEP and Mg2+ did not change substantially the secondary structure of the protein, as indicated by FTIR measurements. However, quenching experiments and proteolysis patterns suggest conformational changes in the presence of PEP; furthermore, the thermal stability of EI(sc) was modified depending on the effector added. Our approach suggests that thermodynamical analysis might reveal subtle conformational changes.
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48
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Li L, Gunasekaran K, Gan JGK, Zhanhua C, Shapshak P, Sakharkar MK, Kangueane P. Structural features differentiate the mechanisms between 2S (2 state) and 3S (3 state) folding homodimers. Bioinformation 2005; 1:42-9. [PMID: 17597851 PMCID: PMC1891634 DOI: 10.6026/97320630001042] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 08/28/2005] [Accepted: 09/02/2005] [Indexed: 11/23/2022] Open
Abstract
The formation of homodimer complexes for interface stability, catalysis and regulation is intriguing. The mechanisms of homodimer complexations are even more interesting. Some homodimers form without intermediates (two-state (2S)) and others through the formation of stable intermediates (three-state (3S)). Here, we analyze 41 homodimer (25 2S and 16 3S) structures determined by X-ray crystallography to estimate structural differences between them. The analysis suggests that a combination of structural properties such as monomer length, subunit interface area, ratio of interface to interior hydrophobicity can predominately distinguish 2S and 3S homodimers. These findings are useful in the prediction of homodimer folding and binding mechanisms using structural data.
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Affiliation(s)
- Lei Li
- School of Mechanical and Aerospace Engineering,
Nanyang Technological University, Singapore 639798
| | - Kannan Gunasekaran
- Basic Research Program, SAIC-Frederick, Inc., Laboratory of Experimental and
Computational Biology, National Cancer Institute, Frederick, MD 21702, USA
| | - Jacob Gah-Kok Gan
- School of Mechanical and Aerospace Engineering,
Nanyang Technological University, Singapore 639798
| | - Cui Zhanhua
- School of Mechanical and Aerospace Engineering,
Nanyang Technological University, Singapore 639798
| | - Paul Shapshak
- Dementia/HIV Laboratory, Elliot Building Room 2013, Department of Psychiatry
and Beh Sci, University of Miami Miller Medical School, 1800 NW 10th Avenue, Miami, Florida 33136
| | - Meena Kishore Sakharkar
- School of Mechanical and Aerospace Engineering,
Nanyang Technological University, Singapore 639798
| | - Pandjassarame Kangueane
- School of Mechanical and Aerospace Engineering,
Nanyang Technological University, Singapore 639798
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49
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Abstract
Why are there so many dimeric proteins and enzymes? While for heterodimers a functional explanation seems quite reasonable, the case of homodimers is more puzzling. The number of homodimers found in all living organisms is rapidly increasing. A thorough inspection of the structural data from the available literature and stability (measured from denaturation-renaturation experiments) allows one to suggest that homodimers can be divided into three main types according to their mass and the presence of a (relatively) stable monomeric intermediate in the folding-unfolding pathway. Among other explanations, we propose that an essential advantage for a protein being dimeric may be the proper and rapid assembly in the cellular milieu.
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Affiliation(s)
- Giampiero Mei
- Department of Experimental Medicine and Biochemical Sciences, University of Rome 'Tor Vergata', Rome, Italy.
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50
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Lee DW, Hong YH, Choe EA, Lee SJ, Kim SB, Lee HS, Oh JW, Shin HH, Pyun YR. A thermodynamic study of mesophilic, thermophilic, and hyperthermophilic L-arabinose isomerases: the effects of divalent metal ions on protein stability at elevated temperatures. FEBS Lett 2005; 579:1261-6. [PMID: 15710423 DOI: 10.1016/j.febslet.2005.01.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 11/18/2004] [Accepted: 01/09/2005] [Indexed: 01/15/2023]
Abstract
To gain insight into the structural stability of homologous homo-tetrameric l-arabinose isomerases (AI), we have examined the isothermal guanidine hydrochloride (GdnHCl)-induced unfolding of AIs from mesophilic Bacillus halodurans (BHAI), thermophilic Geobacillus stearothermophilus (GSAI), and hyperthermophilic Thermotoga maritima (TMAI) using circular dichroism spectroscopy. The GdnHCl-induced unfolding of the AIs can be well described by a two-state reaction between native tetramers and unfolded monomers, which directly confirms the validity of the linear extrapolation method to obtain the intrinsic stabilities of these proteins. The resulting unfolding free energy (DeltaGU) values of the AIs as a function of temperature were fit to the Gibbs-Helmholtz equation to determine their thermodynamic parameters based on a two-state mechanism. Compared with the stability curves of BHAI in the presence and absence of Mn2+, those of holo GSAI and TMAI were more broadened than those of the apo enzymes at all temperatures, indicating increased melting temperatures (Tm) due to decreased heat capacity (DeltaGp). Moreover, the extent of difference in DeltaCp between the apo and holo thermophilic AIs is larger than that of BHAI. From these studies, we suggest that the metal dependence of the thermophilic AIs, resulting in the reduced DeltaCp, may play a significant role in structural stability compared to their mesophilic analogues, and that the extent of metal dependence of AI stability seems to be highly correlated to oligomerization.
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Affiliation(s)
- Dong-Woo Lee
- Department of Biotechnology, Yonsei University, Seoul 120-749, Korea
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