The tale of SSB

Bianco, Piero R.

doi:10.1016/j.pbiomolbio.2016.11.001

Cited by 69 publications

(128 citation statements)

References 65 publications

(92 reference statements)

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“…The C-terminal domain of SSB can be further subdivided into two subdomains: a sequence of approximately 54 residues comprising residues 116-170, that is known as the linker and, the last eight residues which are known as the acidic tip (Kozlov et al, 2015;Shereda et al, 2008). The linker contains several structural elements critical to its function, including PXXP motifs (Bianco, 2017;Bianco et al, 2017;Tan et al, 2017). Critical to SSB function, the PXXP motifs in the linkers of one tetramer bind to the OB-fold(s) present in a nearby tetramer thereby facilitating cooperative ssDNA binding (Bianco, 2017;Bianco et al, 2017;Tan et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Super‐resolution imaging reveals changes in Escherichia coli SSB localization in response to DNA damage

Zhao

Liu

Wang³

et al. 2019

Genes to Cells

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The E. coli single‐stranded DNA‐binding protein (SSB) is essential to viability. It plays key roles in DNA metabolism where it binds to nascent single strands of DNA and to target proteins known as the SSB interactome. There are >2,000 tetramers of SSB per cell with 100–150 associated with the genome at any one time, either at DNA replication forks or at sites of repair. The remaining 1,900 tetramers could constantly diffuse throughout the cytosol or be associated with the inner membrane as observed for other DNA metabolic enzymes. To visualize SSB localization and to ascertain potential spatiotemporal changes in response to DNA damage, SSB‐GFP chimeras were visualized using a novel, super‐resolution microscope optimized for the study of prokaryotic cells. In the absence of DNA damage, SSB localizes to a small number of foci and the excess protein is associated with the inner membrane where it binds to the major phospholipids. Within five minutes following DNA damage, the vast majority of SSB disengages from the membrane and is found almost exclusively in the cell interior. Here, it is observed in a large number of foci, in discreet structures or, in diffuse form spread over the genome, thereby enabling repair events.

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Section: Introductionmentioning

confidence: 99%

Super‐resolution imaging reveals changes in Escherichia coli SSB localization in response to DNA damage

Zhao

Liu

Wang³

et al. 2019

Genes to Cells

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“…We proposed that the PXXP-OB fold interaction involving SSB is analogous to the SH3-PXXP binding that occurs in eukaryotic systems and have taken advantage of in RecG loading. 31,32 If the IDL-OB-fold model is correct, and if SSB tetramers are linked to one another on a single stranded DNA molecule, then it is likely that changes in the IDL would impact several DNA metabolic processes in which SSB is involved. To test this, we examined the activities of various enzymes in the presence of WtSSB and the linker deletion mutants used previously.…”

Section: Introductionmentioning

confidence: 99%

The intrinsically disordered linker of E. coliSSB is critical for the release from single‐stranded DNA

et al. 2017

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The Escherichia coli single stranded DNA binding protein (SSB) is crucial for DNA replication, recombination and repair. Within each process, it has two seemingly disparate roles: it stabilizes single-stranded DNA (ssDNA) intermediates generated during DNA processing and, forms complexes with a group of proteins known as the SSB-interactome. Key to both roles is the C-terminal, one-third of the protein, in particular the intrinsically disordered linker (IDL). Previously, they have shown using a series of linker deletion mutants that the IDL links both ssDNA and target protein binding by mediating interactions with the oligosaccharide/oligonucleotide binding fold in the target. In this study, they examine the role of the linker region in SSB function in a variety of DNA metabolic processes in vitro. Using the same linker mutants, the results show that in addition to association reactions (either DNA or protein), the IDL is critical for the release of SSB from DNA. This release can be under conditions of ssDNA competition or active displacement by a DNA helicase or recombinase. Consistent with their previous work these results indicate that SSB linker mutants are defective for SSB-SSB interactions, and when the IDL is removed a terminal SSB-DNA complex results. Formation of this complex inhibits downstream processing of DNA by helicases such as RecG or PriA as well as recombination, mediated by RecA. A model, based on the evidence herein, is presented to explain how the IDL acts in SSB function.

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“…Biochemical and genetic studies have shown that SSB and RPA protect the ssDNA from nucleases, eliminate secondary structure to enable recombinase loading, serve as DNA damage signalling complexes and promote recruitment of downstream factors 64,66–71 (FIG. 1).…”

Section: Sm-based Insights Into Recombinationmentioning

confidence: 99%

A change of view: homologous recombination at single-molecule resolution

2017

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Genetic recombination occurs in all organisms and is vital for genome stability. Indeed, in humans, aberrant recombination can lead to diseases such as cancer. Our understanding of homologous recombination is built upon more than a century of scientific inquiry, but achieving a more complete picture using ensemble biochemical and genetic approaches is hampered by population heterogeneity and transient recombination intermediates. Recent advances in single-molecule and super-resolution microscopy methods help to overcome these limitations and have led to new and refined insights into recombination mechanisms, including a detailed understanding of DNA helicase function and synaptonemal complex structure. The ability to view cellular processes at single-molecule resolution promises to transform our understanding of recombination and related processes.

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The tale of SSB

Cited by 69 publications

References 65 publications

Super‐resolution imaging reveals changes in Escherichia coli SSB localization in response to DNA damage

Super‐resolution imaging reveals changes in Escherichia coli SSB localization in response to DNA damage

The intrinsically disordered linker of E. coliSSB is critical for the release from single‐stranded DNA

A change of view: homologous recombination at single-molecule resolution

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