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  1. Artikel ; Online: On the stability of stalled RNA polymerase and its removal by RapA.

    Portman, James R / Qayyum, M Zuhaib / Murakami, Katsuhiko S / Strick, Terence R

    Nucleic acids research

    2022  Band 50, Heft 13, Seite(n) 7396–7405

    Abstract: Stalling of the transcription elongation complex formed by DNA, RNA polymerase (RNAP) and RNA presents a serious obstacle to concurrent processes due to the extremely high stability of the DNA-bound polymerase. RapA, known to remove RNAP from DNA in an ... ...

    Abstract Stalling of the transcription elongation complex formed by DNA, RNA polymerase (RNAP) and RNA presents a serious obstacle to concurrent processes due to the extremely high stability of the DNA-bound polymerase. RapA, known to remove RNAP from DNA in an ATP-dependent fashion, was identified over 50 years ago as an abundant binding partner of RNAP; however, its mechanism of action remains unknown. Here, we use single-molecule magnetic trapping assays to characterize RapA activity and begin to specify its mechanism of action. We first show that stalled RNAP resides on DNA for times on the order of 106 seconds and that increasing positive torque on the DNA reduces this lifetime. Using stalled RNAP as a substrate we show that the RapA protein stimulates dissociation of stalled RNAP from positively supercoiled DNA but not negatively supercoiled DNA. We observe that RapA-dependent RNAP dissociation is torque-sensitive, is inhibited by GreB and depends on RNA length. We propose that stalled RNAP is dislodged from DNA by RapA via backtracking in a supercoiling- and torque-dependent manner, suggesting that RapA's activity on transcribing RNAP in vivo is responsible for resolving conflicts between converging polymerase molecular motors.
    Mesh-Begriff(e) DNA, Superhelical/metabolism ; DNA-Directed RNA Polymerases/metabolism ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Escherichia coli Proteins/metabolism ; RNA/genetics ; RNA/metabolism ; Transcription, Genetic
    Chemische Substanzen DNA, Superhelical ; Escherichia coli Proteins ; RapA protein, E coli ; RNA (63231-63-0) ; DNA-Directed RNA Polymerases (EC 2.7.7.6)
    Sprache Englisch
    Erscheinungsdatum 2022-07-12
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 186809-3
    ISSN 1362-4962 ; 1362-4954 ; 0301-5610 ; 0305-1048
    ISSN (online) 1362-4962 ; 1362-4954
    ISSN 0301-5610 ; 0305-1048
    DOI 10.1093/nar/gkac558
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  2. Artikel ; Online: Transcription-Coupled Repair and Complex Biology.

    Portman, James R / Strick, Terence R

    Journal of molecular biology

    2018  Band 430, Heft 22, Seite(n) 4496–4512

    Abstract: All active living organisms mitigate DNA damage via DNA repair, and the so-called nucleotide excision repair pathway represents a functionally major part of the cell's DNA repair repertoire [1]. In this pathway, the damaged strand of DNA is incised and ... ...

    Abstract All active living organisms mitigate DNA damage via DNA repair, and the so-called nucleotide excision repair pathway represents a functionally major part of the cell's DNA repair repertoire [1]. In this pathway, the damaged strand of DNA is incised and removed before being resynthesized. This form of DNA repair requires a multitude of proteins working in a complex choreography. Repair thus typically involves detection of a DNA lesion, validation of that detection event, search for an appropriate incision site and subsequent DNA incision, DNA unwinding/removal, and DNA resynthesis and religation. These activities are ultimately the result of molecules randomly diffusing and bumping into each other and acting in succession. It is also true, however, that repair components are often assembled into functional complexes which may be more efficient or regular in their mode of action. Studying DNA repair complexes for their mechanisms of assembly, action, and disassembly can help address fundamental questions such as whether DNA repair pathways are branched or linear; whether, for instance, they tolerate fluctuations in numbers of components; and more broadly how search processes between macromolecules take place or can be enhanced.
    Mesh-Begriff(e) Animals ; DNA Damage ; DNA Repair ; Humans ; Models, Molecular ; Multiprotein Complexes/metabolism ; Protein Transport ; Single Molecule Imaging ; Transcription, Genetic
    Chemische Substanzen Multiprotein Complexes
    Sprache Englisch
    Erscheinungsdatum 2018-05-04
    Erscheinungsland England
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 80229-3
    ISSN 1089-8638 ; 0022-2836
    ISSN (online) 1089-8638
    ISSN 0022-2836
    DOI 10.1016/j.jmb.2018.04.033
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  3. Artikel ; Online: Cotranscriptional R-loop formation by Mfd involves topological partitioning of DNA.

    Portman, James R / Brouwer, Gwendolyn M / Bollins, Jack / Savery, Nigel J / Strick, Terence R

    Proceedings of the National Academy of Sciences of the United States of America

    2021  Band 118, Heft 15

    Abstract: R-loops are nucleic acid hybrids which form when an RNA invades duplex DNA to pair with its template sequence. Although they are implicated in a growing number of gene regulatory processes, their mechanistic origins remain unclear. We here report real- ... ...

    Abstract R-loops are nucleic acid hybrids which form when an RNA invades duplex DNA to pair with its template sequence. Although they are implicated in a growing number of gene regulatory processes, their mechanistic origins remain unclear. We here report real-time observations of cotranscriptional R-loop formation at single-molecule resolution and propose a mechanism for their formation. We show that the bacterial Mfd protein can simultaneously interact with both elongating RNA polymerase and upstream DNA, tethering the two together and partitioning the DNA into distinct supercoiled domains. A highly negatively supercoiled domain forms in between Mfd and RNA polymerase, and compensatory positive supercoiling appears in front of the RNA polymerase and behind Mfd. The nascent RNA invades the negatively supercoiled domain and forms a stable R-loop that can drive mutagenesis. This mechanism theoretically enables any protein that simultaneously binds an actively translocating RNA polymerase and upstream DNA to stimulate R-loop formation.
    Mesh-Begriff(e) Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; DNA-Directed RNA Polymerases/metabolism ; Escherichia coli ; Mutation ; R-Loop Structures ; Single Molecule Imaging ; Transcription Factors/genetics ; Transcription Factors/metabolism ; Transcription, Genetic
    Chemische Substanzen Bacterial Proteins ; Transcription Factors ; transcription repair coupling factor protein, Bacteria ; DNA-Directed RNA Polymerases (EC 2.7.7.6)
    Sprache Englisch
    Erscheinungsdatum 2021-04-08
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2019630118
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  4. Artikel ; Online: Modulation of SARS-CoV-2 spike binding to ACE2 through conformational selection

    Saha, Prithwidip / Fernanadez, Ignacio / Sumbul, Fidan / Valotteau, Claire / Kostrz, Dorota / Meola, Annalisa / Baquero, Eduard / Sharma, Arvind / Portman, James R. / Stransky, Francois / Boudier, Thomas / Guardado Calvo, Pablo / Gosse, Charlie / Strick, Terence / Rey, Felix A. / Rico, Felix

    bioRxiv

    Abstract: The first step of SARS-CoV-2 infection involves the interaction between the trimeric viral spike protein () and the host angiotensin-converting enzyme 2 (2). The receptor binding domain () of adopts two conformations: open and closed, respectively, ... ...

    Abstract The first step of SARS-CoV-2 infection involves the interaction between the trimeric viral spike protein () and the host angiotensin-converting enzyme 2 (2). The receptor binding domain () of adopts two conformations: open and closed, respectively, accessible and inaccessible to 2. Therefore, motions are suspected to affect 2 binding; yet a quantitative description of the underlying mechanism has been elusive. Here, using single-molecule approaches, we visualize opening and closing and probe the /2 interaction. Our results show that RBD dynamics affect 2 binding but not unbinding. The resulting modulation is quantitatively predicted by a conformational selection model in which each protomer behaves independently. Our work reveals a general molecular mechanism affecting binding affinity without altering binding strength, helping to understand coronavirus infection and immune evasion.
    Schlagwörter covid19
    Sprache Englisch
    Erscheinungsdatum 2024-03-18
    Verlag Cold Spring Harbor Laboratory
    Dokumenttyp Artikel ; Online
    DOI 10.1101/2024.03.15.585207
    Datenquelle COVID19

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