title: Involvement of nucleocytoplasmic shuttling of yeast Nap1 in mitotic progression.
abstract: Nucleosome assembly protein 1 (Nap1) is widely conserved from yeasts to humans and facilitates nucleosome formation in vitro as a histone chaperone. Nap1 is generally localized in the cytoplasm, except that subcellular localization of Drosophila melanogaster Nap1 is dynamically regulated between the cytoplasm and nucleus during early development. The cytoplasmic localization of Nap1 is seemingly incompatible with the proposed role of Nap1 in nucleosome formation, which should occur in the nucleus. Here, we have examined the roles of a putative nuclear export signal (NES) sequence in yeast Nap1 (yNap1). yNap1 mutants lacking the NES-like sequence were localized predominantly in the nucleus. Deletion of NAP1 in cells harboring a single mitotic cyclin gene is known to cause mitotic delay and temperature-sensitive growth. A wild-type NAP1 complemented these phenotypes while nap1 mutant genes lacking the NES-like sequence or carboxy-terminal region did not. These and other results suggest that yNap1 is a nucleocytoplasmic shuttling protein and that its shuttling is important for yNap1 function during mitotic progression. This study also provides a possible explanation for Nap1's involvement in nucleosome assembly and/or remodeling in the nucleus.
authors.affiliation: Department of Infection Biology, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-8575, Japan.
authors.forename: Mary
authors.initials: M
authors.lastname: Miyaji-Yamaguchi
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kato
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Nakano
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Akashi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kikuchi
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Nagata
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000595:Amino Acid Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005816:Genetic Complementation Test; D006657:Histones / Q000378:metabolism; D008938:Mitosis; D008969:Molecular Sequence Data; D009154:Mutation; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056490:Nucleosome Assembly Protein 1; D009707:Nucleosomes / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D028961:beta Karyopherins
chemical_list: C093749:CLB2 protein, S cerevisiae; D018797:Cell Cycle Proteins; C503698:CycB protein, Drosophila; D019926:Cyclin B; D029721:Drosophila Proteins; D005656:Fungal Proteins; D006657:Histones; C400425:KAP114 protein, S cerevisiae; C533556:NAP1 protein, S cerevisiae; C533557:NAP1L1 protein, human; C533554:Nap1 protein, Drosophila; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D056490:Nucleosome Assembly Protein 1; D009707:Nucleosomes; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D028961:beta Karyopherins