Brc1-Mediated Rescue of Smc5/6 Deficiency: Requirement for Multiple Nucleases and a Novel Rad18 Function

Lee, Karen M.; Nizza, Suzanne; Hayes, Tyrone B.; Bass, Kirstin L.; Irmisch, Anja; Murray, Johanne M.; O’Connell, Matthew J.

doi:10.1534/genetics.106.067801

Cited by 33 publications

(75 citation statements)

References 54 publications

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“…28,45,46 These similarities strengthen the connections between Brc1 and the Smc5/6 holocomplex, of which Brc1 was initially discovered as a high-copy suppressor of the smc6-74 hypomorphic allele. 19,20 Brc1 localization in pericentromeric heterochromatin largely depends on the interaction of its C-terminal BRCT domains with γH2A-marked chromatin, although, as we have discovered, the requirement for this interaction for TBZ resistance only becomes obvious when the phosphorylation of histone H2A by Bub1 kinase is also ablated. 28 The new findings reported in this study indicate that the structural integrity of the N-terminal BRCT domains is also important for its functions in replication stress responses and resistance to TBZ (Fig.…”

Section: Discussionmentioning

confidence: 68%

“…Earlier studies suggested that the sensitivity to DNA damaging agents in brc1Δ cells was likely caused by a DNA repair defect, which was consistent with the genetic interactions involving Brc1 and the Smc5/6 holocomplex. [19][20][21] However, a recent study indicated that the requirement for Brc1 more likely involves a role in the resumption of DNA replication at stalled or damaged replication forks. 22 In the case of collapsed replication forks, resumption of DNA replication absolutely depends on homology directed repair.…”

Section: Disclosure Of Potential Conflicts Of Interestmentioning

confidence: 99%

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Brc1 links replication stress response and centromere function

Lee¹,

Russell²

2013

Cell Cycle

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Protection of genome integrity depends on the coordinated activities of DNA replication, DNA repair, chromatin assembly and chromosome segregation mechanisms. DNA lesions are detected by the master checkpoint kinases ATM (Tel1) and ATR (Rad3/ Mec1), which phosphorylate multiple substrates, including a C-terminal SQ motif in histone H2A or H2AX. The 6-BRCT domain protein Brc1, which is required for efficient recovery from replication fork arrest and collapse in fission yeast, binds phospho-histone H2A (γH2A)-coated chromatin at stalled and damaged replication forks. We recently found that Brc1 co-localizes with γH2A that appears in pericentromeric heterochromatin during S-phase. Our studies indicate that Brc1 contributes to the maintenance of pericentromeric heterochromatin, which is required for efficient chromosome segregation during mitosis. Here, we review these studies and present additional results that establish the functional requirements for the N-terminal BRCT domains of Brc1 in the replication stress response and resistance to the microtubule destabilizing drug thiabendazole (TBZ). We also identify the nuclear localization signal (NLS) in Brc1, which closely abuts the C-terminal pair of BRCT domains that form the γH2A-binding pocket. This compact arrangement of localization domains may be a shared feature of other γH2A-binding proteins, including Rtt107, PTIP and Mdc1.

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Section: Discussionmentioning

confidence: 68%

Section: Disclosure Of Potential Conflicts Of Interestmentioning

confidence: 99%

Brc1 links replication stress response and centromere function

Lee¹,

Russell²

2013

Cell Cycle

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“…Genetic epistasis analysis of the suppression of smc6-74 by Brc1 indicates that Brc1 functions in conjunction with the PRR proteins Rhp18 and the TLS polymerases, with the HR machinery, and with multiple structure-specific nucleases (Lee et al, 2007;Sheedy et al, 2005). All of these genes are notable for their function in the processing of stalled and/or collapsed replication forks.…”

Section: Introductionmentioning

confidence: 99%

Brc1-dependent recovery from replication stress

Bass

Murray

O’Connell

2012

Journal of Cell Science

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Summary BRCT-containing protein 1 (Brc1) is a multi-BRCT (BRCA1 carboxyl terminus) domain protein in Schizosaccharomyces pombe that is required for resistance to chronic replicative stress, but whether this reflects a repair or replication defect is unknown and the subject of this study. We show that brc1D cells are significantly delayed in recovery from replication pausing, though this does not activate a DNA damage checkpoint. DNA repair and recombination protein Rad52 is a homologous recombination protein that loads the Rad51 recombinase at resected double-stranded DNA (dsDNA) breaks and is also recruited to stalled replication forks, where it may stabilize structures through its strand annealing activity. Rad52 is required for the viability of brc1D cells, and brc1D cells accumulate Rad52 foci late in S phase that are potentiated by replication stress. However, these foci contain the single-stranded DNA (ssDNA) binding protein RPA, but not Rad51 or cH2A. Further, these foci are not associated with increased recombination between repeated sequences, or increased post-replication repair. Thus, these Rad52 foci do not represent sites of recombination. Following the initiation of DNA replication, the induction of these foci by replication stress is suppressed by defects in origin recognition complex (ORC) function, which is accompanied by loss of viability and severe mitotic defects. This suggests that cells lacking Brc1 undergo an ORC-dependent rescue of replication stress, presumably through the firing of dormant origins, and this generates RPA-coated ssDNA and recruits Rad52. However, as Rad51 is not recruited, and the checkpoint effector kinase Chk1 is not activated, these structures must not contain the unprotected primer ends found at sites of DNA damage that are required for recombination and checkpoint activation. IntroductionDuring DNA replication, cells are extremely vulnerable to DNA damage. This vulnerability is due to both the genomic lesions themselves, but also to the impediment these lesions cause to the completion of replication. Replication forks that encounter sites of DNA damage stall in the face of these lesions, a process that activates the DNA replication checkpoint to help maintain stalled fork stability, halt the cell cycle, and initiate DNA repair. The majority of replication forks are presumed to retain the full complement of replication machinery in a stable conformation at sites of fork stalling until the impeding lesion is repaired. However, some lesions are not readily resolved and so alternative mechanisms for the completion of replication have evolved. These include the collapse of the stalled replication fork and its repair through homologous recombination (HR), bypass of the DNA lesion through the post-replication repair (PRR) pathway, which includes both error-prone and error-free mechanisms, and the completion of replication through the firing of adjacent origins (Branzei and Foiani, 2008;Branzei and Foiani, 2009).PRR mediates lesion bypass through a two-step process. Initia...

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“…Brc1 was initially identified as a high-copy suppressor of smc6-74 (Verkade et al 1999), which encodes a subunit of the essential ''structural maintenance of chromosomes'' Smc5/6 complex that functions in chromosome organization and DNA repair (Lehmann et al 1995;McDonald et al 2003;Harvey et al 2004;Pebernard et al 2004Pebernard et al , 2006. The Brc1-mediated rescue of smc6-74 is thought to proceed via a novel Rhp18-dependent mechanism, utilizing multiple nucleases to facilitate the initial cleavage of abnormal structures that arise due to compromised Smc5/6 function and their subsequent processing by HR (Sheedy et al 2005;Lee et al 2007). Loss of Brc1 function results in sensitivity to a range of DNA-damaging drugs that generate lesions specifically during S-phase or impede DNA replication (Verkade et al 1999;Sheedy et al 2005).…”

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confidence: 99%

Mms22 Preserves Genomic Integrity During DNA Replication in Schizosaccharomyces pombe

Dovey

Russell

2007

Genetics

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The faithful replication of the genome, coupled with the accurate repair of DNA damage, is essential for the maintenance of chromosomal integrity. The MMS22 gene of Saccharomyces cerevisiae plays an important but poorly understood role in preservation of genome integrity. Here we describe a novel gene in Schizosaccharomyces pombe that we propose is a highly diverged ortholog of MMS22. Fission yeast Mms22 functions in the recovery from replication-associated DNA damage. Loss of Mms22 results in the accumulation of spontaneous DNA damage in the S-and G 2 -phases of the cell cycle and elevated genomic instability. There are severe synthetic interactions involving mms22 and most of the homologous recombination proteins but not the structure-specific endonuclease Mus81-Eme1, which is required for survival of broken replication forks. Mms22 forms spontaneous nuclear foci and colocalizes with Rad22 in cells treated with camptothecin, suggesting that it has a direct role in repair of broken replication forks. Moreover, genetic interactions with components of the DNA replication fork suggest that Mms2 functions in the coordination of DNA synthesis following damage. We propose that Mms22 functions directly at the replication fork to maintain genomic integrity in a pathway involving Mus81-Eme1.

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Brc1-Mediated Rescue of Smc5/6 Deficiency: Requirement for Multiple Nucleases and a Novel Rad18 Function

Cited by 33 publications

References 54 publications

Brc1 links replication stress response and centromere function

Brc1 links replication stress response and centromere function

Brc1-dependent recovery from replication stress

Mms22 Preserves Genomic Integrity During DNA Replication in Schizosaccharomyces pombe

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