ScII: an abundant chromosome scaffold protein is a member of a family of putative ATPases with an unusual predicted tertiary structure.
Here, we describe the cloning and characterization of ScII, the second most abundant protein after topoisomerase II, of the chromosome scaffold fraction to be identified. ScII is structurally related to a protein, Smc1p, previously found to be required for accurate chromosome segregation in Saccharomyces cerevisiae. ScII and the other members of the emerging family of SMC1-like proteins are likely to be novel ATPases, with NTP-binding A and B sites separated by two lengthy regions predicted to form an alpha-helical coiled-coil. Analysis of the ScII B site predicted that ScII might use ATP by a mechanism similar to the bacterial recN DNA repair and recombination enzyme. ScII is a mitosis-specific scaffold protein that colocalizes with topoisomerase II in mitotic chromosomes. However, ScII appears not to be associated with the interphase nuclear matrix. ScII might thus play a role in mitotic processes such as chromosome condensation or sister chromatid disjunction, both of which have been previously shown to involve topoisomerase II.
Saitoh
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Department of Cell Biology and Anatomy, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
Goldberg
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Wood
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Earnshaw
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WC
D000251:Adenosine Triphosphatases / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D030161:Avian Proteins; D001483:Base Sequence; D001665:Binding Sites; D018797:Cell Cycle Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D002842:Chromatids / Q000737:chemistry; D002868:Chromosomal Proteins, Non-Histone; D002875:Chromosomes / Q000737:chemistry*; D003001:Cloning, Molecular; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry; D007399:Interphase; D008938:Mitosis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015530:Nuclear Matrix / Q000737:chemistry; D009687:Nuclear Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009711:Nucleotides / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry; D000098550:Structural Maintenance of Chromosome Protein 1
D030161:Avian Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; D009711:Nucleotides; C089784:ScII protein, Gallus gallus; D000098550:Structural Maintenance of Chromosome Protein 1; D000251:Adenosine Triphosphatases; D004250:DNA Topoisomerases, Type II