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Dadinova LA, Petoukhov MV, Gordienko AM, Manuvera VA, Lazarev VN, Rakitina TV, Mozhaev AA, Peters GS, Shtykova EV. Nucleoid-Associated Proteins HU and IHF: Oligomerization in Solution and Hydrodynamic Properties. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:640-654. [PMID: 37331710 DOI: 10.1134/s0006297923050073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/10/2023] [Accepted: 03/23/2023] [Indexed: 06/20/2023]
Abstract
Structure and function of bacterial nucleoid is controlled by the nucleoid-associated proteins (NAP). In any phase of growth, various NAPs, acting sequentially, condense nucleoid and facilitate formation of its transcriptionally active structure. However, in the late stationary phase, only one of the NAPs, Dps protein, is strongly expressed, and DNA-protein crystals are formed that transform nucleoid into a static, transcriptionally inactive structure, effectively protected from the external influences. Discovery of crystal structures in living cells and association of this phenomenon with the bacterial resistance to antibiotics has aroused great interest in studying this phenomenon. The aim of this work is to obtain and compare structures of two related NAPs (HU and IHF), since they are the ones that accumulate in the cell at the late stationary stage of growth, which precedes formation of the protective DNA-Dps crystalline complex. For structural studies, two complementary methods were used in the work: small-angle X-ray scattering (SAXS) as the main method for studying structure of proteins in solution, and dynamic light scattering as a complementary one. To interpret the SAXS data, various approaches and computer programs were used (in particular, the evaluation of structural invariants, rigid body modeling and equilibrium mixture analysis in terms of the volume fractions of its components were applied), which made it possible to determine macromolecular characteristics and obtain reliable 3D structural models of various oligomeric forms of HU and IHF proteins with ~2 nm resolution typical for SAXS. It was shown that these proteins oligomerize in solution to varying degrees, and IHF is characterized by the presence of large oligomers consisting of initial dimers arranged in a chain. An analysis of the experimental and published data made it possible to hypothesize that just before the Dps expression, it is IHF that forms toroidal structures previously observed in vivo and prepares the platform for formation of DNA-Dps crystals. The results obtained are necessary for further investigation of the phenomenon of biocrystal formation in bacterial cells and finding ways to overcome resistance of various pathogens to external conditions.
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Affiliation(s)
- Liubov A Dadinova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, 119333, Russia
| | - Maxim V Petoukhov
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, 119333, Russia
| | - Alexander M Gordienko
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, 119333, Russia
| | - Valentin A Manuvera
- Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine, Federal Medical Biological Agency, Moscow, 119435, Russia
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Region, 141701, Russia
| | - Vassili N Lazarev
- Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine, Federal Medical Biological Agency, Moscow, 119435, Russia
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow Region, 141701, Russia
| | - Tatiana V Rakitina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
- National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Andrey A Mozhaev
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, 119333, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Georgy S Peters
- National Research Centre "Kurchatov Institute", Moscow, 123182, Russia
| | - Eleonora V Shtykova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre "Crystallography and Photonics", Russian Academy of Sciences, Moscow, 119333, Russia.
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2
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Baquero F, Martínez JL, Sánchez A, Fernández-de-Bobadilla MD, San-Millán A, Rodríguez-Beltrán J. Bacterial Subcellular Architecture, Structural Epistasis, and Antibiotic Resistance. BIOLOGY 2023; 12:biology12050640. [PMID: 37237454 DOI: 10.3390/biology12050640] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/08/2023] [Accepted: 04/20/2023] [Indexed: 05/28/2023]
Abstract
Epistasis refers to the way in which genetic interactions between some genetic loci affect phenotypes and fitness. In this study, we propose the concept of "structural epistasis" to emphasize the role of the variable physical interactions between molecules located in particular spaces inside the bacterial cell in the emergence of novel phenotypes. The architecture of the bacterial cell (typically Gram-negative), which consists of concentrical layers of membranes, particles, and molecules with differing configurations and densities (from the outer membrane to the nucleoid) determines and is in turn determined by the cell shape and size, depending on the growth phases, exposure to toxic conditions, stress responses, and the bacterial environment. Antibiotics change the bacterial cell's internal molecular topology, producing unexpected interactions among molecules. In contrast, changes in shape and size may alter antibiotic action. The mechanisms of antibiotic resistance (and their vectors, as mobile genetic elements) also influence molecular connectivity in the bacterial cell and can produce unexpected phenotypes, influencing the action of other antimicrobial agents.
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Affiliation(s)
- Fernando Baquero
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), 28034 Madrid, Spain
- CIBER en Epidemiología y Salud Pública (CIBERESP), 28034 Madrid, Spain
| | | | - Alvaro Sánchez
- Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
| | - Miguel D Fernández-de-Bobadilla
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), 28034 Madrid, Spain
- CIBER en Enfermedades Infecciosas (CIBERINFECT), 28034 Madrid, Spain
| | - Alvaro San-Millán
- Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
- CIBER en Enfermedades Infecciosas (CIBERINFECT), 28034 Madrid, Spain
| | - Jerónimo Rodríguez-Beltrán
- Department of Microbiology, Ramón y Cajal University Hospital, Ramón y Cajal Institute for Health Research (IRYCIS), 28034 Madrid, Spain
- CIBER en Enfermedades Infecciosas (CIBERINFECT), 28034 Madrid, Spain
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3
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Transformation characteristics of A-DNA in salt solution revealed through molecular dynamics simulations. Biophys Chem 2022; 288:106845. [DOI: 10.1016/j.bpc.2022.106845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/25/2022] [Accepted: 06/06/2022] [Indexed: 11/17/2022]
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4
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Kou SB, Zhou KL, Lin ZY, Lou YY, Wang BL, Shi JH, Liu YX. Investigation of binding characteristics of ritonavir with calf thymus DNA with the help of spectroscopic techniques and molecular simulation. J Biomol Struct Dyn 2022; 40:2908-2916. [PMID: 33164672 DOI: 10.1080/07391102.2020.1844057] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The binding behavior of ritonavir (RTV), a HIV/AIDS protease inhibitor, with ct-DNA was characterized through multiple testing technologies and theoretical calculation. The findings revealed that the RTV-DNA complex was formed through the noncovalent interaction mainly including conventional hydrogen bonds and carbon hydrogen bonds as well as hydrophobic interactions (pi-alkyl interactions). The stoichiometry and binding constant of the RTV-DNA complex were 1:1 and 1.87 × 103 M-1 at 298 K, respectively, indicating that RTV has moderate affinity with ct-DNA. The findings confirmed that RTV binds to the minor groove of DNA. The outcomes of CD experiments showed that the binding with RTV changed the conformation of DNA slightly. However, the conformation of RTV had obvious changes after binding to DNA, meaning that the flexibility of RTV molecule played an important role in stabilizing the RTV-DNA complex. Meanwhile, the results of DFT calculation revealed that the RTV and DNA interaction caused the changes in the frontier molecular orbitals, dipole moment and atomic charge distribution of RTV, altering the chemical properties of RTV when it bound to DNA. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Song-Bo Kou
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Kai-Li Zhou
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Zhen-Yi Lin
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Yan-Yue Lou
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Bao-Li Wang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Jie-Hua Shi
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Ying-Xin Liu
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
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5
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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: 22] [Impact Index Per Article: 7.3] [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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6
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Maruyama H, Prieto EI, Nambu T, Mashimo C, Kashiwagi K, Okinaga T, Atomi H, Takeyasu K. Different Proteins Mediate Step-Wise Chromosome Architectures in Thermoplasma acidophilum and Pyrobaculum calidifontis. Front Microbiol 2020; 11:1247. [PMID: 32655523 PMCID: PMC7325993 DOI: 10.3389/fmicb.2020.01247] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/15/2020] [Indexed: 12/15/2022] Open
Abstract
Archaeal species encode a variety of distinct lineage-specific chromosomal proteins. We have previously shown that in Thermococcus kodakarensis, histone, Alba, and TrmBL2 play distinct roles in chromosome organization. Although our understanding of individual archaeal chromosomal proteins has been advancing, how archaeal chromosomes are folded into higher-order structures and how they are regulated are largely unknown. Here, we investigated the primary and higher-order structures of archaeal chromosomes from different archaeal lineages. Atomic force microscopy of chromosome spreads out of Thermoplasma acidophilum and Pyrobaculum calidifontis cells revealed 10-nm fibers and 30–40-nm globular structures, suggesting the occurrence of higher-order chromosomal folding. Our results also indicated that chromosome compaction occurs toward the stationary phase. Micrococcal nuclease digestion indicated that fundamental structural units of the chromosome exist in T. acidophilum and T. kodakarensis but not in P. calidifontis or Sulfolobus solfataricus. In vitro reconstitution showed that, in T. acidophilum, the bacterial HU protein homolog HTa formed a 6-nm fiber by wrapping DNA, and that Alba was responsible for the formation of the 10-nm fiber by binding along the DNA without wrapping. Remarkably, Alba could form different higher-order complexes with histone or HTa on DNA in vitro. Mass spectrometry detected HTa and Rad50 in the T. acidophilum chromosome but not in other species. A putative transcriptional regulator of the AsnC/Lrp family (Pcal_1183) was detected on the P. calidifontis chromosome, but not on that of other species studied. Putative membrane-associated proteins were detected in the chromosomes of the three archaeal species studied, including T. acidophilum, P. calidifontis, and T. kodakarensis. Collectively, our data show that Archaea use different combinations of proteins to achieve chromosomal architecture and functional regulation.
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Affiliation(s)
- Hugo Maruyama
- Department of Bacteriology, Osaka Dental University, Hirakata, Japan
| | - Eloise I Prieto
- National Institute of Molecular Biology and Biotechnology, College of Science, University of the Philippines Diliman, Quezon City, Philippines
| | - Takayuki Nambu
- Department of Bacteriology, Osaka Dental University, Hirakata, Japan
| | - Chiho Mashimo
- Department of Bacteriology, Osaka Dental University, Hirakata, Japan
| | - Kosuke Kashiwagi
- Department of Fixed Prosthodontics, Osaka Dental University, Hirakata, Japan
| | - Toshinori Okinaga
- Department of Bacteriology, Osaka Dental University, Hirakata, Japan
| | - Haruyuki Atomi
- Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
| | - Kunio Takeyasu
- Graduate School of Biostudies, Kyoto University, Kyoto, Japan
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7
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Walker DM, Freddolino PL, Harshey RM. A Well-Mixed E. coli Genome: Widespread Contacts Revealed by Tracking Mu Transposition. Cell 2020; 180:703-716.e18. [PMID: 32059782 DOI: 10.1016/j.cell.2020.01.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 10/21/2019] [Accepted: 01/22/2020] [Indexed: 02/06/2023]
Abstract
The three-dimensional structures of chromosomes are increasingly being recognized as playing a major role in cellular regulatory states. The efficiency and promiscuity of phage Mu transposition was exploited to directly measure in vivo interactions between genomic loci in E. coli. Two global organizing principles have emerged: first, the chromosome is well-mixed and uncompartmentalized, with transpositions occurring freely between all measured loci; second, several gene families/regions show "clustering": strong three-dimensional co-localization regardless of linear genomic distance. The activities of the SMC/condensin protein MukB and nucleoid-compacting protein subunit HU-α are essential for the well-mixed state; HU-α is also needed for clustering of 6/7 ribosomal RNA-encoding loci. The data are explained by a model in which the chromosomal structure is driven by dynamic competition between DNA replication and chromosomal relaxation, providing a foundation for determining how region-specific properties contribute to both chromosomal structure and gene regulation.
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Affiliation(s)
- David M Walker
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Peter L Freddolino
- Department of Biological Chemistry and Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Rasika M Harshey
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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8
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Watching DNA Replication Inhibitors in Action: Exploiting Time-Lapse Microfluidic Microscopy as a Tool for Target-Drug Interaction Studies in Mycobacterium. Antimicrob Agents Chemother 2019; 63:AAC.00739-19. [PMID: 31383667 PMCID: PMC6761567 DOI: 10.1128/aac.00739-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 07/26/2019] [Indexed: 01/08/2023] Open
Abstract
Spreading resistance to antibiotics and the emergence of multidrug-resistant strains have become frequent in many bacterial species, including mycobacteria, which are the causative agents of severe diseases and which have profound impacts on global health. Here, we used a system of microfluidics, fluorescence microscopy, and target-tagged fluorescent reporter strains of Mycobacterium smegmatis to perform real-time monitoring of replisome and chromosome dynamics following the addition of replication-altering drugs (novobiocin, nalidixic acid, and griselimycin) at the single-cell level. We found that novobiocin stalled replication forks and caused relaxation of the nucleoid and that nalidixic acid triggered rapid replisome collapse and compaction of the nucleoid, while griselimycin caused replisome instability, with the subsequent overinitiation of chromosome replication and overrelaxation of the nucleoid. In addition to study target-drug interactions, our system also enabled us to observe how the tested antibiotics affected the physiology of mycobacterial cells (i.e., growth, chromosome segregation, etc.).
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9
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Establishment of a Protein Concentration Gradient in the Outer Membrane Requires Two Diffusion-Limiting Mechanisms. J Bacteriol 2019; 201:JB.00177-19. [PMID: 31209077 DOI: 10.1128/jb.00177-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 06/12/2019] [Indexed: 11/20/2022] Open
Abstract
OmpA-like proteins are involved in the stabilization of the outer membrane, resistance to osmotic stress, and pathogenesis. In Caulobacter crescentus, OmpA2 forms a physiologically relevant concentration gradient that forms by an uncharacterized mechanism, in which the gradient orientation depends on the position of the gene locus. This suggests that OmpA2 is synthesized and translocated to the periplasm close to the position of the gene and that the gradient forms by diffusion of the protein from this point. To further understand how the OmpA2 gradient is established, we determined the localization and mobility of the full protein and of its two structural domains. We show that OmpA2 does not diffuse and that both domains are required for gradient formation. The C-terminal domain binds tightly to the cell wall and the immobility of the full protein depends on the binding of this domain to the peptidoglycan; in contrast, the N-terminal membrane β-barrel diffuses slowly. Our results support a model in which once OmpA2 is translocated to the periplasm, the N-terminal membrane β-barrel is required for an initial fast restriction of diffusion until the position of the protein is stabilized by the binding of the C-terminal domain to the cell wall. The implications of these results on outer membrane protein diffusion and organization are discussed.IMPORTANCE Protein concentration gradients play a relevant role in the organization of the bacterial cell. The Caulobacter crescentus protein OmpA2 forms an outer membrane polar concentration gradient. To understand the molecular mechanism that determines the formation of this gradient, we characterized the mobility and localization of the full protein and of its two structural domains an integral outer membrane β-barrel and a periplasmic peptidoglycan binding domain. Each domain has a different role in the formation of the OmpA2 gradient, which occurs in two steps. We also show that the OmpA2 outer membrane β-barrel can diffuse, which is in contrast to what has been reported previously for several integral outer membrane proteins in Escherichia coli, suggesting a different organization of the outer membrane proteins.
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10
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Ahammed KS, Pal R, Chakraborty J, Kanungo A, Purnima PS, Dutta S. DNA Structural Alteration Leading to Antibacterial Properties of 6-Nitroquinoxaline Derivatives. J Med Chem 2019; 62:7840-7856. [PMID: 31390524 DOI: 10.1021/acs.jmedchem.9b00599] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Structural integrity of the bacterial genome plays an important role in bacterial survival. Cellular consequences of an intolerable amount of change in the DNA structure are not well understood in bacteria. Here we have stated that binding of synthetic 6-nitroquinoxaline derivatives with DNA led to change in its global structure, subsequently culminating with over-supercoiled form through in-path intermediates. This structural change results in induction of programmed cell death like physiological hallmarks, which is dependent on substitution driven structural modulation properties of the scaffold. A sublethal dose of a representative derivative, 3a, significantly inhibits DNA synthesis, produces fragmented nucleoids, and alters membrane architecture. We have also shown that exposure to the compound changes the native morphology of Staphylococcus aureus cells and significantly disrupts preformed biofilms. Thus, our study gives new insight into bacterial responses to local or global DNA structural changes induced by 6-nitroquinoxaline small molecules.
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Affiliation(s)
- Khondakar Sayef Ahammed
- Organic and Medicinal Chemistry Division , CSIR- Indian Institute of Chemical Biology 4 , Raja S.C.Mullick Road , Kolkata , 700032 West Bengal , India
| | - Ritesh Pal
- Organic and Medicinal Chemistry Division , CSIR- Indian Institute of Chemical Biology 4 , Raja S.C.Mullick Road , Kolkata , 700032 West Bengal , India.,Academy of Scientific and Innovative Research (AcSIR) , Kolkata , 700032 West Bengal , India
| | - Jeet Chakraborty
- Organic and Medicinal Chemistry Division , CSIR- Indian Institute of Chemical Biology 4 , Raja S.C.Mullick Road , Kolkata , 700032 West Bengal , India
| | - Ajay Kanungo
- Organic and Medicinal Chemistry Division , CSIR- Indian Institute of Chemical Biology 4 , Raja S.C.Mullick Road , Kolkata , 700032 West Bengal , India.,Academy of Scientific and Innovative Research (AcSIR) , Kolkata , 700032 West Bengal , India
| | - Polnati Sravani Purnima
- Organic and Medicinal Chemistry Division , CSIR- Indian Institute of Chemical Biology 4 , Raja S.C.Mullick Road , Kolkata , 700032 West Bengal , India
| | - Sanjay Dutta
- Organic and Medicinal Chemistry Division , CSIR- Indian Institute of Chemical Biology 4 , Raja S.C.Mullick Road , Kolkata , 700032 West Bengal , India.,Academy of Scientific and Innovative Research (AcSIR) , Kolkata , 700032 West Bengal , India
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11
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Rani P, Nagaraja V. Genome-wide mapping of Topoisomerase I activity sites reveal its role in chromosome segregation. Nucleic Acids Res 2019; 47:1416-1427. [PMID: 30566665 PMCID: PMC6379724 DOI: 10.1093/nar/gky1271] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 11/30/2018] [Accepted: 12/13/2018] [Indexed: 11/13/2022] Open
Abstract
DNA Topoisomerase I (TopoI) in eubacteria is the principle DNA relaxase, belonging to Type 1A group. The enzyme from Mycobacterium smegmatis is essential for cell survival and distinct from other eubacteria in having several unusual characteristics. To understand genome-wide TopoI engagements in vivo, functional sites were mapped by employing a poisonous variant of the enzyme and a newly discovered inhibitor, both of which arrest the enzyme activity after the first transestrification reaction, thereby leading to the accumulation of protein-DNA covalent complexes. The cleavage sites are subsets of TopoI binding sites, implying that TopoI recruitment does not necessarily lead to DNA cleavage in vivo. The cleavage protection conferred by nucleoid associated proteins in vitro suggest a similar possibility in vivo. Co-localization of binding and cleavage sites of the enzyme on transcription units, implying that both TopoI recruitment and function are associated with active transcription. Attenuation of the cleavage upon Rifampicin treatment confirms the close connection between transcription and TopoI action. Notably, TopoI is inactive upstream of the Transcription start site (TSS) and activated following transcription initiation. The binding of TopoI at the Ter region, and the DNA cleavage at the Ter indicates TopoI involvement in chromosome segregation, substantiated by its catenation and decatenation activities.
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Affiliation(s)
- Phoolwanti Rani
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India.,Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
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12
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Two-step chromosome segregation in the stalked budding bacterium Hyphomonas neptunium. Nat Commun 2019; 10:3290. [PMID: 31337764 PMCID: PMC6650430 DOI: 10.1038/s41467-019-11242-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 06/28/2019] [Indexed: 12/11/2022] Open
Abstract
Chromosome segregation typically occurs after replication has finished in eukaryotes but during replication in bacteria. Here, we show that the alphaproteobacterium Hyphomonas neptunium, which proliferates by bud formation at the tip of a stalk-like cellular extension, segregates its chromosomes in a unique two-step process. First, the two sister origin regions are targeted to opposite poles of the mother cell, driven by the ParABS partitioning system. Subsequently, once the bulk of chromosomal DNA has been replicated and the bud exceeds a certain threshold size, the cell initiates a second segregation step during which it transfers the stalk-proximal origin region through the stalk into the nascent bud compartment. Thus, while chromosome replication and segregation usually proceed concurrently in bacteria, the two processes are largely uncoupled in H. neptunium, reminiscent of eukaryotic mitosis. These results indicate that stalked budding bacteria have evolved specific mechanisms to adjust chromosome segregation to their unusual life cycle.
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13
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Krogh TJ, Møller-Jensen J, Kaleta C. Impact of Chromosomal Architecture on the Function and Evolution of Bacterial Genomes. Front Microbiol 2018; 9:2019. [PMID: 30210483 PMCID: PMC6119826 DOI: 10.3389/fmicb.2018.02019] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/09/2018] [Indexed: 12/14/2022] Open
Abstract
The bacterial nucleoid is highly condensed and forms compartment-like structures within the cell. Much attention has been devoted to investigating the dynamic topology and organization of the nucleoid. In contrast, the specific nucleoid organization, and the relationship between nucleoid structure and function is often neglected with regard to importance for adaption to changing environments and horizontal gene acquisition. In this review, we focus on the structure-function relationship in the bacterial nucleoid. We provide an overview of the fundamental properties that shape the chromosome as a structured yet dynamic macromolecule. These fundamental properties are then considered in the context of the living cell, with focus on how the informational flow affects the nucleoid structure, which in turn impacts on the genetic output. Subsequently, the dynamic living nucleoid will be discussed in the context of evolution. We will address how the acquisition of foreign DNA impacts nucleoid structure, and conversely, how nucleoid structure constrains the successful and sustainable chromosomal integration of novel DNA. Finally, we will discuss current challenges and directions of research in understanding the role of chromosomal architecture in bacterial survival and adaptation.
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Affiliation(s)
- Thøger J Krogh
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Jakob Møller-Jensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Christoph Kaleta
- Institute of Experimental Medicine, Christian-Albrechts-University Kiel, Kiel, Germany
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14
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Butcher D, Chapagain P, Leng F, Fernandez-Lima F. Differentiating Parallel and Antiparallel DNA Duplexes in the Gas Phase Using Trapped Ion Mobility Spectrometry. J Phys Chem B 2018; 122:6855-6861. [PMID: 29886735 DOI: 10.1021/acs.jpcb.7b12544] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Deoxyribonucleic acids can form a wide variety of structural motifs which differ greatly from the typical antiparallel duplex stabilized by Watson-Crick base pairing. Many of these structures are thought to occur in vivo and may have essential roles in the biology of the cell. Among these is the parallel-stranded duplex-a structural motif in which DNA strands associate in a head-to-head fashion with the 5' ends at the same end of the duplex-which is stabilized by reverse Watson-Crick base pairing. In this study, parallel- and antiparallel-stranded DNA duplexes formed from two different 12-mer oligonucleotides were studied using native electrospray ionization combined with trapped ion mobility spectrometry and mass spectrometry. The DNA duplex charge plays an important role in the gas-phase mobility profile, with a more compact form in negative mode than in positive mode (ΔΩ ≈ 100 Å2 between -4 and +4). Despite sequence mismatches, homo- and hetero-DNA duplexes were formed in solution and transfer to the gas phase, where a more compact structure was observed for the parallel compared to the antiparallel duplexes (ΔΩ ≈ 50 Å2), in good agreement with theoretical calculations. Theoretical studies suggest that a reduction (or compaction) along the helical axis of the parallel and antiparallel DNA duplexes is observed upon transfer to the gas phase.
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Danchin A, Sekowska A, Noria S. Functional Requirements in the Program and the Cell Chassis for Next-Generation Synthetic Biology. Synth Biol (Oxf) 2018. [DOI: 10.1002/9783527688104.ch5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Antoine Danchin
- Institute of Cardiometabolism and Nutrition; 47 boulevard de l'Hôpital Paris 75013 France
| | - Agnieszka Sekowska
- Institute of Cardiometabolism and Nutrition; 47 boulevard de l'Hôpital Paris 75013 France
| | - Stanislas Noria
- Fondation Fourmentin-Guilbert; 2 avenue du Pavé Neuf Noisy le Grand 93160 France
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16
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Modulation of Global Transcriptional Regulatory Networks as a Strategy for Increasing Kanamycin Resistance of the Translational Elongation Factor-G Mutants in Escherichia coli. G3-GENES GENOMES GENETICS 2017; 7:3955-3966. [PMID: 29046437 PMCID: PMC5714492 DOI: 10.1534/g3.117.300284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Evolve and resequence experiments have provided us a tool to understand bacterial adaptation to antibiotics. In our previous work, we used short-term evolution to isolate mutants resistant to the ribosome targeting antibiotic kanamycin, and reported that Escherichia coli develops low cost resistance to kanamycin via different point mutations in the translation Elongation Factor-G (EF-G). Furthermore, we had shown that the resistance of EF-G mutants could be increased by second site mutations in the genes rpoD/cpxA/topA/cyaA Mutations in three of these genes had been discovered in earlier screens for aminoglycoside resistance. In this work, we expand our understanding of these second site mutations, the goal being to understand how these mutations affect the activities of the mutated gene products to confer resistance. We show that the mutation in cpxA most likely results in an active Cpx stress response. Further evolution of an EF-G mutant in a higher concentration of kanamycin than what was used in our previous experiments identified the cpxA locus as a primary target for a significant increase in resistance. The mutation in cyaA results in a loss of catalytic activity and probably results in resistance via altered CRP function. Despite a reduction in cAMP levels, the CyaAN600Y mutant has a transcriptome indicative of increased CRP activity, pointing to an unknown role for CyaA and / or cAMP in gene expression. From the transcriptomes of double and single mutants, we describe the epistasis between the mutation in EF-G and these second site mutations. We show that the large scale transcriptomic changes in the topoisomerase I (FusAA608E-TopAS180L) mutant likely result from increased negative supercoiling in the cell. Finally, genes with known roles in aminoglycoside resistance were present among the misregulated genes in the mutants.
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17
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Abstract
Many essential processes in biology share a common fundamental step-establishing physical contact between distant segments of DNA. How fast this step is accomplished sets the "speed limit" for the larger-scale processes it enables, whether the process is antibody production by the immune system or tissue differentiation in a developing embryo. This naturally leads us to ask, How long does it take for DNA segments that are strung out over millions of base pairs along the chromatin fiber to find each other in the crowded cell? This question, fundamental to biology, can be recognized as the physics problem of the first-passage time, or the waiting time for the first encounter. Here, we review a number of approaches to revealing the physical principles by which cells solve, with astonishing efficiency, the first-passage problem for remote genomic interactions.
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Affiliation(s)
- Yaojun Zhang
- Department of Physics, University of California at San Diego, La Jolla, California 92093; .,Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544
| | - Olga K Dudko
- Department of Physics, University of California at San Diego, La Jolla, California 92093;
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18
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Ultrastructure of compacted DNA in cyanobacteria by high-voltage cryo-electron tomography. Sci Rep 2016; 6:34934. [PMID: 27731339 PMCID: PMC5059737 DOI: 10.1038/srep34934] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/20/2016] [Indexed: 01/15/2023] Open
Abstract
Some cyanobacteria exhibit compaction of DNA in synchrony with their circadian rhythms accompanying cell division. Since the structure is transient, it has not yet been described in detail. Here, we successfully visualize the ultrastructure of compacted DNA in the cyanobacterium Synechococcus elongatus PCC 7942 under rigorous synchronized cultivation by means of high-voltage cryo-electron tomography. In 3D reconstructions of rapidly frozen cells, the compacted DNA appears as an undulating rod resembling a eukaryotic condensed chromosome. The compacted DNA also includes many small and paired polyphosphate bodies (PPBs), some of which seem to maintain contact with DNA that appears to twist away from them, indicating that they may act as interactive suppliers and regulators of phosphate for DNA synthesis. These observations throw light on the duplication and segregation mechanisms of cyanobacterial DNA and point to an important role for PPBs.
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Su YH, Rohani A, Warren CA, Swami NS. Tracking Inhibitory Alterations during Interstrain Clostridium difficile Interactions by Monitoring Cell Envelope Capacitance. ACS Infect Dis 2016; 2:544-551. [PMID: 27547818 PMCID: PMC4985749 DOI: 10.1021/acsinfecdis.6b00050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Indexed: 01/05/2023]
Abstract
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Global threats arising
from the increasing use of antibiotics coupled
with the high recurrence rates of Clostridium difficile (C. difficile) infections (CDI) after standard
antibiotic treatments highlight the role of commensal probiotic microorganisms,
including nontoxigenic C. difficile (NTCD) strains
in preventing CDI due to highly toxigenic C. difficile (HTCD) strains. However, optimization of the inhibitory permutations
due to commensal interactions in the microbiota requires probes capable
of monitoring phenotypic alterations to C. difficile cells. Herein, by monitoring the field screening behavior of the C. difficile cell envelope with respect to cytoplasmic polarization,
we demonstrate that inhibition of the host-cell colonization ability
of HTCD due to the S-layer alterations occurring after its co-culture
with NTCD can be quantitatively tracked on the basis of the capacitance
of the cell envelope of co-cultured HTCD. Furthermore, it is shown
that effective inhibition requires the dynamic contact of HTCD cells
with freshly secreted extracellular factors from NTCD because contact
with the cell-free supernatant causes only mild inhibition. We envision
a rapid method for screening the inhibitory permutations to arrest C. difficile colonization by routinely probing alterations
in the HTCD dielectrophoretic frequency response due to variations
in the capacitance of its cell envelope.
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Affiliation(s)
- Yi-Hsuan Su
- Department of Electrical & Computer Engineering and ‡Infectious Diseases, School of Medicine, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Ali Rohani
- Department of Electrical & Computer Engineering and ‡Infectious Diseases, School of Medicine, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Cirle A. Warren
- Department of Electrical & Computer Engineering and ‡Infectious Diseases, School of Medicine, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Nathan S. Swami
- Department of Electrical & Computer Engineering and ‡Infectious Diseases, School of Medicine, University of Virginia, Charlottesville, Virginia 22904, United States
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20
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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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21
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Biological substrates: Green alternatives in trace elemental preconcentration and speciation analysis. Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2016.04.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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22
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Azim MAR, Iliopoulos CS, Rahman MS, Samiruzzaman M. A Simple, Fast, Filter-Based Algorithm for Approximate Circular Pattern Matching. IEEE Trans Nanobioscience 2016; 15:93-100. [PMID: 26992174 DOI: 10.1109/tnb.2016.2542062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper deals with the approximate version of the circular pattern matching (ACPM) problem, which appears as an interesting problem in many biological contexts. The circular pattern matching problem consists in finding all occurrences of the rotations of a pattern P of length m in a text T of length n. In ACPM, we consider occurrences with k -mismatches under the Hamming distance model. In this paper, we present a simple and fast filter-based algorithm to solve the ACPM problem. We compare our algorithm with the state of the art algorithms and the results are found to be excellent. In particular, our algorithm runs almost twice as fast than the state of the art. Much of the efficiency of our algorithm can be attributed to its filters that are effective but extremely simple and lightweight.
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23
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Tolstorukov MY, Virnik K, Zhurkin VB, Adhya S. Organization of DNA in a bacterial nucleoid. BMC Microbiol 2016; 16:22. [PMID: 26897370 PMCID: PMC4761138 DOI: 10.1186/s12866-016-0637-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 02/04/2016] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND It is unclear how DNA is packaged in a bacterial cell in the absence of nucleosomes. To investigate the initial level of DNA condensation in bacterial nucleoid we used in vivo DNA digestion coupled with high-throughput sequencing of the digestion-resistant fragments. To this end, we transformed E. coli cells with a plasmid expressing micrococcal nuclease. The nuclease expression was under the control of AraC repressor, which enabled us to perform an inducible digestion of bacterial nucleoid inside a living cell. RESULTS Analysis of the genomic localization of the digestion-resistant fragments revealed their non-random distribution. The patterns observed in the distribution of the sequenced fragments indicate the presence of short DNA segments protected from the enzyme digestion, possibly because of interaction with DNA-binding proteins. The average length of such digestion-resistant segments is about 50 bp and the characteristic repeat in their distribution is about 90 bp. The gene starts are depleted of the digestion-resistant fragments, suggesting that these genomic regions are more exposed than genomic sequences on average. Sequence analysis of the digestion-resistant segments showed that while the GC-content of such sequences is close to the genome-wide value, they are depleted of A-tracts as compared to the bulk genomic DNA or to the randomized sequence of the same nucleotide composition. CONCLUSIONS Our results suggest that DNA is packaged in the bacterial nucleoid in a non-random way that facilitates interaction of the DNA binding factors with regulatory regions of the genome.
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Affiliation(s)
- Michael Y Tolstorukov
- Department of Molecular Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 02114, USA.
| | - Konstantin Virnik
- Laboratory of Immunoregulation, Division of Viral Products, Office of Vaccines, Center for Biologics, FDA, Silver Spring, MD, 20993, USA.
| | - Victor B Zhurkin
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Sankar Adhya
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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24
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Pulkkinen O, Metzler R. Variance-corrected Michaelis-Menten equation predicts transient rates of single-enzyme reactions and response times in bacterial gene-regulation. Sci Rep 2015; 5:17820. [PMID: 26635080 PMCID: PMC4669464 DOI: 10.1038/srep17820] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 11/06/2015] [Indexed: 01/07/2023] Open
Abstract
Many chemical reactions in biological cells occur at very low concentrations of constituent molecules. Thus, transcriptional gene-regulation is often controlled by poorly expressed transcription-factors, such as E.coli lac repressor with few tens of copies. Here we study the effects of inherent concentration fluctuations of substrate-molecules on the seminal Michaelis-Menten scheme of biochemical reactions. We present a universal correction to the Michaelis-Menten equation for the reaction-rates. The relevance and validity of this correction for enzymatic reactions and intracellular gene-regulation is demonstrated. Our analytical theory and simulation results confirm that the proposed variance-corrected Michaelis-Menten equation predicts the rate of reactions with remarkable accuracy even in the presence of large non-equilibrium concentration fluctuations. The major advantage of our approach is that it involves only the mean and variance of the substrate-molecule concentration. Our theory is therefore accessible to experiments and not specific to the exact source of the concentration fluctuations.
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Affiliation(s)
- Otto Pulkkinen
- Department of Physics, Tampere University of Technology, FI-33101 Tampere, Finland
| | - Ralf Metzler
- Department of Physics, Tampere University of Technology, FI-33101 Tampere, Finland
- Institute for Physics & Astronomy, University of Potsdam, D-14476 Potsdam-Golm, Germany
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25
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SimpLiFiCPM: A Simple and Lightweight Filter-Based Algorithm for Circular Pattern Matching. Int J Genomics 2015; 2015:259320. [PMID: 26557649 PMCID: PMC4628665 DOI: 10.1155/2015/259320] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 03/21/2015] [Indexed: 11/17/2022] Open
Abstract
This paper deals with the circular pattern matching (CPM) problem, which
appears as an interesting problem in many biological contexts. CPM consists in finding all occurrences of the rotations of a pattern 𝒫 of length m in a text 𝒯 of length n. In this paper, we present SimpLiFiCPM (pronounced “Simplify CPM”), a simple and lightweight filter-based algorithm to solve the problem. We compare our algorithm with the state-of-the-art algorithms and the results are found to be excellent. Much of the speed of our algorithm comes from the fact that our filters are effective but extremely simple and
lightweight.
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26
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A Glimpse to Background and Characteristics of Major Molecular Biological Networks. BIOMED RESEARCH INTERNATIONAL 2015; 2015:540297. [PMID: 26491677 PMCID: PMC4605226 DOI: 10.1155/2015/540297] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 07/22/2015] [Accepted: 08/18/2015] [Indexed: 12/11/2022]
Abstract
Recently, biology has become a data intensive science because of huge data sets produced by high throughput molecular biological experiments in diverse areas including the fields of genomics, transcriptomics, proteomics, and metabolomics. These huge datasets have paved the way for system-level analysis of the processes and subprocesses of the cell. For system-level understanding, initially the elements of a system are connected based on their mutual relations and a network is formed. Among omics researchers, construction and analysis of biological networks have become highly popular. In this review, we briefly discuss both the biological background and topological properties of major types of omics networks to facilitate a comprehensive understanding and to conceptualize the foundation of network biology.
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27
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Schoborg T, Labrador M. Expanding the roles of chromatin insulators in nuclear architecture, chromatin organization and genome function. Cell Mol Life Sci 2014; 71:4089-113. [PMID: 25012699 PMCID: PMC11113341 DOI: 10.1007/s00018-014-1672-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 05/31/2014] [Accepted: 06/23/2014] [Indexed: 01/08/2023]
Abstract
Of the numerous classes of elements involved in modulating eukaryotic chromosome structure and function, chromatin insulators arguably remain the most poorly understood in their contribution to these processes in vivo. Indeed, our view of chromatin insulators has evolved dramatically since their chromatin boundary and enhancer blocking properties were elucidated roughly a quarter of a century ago as a result of recent genome-wide, high-throughput methods better suited to probing the role of these elements in their native genomic contexts. The overall theme that has emerged from these studies is that chromatin insulators function as general facilitators of higher-order chromatin loop structures that exert both physical and functional constraints on the genome. In this review, we summarize the result of recent work that supports this idea as well as a number of other studies linking these elements to a diverse array of nuclear processes, suggesting that chromatin insulators exert master control over genome organization and behavior.
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Affiliation(s)
- Todd Schoborg
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN 37996 USA
- Present Address: Laboratory of Molecular Machines and Tissue Architecture, Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, 50 South Dr Rm 2122, Bethesda, MD 20892 USA
| | - Mariano Labrador
- Department of Biochemistry, Cellular and Molecular Biology, The University of Tennessee, M407 Walters Life Sciences, 1414 Cumberland Avenue, Knoxville, TN 37996 USA
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28
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Wang H, Yehoshua S, Ali SS, Navarre WW, Milstein JN. A biomechanical mechanism for initiating DNA packaging. Nucleic Acids Res 2014; 42:11921-7. [PMID: 25274732 PMCID: PMC4231757 DOI: 10.1093/nar/gku896] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The bacterial chromosome is under varying levels of mechanical stress due to a high degree of crowding and dynamic protein–DNA interactions experienced within the nucleoid. DNA tension is difficult to measure in cells and its functional significance remains unclear although in vitro experiments have implicated a range of biomechanical phenomena. Using single-molecule tools, we have uncovered a novel protein–DNA interaction that responds to fluctuations in mechanical tension by condensing DNA. We combined tethered particle motion (TPM) and optical tweezers experiments to probe the effects of tension on DNA in the presence of the Hha/H-NS complex. The nucleoid structuring protein H-NS is a key regulator of DNA condensation and gene expression in enterobacteria and its activity in vivo is affected by the accessory factor Hha. We find that tension, induced by optical tweezers, causes the rapid compaction of DNA in the presence of the Hha/H-NS complex, but not in the presence of H-NS alone. Our results imply that H-NS requires Hha to condense bacterial DNA and that this condensation could be triggered by the level of mechanical tension experienced along different regions of the chromosome.
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Affiliation(s)
- Haowei Wang
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada
| | - Samuel Yehoshua
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
| | - Sabrina S Ali
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - William Wiley Navarre
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Joshua N Milstein
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada
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Ghosh S, Mallick B, Nagaraja V. Direct regulation of topoisomerase activity by a nucleoid-associated protein. Nucleic Acids Res 2014; 42:11156-65. [PMID: 25200077 PMCID: PMC4176182 DOI: 10.1093/nar/gku804] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The topological homeostasis of bacterial chromosomes is maintained by the balance between compaction and the topological organization of genomes. Two classes of proteins play major roles in chromosome organization: the nucleoid-associated proteins (NAPs) and topoisomerases. The NAPs bind DNA to compact the chromosome, whereas topoisomerases catalytically remove or introduce supercoils into the genome. We demonstrate that HU, a major NAP of Mycobacterium tuberculosis specifically stimulates the DNA relaxation ability of mycobacterial topoisomerase I (TopoI) at lower concentrations but interferes at higher concentrations. A direct physical interaction between M. tuberculosis HU (MtHU) and TopoI is necessary for enhancing enzyme activity both in vitro and in vivo. The interaction is between the amino terminal domain of MtHU and the carboxyl terminal domain of TopoI. Binding of MtHU did not affect the two catalytic trans-esterification steps but enhanced the DNA strand passage, requisite for the completion of DNA relaxation, a new mechanism for the regulation of topoisomerase activity. An interaction-deficient mutant of MtHU was compromised in enhancing the strand passage activity. The species-specific physical and functional cooperation between MtHU and TopoI may be the key to achieve the DNA relaxation levels needed to maintain the optimal superhelical density of mycobacterial genomes.
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Affiliation(s)
- Soumitra Ghosh
- Department of Microbiology and Cell biology, Indian Institute of Science, Bangalore 560012, India
| | - Bratati Mallick
- Department of Microbiology and Cell biology, Indian Institute of Science, Bangalore 560012, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell biology, Indian Institute of Science, Bangalore 560012, India Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
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30
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Junier I. Conserved patterns in bacterial genomes: a conundrum physically tailored by evolutionary tinkering. Comput Biol Chem 2014; 53 Pt A:125-33. [PMID: 25239779 DOI: 10.1016/j.compbiolchem.2014.08.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2014] [Indexed: 11/17/2022]
Abstract
The proper functioning of bacteria is encoded in their genome at multiple levels or scales, each of which is constrained by specific physical forces. At the smallest spatial scales, interatomic forces dictate the folding and function of proteins and nucleic acids. On longer length scales, stochastic forces emerging from the thermal jiggling of proteins and RNAs impose strong constraints on the organization of genes along chromosomes, more particularly in the context of the building of nucleoprotein complexes and the operational mode of regulatory agents. At the cellular level, transcription, replication and cell division activities generate forces that act on both the internal structure and cellular location of chromosomes. The overall result is a complex multi-scale organization of genomes that reflects the evolutionary tinkering of bacteria. The goal of this review is to highlight avenues for deciphering this complexity by focusing on patterns that are conserved among evolutionarily distant bacteria. To this end, I discuss three different organizational scales: the protein structures, the chromosomal organization of genes and the global structure of chromosomes.
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Affiliation(s)
- Ivan Junier
- Centre for Genomic Regulation (CRG), Dr. Aiguader 88, 08003 Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain.
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31
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Barton C, Iliopoulos CS, Pissis SP. Fast algorithms for approximate circular string matching. Algorithms Mol Biol 2014; 9:9. [PMID: 24656145 PMCID: PMC4234210 DOI: 10.1186/1748-7188-9-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 03/17/2014] [Indexed: 11/16/2022] Open
Abstract
Background Circular string matching is a problem which naturally arises in many biological contexts. It consists in finding all occurrences of the rotations of a pattern of length m in a text of length n. There exist optimal average-case algorithms for exact circular string matching. Approximate circular string matching is a rather undeveloped area. Results In this article, we present a suboptimal average-case algorithm for exact circular string matching requiring time O(n) . Based on our solution for the exact case, we present two fast average-case algorithms for approximate circular string matching with k-mismatches, under the Hamming distance model, requiring time O(n) for moderate values of k, that is k=O(m/logm) . We show how the same results can be easily obtained under the edit distance model. The presented algorithms are also implemented as library functions. Experimental results demonstrate that the functions provided in this library accelerate the computations by more than three orders of magnitude compared to a naïve approach. Conclusions We present two fast average-case algorithms for approximate circular string matching with k-mismatches; and show that they also perform very well in practice. The importance of our contribution is underlined by the fact that the provided functions may be seamlessly integrated into any biological pipeline. The source code of the library is freely available at http://www.inf.kcl.ac.uk/research/projects/asmf/.
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32
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Huang Y, Mrázek J. Assessing diversity of DNA structure-related sequence features in prokaryotic genomes. DNA Res 2014; 21:285-97. [PMID: 24408877 PMCID: PMC4060949 DOI: 10.1093/dnares/dst057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Prokaryotic genomes are diverse in terms of their nucleotide and oligonucleotide composition as well as presence of various sequence features that can affect physical properties of the DNA molecule. We present a survey of local sequence patterns which have a potential to promote non-canonical DNA conformations (i.e. different from standard B-DNA double helix) and interpret the results in terms of relationships with organisms' habitats, phylogenetic classifications, and other characteristics. Our present work differs from earlier similar surveys not only by investigating a wider range of sequence patterns in a large number of genomes but also by using a more realistic null model to assess significant deviations. Our results show that simple sequence repeats and Z-DNA-promoting patterns are generally suppressed in prokaryotic genomes, whereas palindromes and inverted repeats are over-represented. Representation of patterns that promote Z-DNA and intrinsic DNA curvature increases with increasing optimal growth temperature (OGT), and decreases with increasing oxygen requirement. Additionally, representations of close direct repeats, palindromes and inverted repeats exhibit clear negative trends with increasing OGT. The observed relationships with environmental characteristics, particularly OGT, suggest possible evolutionary scenarios of structural adaptation of DNA to particular environmental niches.
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Affiliation(s)
- Yongjie Huang
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Jan Mrázek
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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Halverson JD, Smrek J, Kremer K, Grosberg AY. From a melt of rings to chromosome territories: the role of topological constraints in genome folding. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:022601. [PMID: 24472896 DOI: 10.1088/0034-4885/77/2/022601] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We review pro and contra of the hypothesis that generic polymer properties of topological constraints are behind many aspects of chromatin folding in eukaryotic cells. For that purpose, we review, first, recent theoretical and computational findings in polymer physics related to concentrated, topologically simple (unknotted and unlinked) chains or a system of chains. Second, we review recent experimental discoveries related to genome folding. Understanding in these fields is far from complete, but we show how looking at them in parallel sheds new light on both.
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Affiliation(s)
- Jonathan D Halverson
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA
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Jin DJ, Cagliero C, Zhou YN. Role of RNA polymerase and transcription in the organization of the bacterial nucleoid. Chem Rev 2013; 113:8662-82. [PMID: 23941620 PMCID: PMC3830623 DOI: 10.1021/cr4001429] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ding Jun Jin
- Transcription Control Section, Gene Regulation and Chromosome Biology Laboratory National Cancer Institute, NIH, P.O. Box B, Frederick, MD 21702
| | - Cedric Cagliero
- Transcription Control Section, Gene Regulation and Chromosome Biology Laboratory National Cancer Institute, NIH, P.O. Box B, Frederick, MD 21702
| | - Yan Ning Zhou
- Transcription Control Section, Gene Regulation and Chromosome Biology Laboratory National Cancer Institute, NIH, P.O. Box B, Frederick, MD 21702
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35
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Feig M, Sugita Y. Reaching new levels of realism in modeling biological macromolecules in cellular environments. J Mol Graph Model 2013; 45:144-56. [PMID: 24036504 DOI: 10.1016/j.jmgm.2013.08.017] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/14/2013] [Accepted: 08/19/2013] [Indexed: 12/21/2022]
Abstract
An increasing number of studies are aimed at modeling cellular environments in a comprehensive and realistic fashion. A major challenge in these efforts is how to bridge spatial and temporal scales over many orders of magnitude. Furthermore, there are additional challenges in integrating different aspects ranging from questions about biomolecular stability in crowded environments to the description of reactive processes on cellular scales. In this review, recent studies with models of biomolecules in cellular environments at different levels of detail are discussed in terms of their strengths and weaknesses. In particular, atomistic models, implicit representations of cellular environments, coarse-grained and spheroidal models of biomolecules, as well as the inclusion of reactive processes via reaction-diffusion models are described. Furthermore, strategies for integrating the different models into a comprehensive description of cellular environments are discussed.
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Affiliation(s)
- Michael Feig
- Department of Biochemistry & Molecular Biology and Department of Chemistry, Michigan State University, 603 Wilson Road, BCH 218, East Lansing, MI 48824, United States; RIKEN Quantitative Biology Center, International Medical Device Alliance (IMDA) 6F, 1-6-5 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
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36
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Shechter N, Zaltzman L, Weiner A, Brumfeld V, Shimoni E, Fridmann-Sirkis Y, Minsky A. Stress-induced condensation of bacterial genomes results in re-pairing of sister chromosomes: implications for double strand DNA break repair. J Biol Chem 2013; 288:25659-25667. [PMID: 23884460 DOI: 10.1074/jbc.m113.473025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Genome condensation is increasingly recognized as a generic stress response in bacteria. To better understand the physiological implications of this response, we used fluorescent markers to locate specific sites on Escherichia coli chromosomes following exposure to cytotoxic stress. We find that stress-induced condensation proceeds through a nonrandom, zipper-like convergence of sister chromosomes, which is proposed to rely on the recently demonstrated intrinsic ability of identical double-stranded DNA molecules to specifically identify each other. We further show that this convergence culminates in spatial proximity of homologous sites throughout chromosome arms. We suggest that the resulting apposition of homologous sites can explain how repair of double strand DNA breaks might occur in a mechanism that is independent of the widely accepted yet physiologically improbable genome-wide search for homologous templates. We claim that by inducing genome condensation and orderly convergence of sister chromosomes, diverse stress conditions prime bacteria to effectively cope with severe DNA lesions such as double strand DNA breaks.
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Affiliation(s)
| | | | | | - Vlad Brumfeld
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eyal Shimoni
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
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37
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Wang HC, Wu ML, Ko TP, Wang AHJ. Neisseria conserved hypothetical protein DMP12 is a DNA mimic that binds to histone-like HU protein. Nucleic Acids Res 2013; 41:5127-38. [PMID: 23531546 PMCID: PMC3643605 DOI: 10.1093/nar/gkt201] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/04/2013] [Accepted: 03/04/2013] [Indexed: 12/16/2022] Open
Abstract
DNA mimic proteins are unique factors that control the DNA-binding activity of target proteins by directly occupying their DNA-binding sites. To date, only a few DNA mimic proteins have been reported and their functions analyzed. Here, we present evidence that the Neisseria conserved hypothetical protein DMP12 should be added to this list. Our gel filtration and analytical ultracentrifugation results showed that the DMP12 monomer interacts with the dimeric form of the bacterial histone-like protein HU. Subsequent structural analysis of DMP12 showed that the shape and electrostatic surface of the DMP12 monomer are similar to those of the straight portion of the bent HU-bound DNA and complementary to those of HU protein dimer. DMP12 also protects HU protein from limited digestion by trypsin and enhances the growth rate Escherichia coli. Functionally, HU proteins participate in bacterial nucleoid formation, as well as recombination, gene regulation and DNA replication. The interaction between DMP12 and HU protein might, therefore, play important roles in these DNA-related mechanisms.
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Affiliation(s)
- Hao-Ching Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan, and Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Mao-Lun Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan, and Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan, and Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Andrew H.-J. Wang
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan, Core Facilities for Protein Structural Analysis, Academia Sinica, Taipei 115, Taiwan, and Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
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Priyadarshini R, Cugini C, Arndt A, Chen T, Tjokro NO, Goodman SD, Davey ME. The nucleoid-associated protein HUβ affects global gene expression in Porphyromonas gingivalis. MICROBIOLOGY-SGM 2012; 159:219-229. [PMID: 23175503 DOI: 10.1099/mic.0.061002-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
HU is a non-sequence-specific DNA-binding protein and one of the most abundant nucleoid-associated proteins in the bacterial cell. Like Escherichia coli, the genome of Porphyromonas gingivalis is predicted to encode both the HUα (PG1258) and the HUβ (PG0121) subunit. We have previously reported that PG0121 encodes a non-specific DNA-binding protein and that PG0121 is co-transcribed with the K-antigen capsule synthesis operon. We also reported that deletion of PG0121 resulted in downregulation of capsule operon expression and produced a P. gingivalis strain that is phenotypically deficient in surface polysaccharide production. Here, we show through complementation experiments in an E. coli MG1655 hupAB double mutant strain that PG0121 encodes a functional HU homologue. Microarray and quantitative RT-PCR analysis were used to further investigate global transcriptional regulation by HUβ using comparative expression profiling of the PG0121 (HUβ) mutant strain to the parent strain, W83. Our analysis determined that expression of genes encoding proteins involved in a variety of biological functions, including iron acquisition, cell division and translation, as well as a number of predicted nucleoid associated proteins were altered in the PG0121 mutant. Phenotypic and quantitative real-time-PCR (qRT-PCR) analyses determined that under iron-limiting growth conditions, cell division and viability were defective in the PG0121 mutant. Collectively, our studies show that PG0121 does indeed encode a functional HU homologue, and HUβ has global regulatory functions in P. gingivalis; it affects not only production of capsular polysaccharides but also expression of genes involved in basic functions, such as cell wall synthesis, cell division and iron uptake.
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Affiliation(s)
- Richa Priyadarshini
- Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
- Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA
| | - Carla Cugini
- Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
- Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA
| | - Annette Arndt
- Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany
| | - Tsute Chen
- Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
- Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA
| | - Natalia O Tjokro
- Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - Steven D Goodman
- Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA
| | - Mary E Davey
- Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
- Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA
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39
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Zhang Y, Hu Z, Qin H, Wei X, Cheng K, Liu F, Wu R, Zou H. Highly Efficient Extraction of Cellular Nucleic Acid Associated Proteins in Vitro with Magnetic Oxidized Carbon Nanotubes. Anal Chem 2012; 84:10454-62. [DOI: 10.1021/ac302695u] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Yi Zhang
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhengyan Hu
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongqiang Qin
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoluan Wei
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Kai Cheng
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Fangjie Liu
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
- Graduate School of Chinese Academy of Sciences, Beijing 100049, China
| | - Ren’an Wu
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Hanfa Zou
- CAS Key Lab of Separation Sciences for Analytical Chemistry, National Chromatographic R&A Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
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40
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Yee B, Sagulenko E, Morgan GP, Webb RI, Fuerst JA. Electron tomography of the nucleoid of Gemmata obscuriglobus reveals complex liquid crystalline cholesteric structure. Front Microbiol 2012; 3:326. [PMID: 22993511 PMCID: PMC3440768 DOI: 10.3389/fmicb.2012.00326] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 08/23/2012] [Indexed: 11/13/2022] Open
Abstract
The nucleoid of the planctomycete Gemmata obscuriglobus is unique within the Bacteria in being both highly condensed and enclosed by a double-membrane nuclear envelope, seemingly analogous to the nucleus of eukaryotes. Here we have applied electron tomography to study high-pressure frozen, cryosubstituted cells of G. obscuriglobus and found multiple nested orders of DNA organization within the condensed nucleoid structure. Detailed examination of the nucleoid revealed a series of nested arcs characteristic of liquid crystalline cholesteric DNA structure. The finest fibers were arranged in parallel concentrically in a double-twist organization. At the highest order of nucleoid organization, several of these structures come together to form the core of the G. obscuriglobus nucleoid. The complex structure of DNA within this nucleoid may have implications for understanding the evolutionary significance of compartmentalized planctomycete cells.
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Affiliation(s)
- Benjamin Yee
- School of Chemistry and Molecular Biosciences, The University of Queensland St. Lucia, QLD, Australia
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41
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Abstract
Genomic analyses increasingly make use of sophisticated statistical and computational approaches in investigations of genomic function and evolution. Scientists implementing and developing these approaches are often computational scientists, physicists, or mathematicians. This article aims to provide a compact overview of genome biology for these scientists. Thus, the article focuses on providing biological context to the genomic features, processes, and structures analysed by these approaches. Topics covered include (1) differences between eukaryotic and prokaryotic cells; (2) the physical structure of genomes and chromatin; (3) different categories of genomic regions, including those serving as templates for RNA and protein synthesis, regulatory regions, repetitive regions, and "architectural" or "organisational" regions, such as centromeres and telomeres; (4) the cell cycle; (5) an overview of transcription, translation, and protein structure; and (6) a glossary of relevant terms.
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42
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Benza VG, Bassetti B, Dorfman KD, Scolari VF, Bromek K, Cicuta P, Lagomarsino MC. Physical descriptions of the bacterial nucleoid at large scales, and their biological implications. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2012; 75:076602. [PMID: 22790781 DOI: 10.1088/0034-4885/75/7/076602] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Recent experimental and theoretical approaches have attempted to quantify the physical organization (compaction and geometry) of the bacterial chromosome with its complement of proteins (the nucleoid). The genomic DNA exists in a complex and dynamic protein-rich state, which is highly organized at various length scales. This has implications for modulating (when not directly enabling) the core biological processes of replication, transcription and segregation. We overview the progress in this area, driven in the last few years by new scientific ideas and new interdisciplinary experimental techniques, ranging from high space- and time-resolution microscopy to high-throughput genomics employing sequencing to map different aspects of the nucleoid-related interactome. The aim of this review is to present the wide spectrum of experimental and theoretical findings coherently, from a physics viewpoint. In particular, we highlight the role that statistical and soft condensed matter physics play in describing this system of fundamental biological importance, specifically reviewing classic and more modern tools from the theory of polymers. We also discuss some attempts toward unifying interpretations of the current results, pointing to possible directions for future investigation.
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Affiliation(s)
- Vincenzo G Benza
- Dipartimento di Fisica e Matematica, Università dell'Insubria, Como, Italy
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43
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A MatP-divisome interaction coordinates chromosome segregation with cell division in E. coli. EMBO J 2012; 31:3198-211. [PMID: 22580828 DOI: 10.1038/emboj.2012.128] [Citation(s) in RCA: 142] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 04/12/2012] [Indexed: 11/09/2022] Open
Abstract
Initiation of chromosome segregation in bacteria is achieved by proteins acting near the origin of replication. Here, we report that the precise choreography of the terminus region of the Escherichia coli chromosome is also tightly controlled. The segregation of the terminus (Ter) macrodomain (MD) involves the structuring factor MatP. We characterized that migration of the Ter MD from the new pole to mid-cell and its subsequent persistent localization at mid-cell relies on several processes. First, the replication of the Ter DNA is concomitant with its recruitment from the new pole to mid-cell in a sequential order correlated with the position on the genetic map. Second, using a strain carrying a linear chromosome with the Ter MD split in two parts, we show that replisomes are repositioned at mid-cell when replication of the Ter occurs. Third, we demonstrate that anchoring the Ter MD at mid-cell depends on the specific interaction of MatP with the division apparatus-associated protein ZapB. Our results reveal how segregation of the Ter MD is integrated in the cell-cycle control.
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44
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Radhakrishnan SK, Viollier P. Two-in-one: bifunctional regulators synchronizing developmental events in bacteria. Trends Cell Biol 2012; 22:14-21. [DOI: 10.1016/j.tcb.2011.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 09/15/2011] [Accepted: 09/15/2011] [Indexed: 10/16/2022]
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45
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Anuchin AM, Goncharenko AV, Demidenok OI, Kaprelyants AS. Histone-like proteins of bacteria (review). APPL BIOCHEM MICRO+ 2011. [DOI: 10.1134/s0003683811060020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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46
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Collier C, Machón C, Briggs GS, Smits WK, Soultanas P. Untwisting of the DNA helix stimulates the endonuclease activity of Bacillus subtilis Nth at AP sites. Nucleic Acids Res 2011; 40:739-50. [PMID: 21954439 PMCID: PMC3258159 DOI: 10.1093/nar/gkr785] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Bacterial nucleoid associated proteins play a variety of roles in genome maintenance and dynamics. Their involvement in genome packaging, DNA replication and transcription are well documented but it is still unclear whether they play any specific roles in genome repair. We discovered that untwisting of the DNA double helix by bacterial non-specific DNA binding proteins stimulates the activity of a repair endonuclease of the Nth/MutY family involved in abasic site removal during base excision repair. The essential Bacillus subtilis primosomal gene dnaD, coding for a protein with DNA-untwisting activity, is in the same operon with nth and the promoter activity of this operon is transiently stimulated by H(2)O(2). Consequently, dnaD mRNA levels persist high upon treatment with H(2)O(2) compared to the reduced mRNA levels of the other essential primosomal genes dnaB and dnaI, suggesting that DnaD may play an important role in DNA repair in addition to its essential role in replication initiation. Homologous Nth repair endonucleases are found in nearly all organisms, including humans. Our data have wider implications for DNA repair as they suggest that genome associated proteins that alter the superhelicity of the DNA indirectly facilitate base excision repair mediated by repair endonucleases of the Nth/MutY family.
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Affiliation(s)
- Christopher Collier
- Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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47
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Schoen I, Ries J, Klotzsch E, Ewers H, Vogel V. Binding-activated localization microscopy of DNA structures. NANO LETTERS 2011; 11:4008-11. [PMID: 21838238 DOI: 10.1021/nl2025954] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Many nucleic acid stains show a strong fluorescence enhancement upon binding to double-stranded DNA. Here we exploit this property to perform superresolution microscopy based on the localization of individual binding events. The dynamic labeling scheme and the optimization of fluorophore brightness yielded a resolution of ∼14 nm (fwhm) and a spatial sampling of 1/nm. We illustrate our approach with two different DNA-binding dyes and apply it to visualize the organization of the bacterial chromosome in fixed Escherichia coli cells. In general, the principle of binding-activated localization microscopy (BALM) can be extended to other dyes and targets such as protein structures.
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Affiliation(s)
- Ingmar Schoen
- Laboratory for Biologically Oriented Materials, ETH Zurich, Zurich, Switzerland.
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48
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Spitzer J. From water and ions to crowded biomacromolecules: in vivo structuring of a prokaryotic cell. Microbiol Mol Biol Rev 2011; 75:491-506, second page of table of contents. [PMID: 21885682 PMCID: PMC3165543 DOI: 10.1128/mmbr.00010-11] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The interactions and processes which structure prokaryotic cytoplasm (water, ions, metabolites, and biomacromolecules) and ensure the fidelity of the cell cycle are reviewed from a physicochemical perspective. Recent spectroscopic and biological evidence shows that water has no active structuring role in the cytoplasm, an unnecessary notion still entertained in the literature; water acts only as a normal solvent and biochemical reactant. Subcellular structuring arises from localizations and interactions of biomacromolecules and from the growth and modifications of their surfaces by catalytic reactions. Biomacromolecular crowding is a fundamental physicochemical characteristic of cells in vivo. Though some biochemical and physiological effects of crowding (excluded volume effect) have been documented, crowding assays with polyglycols, dextrans, etc., do not properly mimic the compositional variety of biomacromolecules in vivo. In vitro crowding assays are now being designed with proteins, which better reflect biomacromolecular environments in vivo, allowing for hydrophobic bonding and screened electrostatic interactions. I elaborate further the concept of complex vectorial biochemistry, where crowded biomacromolecules structure the cytosol into electrolyte pathways and nanopools that electrochemically "wire" the cell. Noncovalent attractions between biomacromolecules transiently supercrowd biomacromolecules into vectorial, semiconducting multiplexes with a high (35 to 95%)-volume fraction of biomacromolecules; consequently, reservoirs of less crowded cytosol appear in order to maintain the experimental average crowding of ∼25% volume fraction. This nonuniform crowding model allows for fast diffusion of biomacromolecules in the uncrowded cytosolic reservoirs, while the supercrowded vectorial multiplexes conserve the remarkable repeatability of the cell cycle by preventing confusing cross talk of concurrent biochemical reactions.
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Affiliation(s)
- Jan Spitzer
- Mallard Creek Polymers, Inc., 14700 Mallard Creek Road, Charlotte, NC 28262, USA.
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49
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Nir G, Lindner M, Dietrich HRC, Girshevitz O, Vorgias CE, Garini Y. HU protein induces incoherent DNA persistence length. Biophys J 2011; 100:784-790. [PMID: 21281594 DOI: 10.1016/j.bpj.2010.12.3687] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 11/24/2010] [Accepted: 12/02/2010] [Indexed: 11/29/2022] Open
Abstract
HU is a highly conserved protein that is believed to play an important role in the architecture and dynamic compaction of bacterial DNA. Its ability to control DNA bending is crucial for functions such as transcription and replication. The effects of HU on the DNA structure have been studied so far mainly by single molecule methods that require us to apply stretching forces on the DNA and therefore may perturb the DNA-protein interaction. To overcome this hurdle, we study the effect of HU on the DNA structure without applying external forces by using an improved tethered particle motion method. By combining the results with DNA curvature analysis from atomic force microscopy measurements we find that the DNA consists of two different curvature distributions and the measured persistence length is determined by their interplay. As a result, the effective persistence length adopts a bimodal property that depends primarily on the HU concentration. The results can be explained according to a recently suggested model that distinguishes single protein binding from cooperative protein binding.
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Affiliation(s)
- Guy Nir
- Physics Department, Bar Ilan University, Ramat-Gan, Israel; Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel
| | - Moshe Lindner
- Physics Department, Bar Ilan University, Ramat-Gan, Israel; Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel
| | - Heidelinde R C Dietrich
- Department of Imaging Science and Technology, Delft University of Technology, Delft, The Netherlands
| | - Olga Girshevitz
- Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel
| | - Constantinos E Vorgias
- Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Athens, Greece
| | - Yuval Garini
- Physics Department, Bar Ilan University, Ramat-Gan, Israel; Institute for Nanotechnology, Bar Ilan University, Ramat-Gan, Israel.
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50
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Fernández-Sierra M, Delgado-Martí V, Colón-García JE, Quiñones E. A method to estimate the elastic energy stored in braided DNA molecules using hydrodynamic equations. Chem Phys 2011; 383:50-55. [DOI: 10.1016/j.chemphys.2011.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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