title: The requirement for the Dam1 complex is dependent upon the number of kinetochore proteins and microtubules.
abstract: The Dam1 complex attaches the kinetochore to spindle microtubules and is a processivity factor in vitro. In Saccharomyces cerevisiae, which has point centromeres that attach to a single microtubule, deletion of any Dam1 complex member results in chromosome segregation failures and cell death. In Schizosaccharomyces pombe, which has epigenetically defined regional centromeres that each attach to 3-5 kinetochore microtubules, Dam1 complex homologs are not essential. To determine why the complex is essential in some organisms and not in others, we used Candida albicans, a multimorphic yeast with regional centromeres that attach to a single microtubule. Interestingly, the Dam1 complex was essential in C. albicans, suggesting that the number of microtubules per centromere is critical for its requirement. Importantly, by increasing CENP-A expression levels, more kinetochore proteins and microtubules were recruited to the centromeres, which remained fully functional. Furthermore, Dam1 complex members became less crucial for growth in cells with extra kinetochore proteins and microtubules. Thus, the requirement for the Dam1 complex is not due to the DNA-specific nature of point centromeres. Rather, the Dam1 complex is less critical when chromosomes have multiple kinetochore complexes and microtubules per centromere, implying that it functions as a processivity factor in vivo as well as in vitro.
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Laura S
authors.initials: LS
authors.lastname: Burrack
authors.forename: Shelly E
authors.initials: SE
authors.lastname: Applen
authors.forename: Judith
authors.initials: J
authors.lastname: Berman
mesh_terms: D001324:Autoantigens / Q000378:metabolism; D015139:Blotting, Southern; D015153:Blotting, Western; D002176:Candida albicans; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism*; D000076247:Centromere Protein A; D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D018386:Kinetochores / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012568:Schizosaccharomyces; D013045:Species Specificity
chemical_list: D001324:Autoantigens; D018797:Cell Cycle Proteins; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; C467729:Cse4 protein, Candida albicans; C116003:DAM1 protein, S cerevisiae; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins