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Lia G, Praly E, Ferreira H, Stockdale C, Tse-Dinh YC, Dunlap D, Croquette V, Bensimon D, Owen-Hughes T. Direct observation of DNA distortion by the RSC complex. Mol Cell 2006; 21:417-25. [PMID: 16455496 PMCID: PMC3443744 DOI: 10.1016/j.molcel.2005.12.013] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2005] [Revised: 12/05/2005] [Accepted: 12/13/2005] [Indexed: 11/21/2022]
Abstract
The Snf2 family represents a functionally diverse class of ATPase sharing the ability to modify DNA structure. Here, we use a magnetic trap and an atomic force microscope to monitor the activity of a member of this class: the RSC complex. This enzyme caused transient shortenings in DNA length involving translocation of typically 400 bp within 2 s, resulting in the formation of a loop whose size depended on both the force applied to the DNA and the ATP concentration. The majority of loops then decrease in size within a time similar to that with which they are formed, suggesting that the motor has the ability to reverse its direction. Loop formation was also associated with the generation of negative DNA supercoils. These observations support the idea that the ATPase motors of the Snf2 family of proteins act as DNA translocases specialized to generate transient distortions in DNA structure.
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Affiliation(s)
- Giuseppe Lia
- Laboratoire de Physique Statistique and Department Biologie, Ecole Normale Supérieure, CNRS-UMR 8550, 24 rue Lhomond, 75231 Paris Cedex 05, France
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Abstract
The fundamental problems in duplicating and transmitting genetic information posed by the geometric and topological features of DNA, combined with its large size, are qualitatively similar for prokaryotic and eukaryotic chromosomes. The evolutionary solutions to these problems reveal common themes. However, depending on differences in their organization, ploidy, and copy number, chromosomes and plasmids display distinct segregation strategies as well. In bacteria, chromosome duplication, likely mediated by a stationary replication factory, is accompanied by rapid, directed migration of the daughter duplexes with assistance from DNA-compacting and perhaps translocating proteins. The segregation of unit-copy or low-copy bacterial plasmids is also regulated spatially and temporally by their respective partitioning systems. Eukaryotic chromosomes utilize variations of a basic pairing and unpairing mechanism for faithful segregation during mitosis and meiosis. Rather surprisingly, the yeast plasmid 2-micron circle also resorts to a similar scheme for equal partitioning during mitosis.
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Affiliation(s)
- Santanu Kumar Ghosh
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712-0612, USA.
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Cabezon E, de la Cruz F. TrwB: an F(1)-ATPase-like molecular motor involved in DNA transport during bacterial conjugation. Res Microbiol 2005; 157:299-305. [PMID: 16427770 DOI: 10.1016/j.resmic.2005.12.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 12/01/2005] [Accepted: 12/07/2005] [Indexed: 11/15/2022]
Abstract
The mechanism by which TrwB acts as a DNA transporter in bacterial conjugation is analyzed. Based on a parallelism between TrwB and F(1)-ATPase, TrwB would use the energy derived from ATP hydrolysis to pump DNA through its central channel, in a manner similar to that used by F(1)-ATPase to produce a rotary movement of the central gamma-subunit.
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Affiliation(s)
- Elena Cabezon
- Departamento de Biología Molecular (Unidad Asociada al CIB-CSIC), Universidad de Cantabria, C. Herrera Oria s/n, 39011 Santander, Spain
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Bigot S, Saleh OA, Lesterlin C, Pages C, El Karoui M, Dennis C, Grigoriev M, Allemand JF, Barre FX, Cornet F. KOPS: DNA motifs that control E. coli chromosome segregation by orienting the FtsK translocase. EMBO J 2005; 24:3770-80. [PMID: 16211009 PMCID: PMC1276719 DOI: 10.1038/sj.emboj.7600835] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Accepted: 09/14/2005] [Indexed: 11/09/2022] Open
Abstract
Bacterial chromosomes are organized in replichores of opposite sequence polarity. This conserved feature suggests a role in chromosome dynamics. Indeed, sequence polarity controls resolution of chromosome dimers in Escherichia coli. Chromosome dimers form by homologous recombination between sister chromosomes. They are resolved by the combined action of two tyrosine recombinases, XerC and XerD, acting at a specific chromosomal site, dif, and a DNA translocase, FtsK, which is anchored at the division septum and sorts chromosomal DNA to daughter cells. Evidences suggest that DNA motifs oriented from the replication origin towards dif provide FtsK with the necessary information to faithfully distribute chromosomal DNA to either side of the septum, thereby bringing the dif sites together at the end of this process. However, the nature of the DNA motifs acting as FtsK orienting polar sequences (KOPS) was unknown. Using genetics, bioinformatics and biochemistry, we have identified a family of DNA motifs in the E. coli chromosome with KOPS activity.
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Affiliation(s)
- Sarah Bigot
- LMGM, CNRS, 118, route de Narbonne, Toulouse, France
| | | | | | - Carine Pages
- LMGM, CNRS, 118, route de Narbonne, Toulouse, France
| | | | | | | | | | - François-Xavier Barre
- LMGM, CNRS, 118, route de Narbonne, Toulouse, France
- CGM, CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France. Tel.: +33 169 82 32 24; Fax: +33 169 82 31 60; E-mail:
| | - François Cornet
- LMGM, CNRS, 118, route de Narbonne, Toulouse, France
- LMGM, CNRS, 118, route de Narbonne, 31062 Toulouse Cedex, France. Tel.: +33 561 335 986; Fax: +33 561 335 886; E-mail:
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