Identification of MMS22 as a regulator of DNA repair

Obstacles such as DNA damage can block the progression of DNA replication forks. This is a major source of genome instability that can lead to cell transformation or death. The budding yeast MMS1 and MMS22 genes were identified in a screen for mutants that were hypersensitive to DNA alkylation that blocks replisome progression. I set out to investigate the cellular roles of these genes and found that cells lacking MMS1 or MMS22 are hypersensitive to a wide variety of genotoxins that stall or block replication forks, and are severely defective in their ability to recover from DNA alkylation damage. Homologous recombination (HR) is an important mechanism for the rescue of stalled or blocked replication forks and for the repair of double-strand breaks (DSBs). Strikingly, MMS1 and MMS22 are required for HR induced by replication stress but not by DSBs, and the underlying mechanisms were explored.I next identified the uncharacterized protein C6ORF167 (MMS22L) as a putative human Mms22 orthologue. MMS22L interacts with NF?BIL2/TONSL, the histone chaperone ASF1 and subunits of the MCM replicative helicase. MMS22L colocalizes with TONSL at perturbed replication forks and at sites of DNA damage. MMS22L and TONSL are important for the repair of collapsed replication forks as depletion of MMS22L or TONSL from human cells causes DNA damage during S–phase and hypersensitivity to agents that cause fork collapse. These defects are consistent with the observations that MMS22L and TONSL are required for the efficient loading of the RAD51 recombinase onto resected DNA ends and for efficient HR. These data indicate that MMS22L and TONSL are novel regulators of genome stability that enable efficient HR.EThOS - Electronic Theses Online ServiceMRCDorothy Hodgkin Postgraduate AwardGBUnited Kingdo

From equator to pole:Splitting chromosomes in mitosis and meiosis

During eukaryotic cell division, chromosomes must be precisely partitioned to daughter cells. This relies on a mechanism to move chromosomes in defined directions within the parental cell. While sister chromatids are segregated from one another in mitosis and meiosis II, specific adaptations enable the segregation of homologous chromosomes during meiosis I to reduce ploidy for gamete production. Many of the factors that drive these directed chromosome movements are known, and their molecular mechanism has started to be uncovered. Here we review the mechanisms of eukaryotic chromosome segregation, with a particular emphasis on the modifications that ensure the segregation of homologous chromosomes during meiosis I

The Molecular Basis of Monopolin Recruitment to the Kinetochore

The monopolin complex is a multifunctional molecular crosslinker, which in S. pombe binds and organises mitotic kinetochores to prevent aberrant kinetochore-microtubule interactions. In the budding yeast S. cerevisiae, whose kinetochores bind a single microtubule, the monopolin complex crosslinks and mono-orients sister kinetochores in meiosis I, enabling the biorientation and segregation of homologs. Here, we show that both the monopolin complex subunit Csm1 and its binding site on the kinetochore protein Dsn1 are broadly distributed throughout eukaryotes, suggesting a conserved role in kinetochore organisation and function. We find that budding yeast Csm1 binds two conserved motifs in Dsn1, one (termed Box 1) representing the ancestral, widely conserved monopolin binding motif and a second (termed Box 2-3) with a likely role in enforcing specificity of sister kinetochore crosslinking. We find that Box 1 and Box 2-3 bind the same conserved hydrophobic cavity on Csm1, suggesting competition or handoff between these motifs. Using structure-based mutants, we also find that both Box 1 and Box 2-3 are critical for monopolin function in meiosis. We identify two conserved serine residues in Box 2-3 that are phosphorylated in meiosis and whose mutation to aspartate stabilises Csm1-Dsn1 binding, suggesting that regulated phosphorylation of these residues may play a role in sister kinetochore crosslinking specificity. Overall, our results reveal the monopolin complex as a broadly conserved kinetochore organiser in eukaryotes, which budding yeast have co-opted to mediate sister kinetochore crosslinking through the addition of a second, regulatable monopolin binding interface

12-month safety and efficacy of everolimus with reduced exposure cyclosporine in de novo renal transplant recipients

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74645/1/j.1432-2277.2006.00414.x.pd

Everolimus with Optimized Cyclosporine Dosing in Renal Transplant Recipients: 6-Month Safety and Efficacy Results of Two Randomized Studies

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74668/1/j.1600-6143.2004.00389.x.pd

The proteomic landscape of centromeric chromatin reveals an essential role for the Ctf19CCAN complex in meiotic kinetochore assembly

Dataset in support of manuscript "The proteomic landscape of centromeric chromatin reveals an essential role for the Ctf19CCAN complex in meiotic kinetochore assembly" in submission to Mol. Cell. The dataset comprises of a set of interactive volcano plots related to the figures in the manuscript. These files allow interaction with data. Press any element of the legend to disable the indicated subset of proteins. Hover over each datapoint to display protein names.Borek, Weronika; Marston, Adele; Duro, Eris. (2020). The proteomic landscape of centromeric chromatin reveals an essential role for the Ctf19CCAN complex in meiotic kinetochore assembly, [dataset]. University of Edinburgh. School of Biology. https://doi.org/10.7488/ds/2850

The repertoire of minimal mobile elements in the Neisseria species and evidence that these are involved in horizontal gene transfer in other bacteria

In the Neisseria spp., natural competence for transformation and homologous recombination generate antigenic variants through creation of mosaic genes (such as opas) and through recombination with silent cassettes (such as pilE/pilS) and gene-complement diversity through the horizontal exchange of whole genes or groups of genes, in minimal mobile elements (MMEs). An MME is a region encompassing 2 conserved genes between which different whole-gene cassettes are found in different strains, which are chromosomally incorporated solely through the action of homologous recombination. Comparative analyses of the neisserial genome sequences identified 39 potential MME sites, the contents of which were investigated in 11 neisserial strains. One hundred and eight different MME regions were identified, 20 of which contain novel sequences and these contain 12 newly identified neisserial coding sequences. Neisserial uptake signal sequences are associated with 38 of the 40 MMEs studied. In some sites, divergent dinucleotide signatures of the sequences between the flanking genes suggest relatively recent horizontal acquisition of some cassettes. The neisserial MMEs were used to interrogate all of the other available bacterial genome sequences, revealing frequent conservation of the flanking genes combined with the presence of different gene cassettes between them. In some cases, these sites can definitively be classified as MMEs in these other genera. These findings provide additional evidence for the MME model, indicate that MME-directed investigations are a good basis for the identification of novel strain-specific genes and differences within bacterial populations and demonstrate that these elements are probably ubiquitously involved in genetic exchange, particularly in naturally competent bacteria

The proteomic landscape of centromeric chromatin reveals an essential role for the Ctf19CCAN complex in meiotic kinetochore assembly (2020)

This is supplementary data accompanying a manuscript submission. Recent work on the same topic is described in a pre-print: "The proteomic landscape of centromeric chromatin reveals an essential role for the Ctf19CCAN complex in meiotic kinetochore assembly" Weronika E. Borek, Nadine Vincenten, Eris Duro, Vasso Makrantoni, Christos Spanos, Krishna K. Sarangapani, Flavia de Lima Alves, David A. Kelly, Charles L. Asbury, Juri Rappsilber, Adele L. Marston bioRxiv 2020.06.23.167395; doi: https://doi.org/10.1101/2020.06.23.167395