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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The Saccharomyces cerevisiae DNA-binding protein RAP1 is capable of binding in vitro to sequences from a wide variety of genomic loci, including upstream activating sequence elements, the HML and HMR silencer regions, and the poly(G1-3T) tracts of telomeres. Recent biochemical and genetic studies have suggested that RAP1 physically and functionally interacts with the yeast telomere. To further investigate the role of RAP1 at the telomere, we have identified and characterized three intragenic suppressors of a temperature-sensitive allele of RAP1, rap1-5. These telomere deficiency (rap1t) alleles confer several novel phenotypes. First, telomere tract size elongates to up to 4 kb greater than sizes of wild-type or rap1-5 telomeres. Second, telomeres are highly unstable and are subject to rapid, but reversible, deletion of part or all of the increase in telomeric tract length. Telomeric deletion does not require the RAD52 or RAD1 gene product. Third, chromosome loss and nondisjunction rates are elevated 15- to 30-fold above wild-type levels. Sequencing analysis has shown that each rap1t allele contains a nonsense mutation within a discrete region between amino acids 663 and 684. Mobility shift and Western immunoblot analyses indicate that each allele produces a truncated RAP1 protein, lacking the C-terminal 144 to 165 amino acids but capable of efficient DNA binding. These data suggest that RAP1 is a central regulator of both telomere and chromosome stability and define a C-terminal domain that, while dispensable for viability, is required for these telomeric functions.
Mol Cell Biol 1992 Nov
PMID:C-terminal truncation of RAP1 results in the deregulation of telomere size, stability, and function in Saccharomyces cerevisiae. 140 88

Three hundred fifteen radiation hybrids (RH) were isolated using a monochromosomal cell hybrid containing chromosome 16 only. A panel of 18 RH, which showed breakpoints among four markers (3.15, 26.6, 3'HVR, and 5'HVR) mapping in the distal portion of 16p, were selected and characterized for the retention of nine additional DNA sequences already localized in this region, and for one centromeric sequence. One or more breakpoints were identified in nine of the 12 intervals defined by the 13 single-copy sequences used. This panel of RH represents a tool for the construction of a detailed physical map of the distal part of 16p and for cloning sequences located in the proximity of disease genes. Three inter-Alu DNA sequences, amplified from one of these RH containing the autosomal dominant polycystic kidney disease (PKD1) gene, were cloned and mapped in the panel. Sequencing of the ends of one of three clones showed a (CAAA)n repeat, which revealed a two-allele polymorphism.
Somat Cell Mol Genet 1992 Jul
PMID:Radiation hybrids for mapping and cloning DNA sequences of distal 16p. 144 54

We have analysed the sequence organization of the DNA in the pericentric region of the long arm of the human Y chromosome. The structures of one cosmid and three yeast artificial chromosome clones were determined. The region consists of a mosaic of the known 5, 48 and 68 base-pair tandemly repeated sequences and at least five novel repeated sequence families. A long range-map of approximately 3.5 x 10(6) base-pairs of genomic DNA was constructed that placed the clones between about 500 x 10(3) and 850 x 10(3) base-pairs from the long arm edge of the centromeric alphoid DNA array.
J Mol Biol 1992 Nov 20
PMID:Structure of the pericentric long arm region of the human Y chromosome. 145 53

ors12, an 812-bp-long sequence, previously isolated by extrusion of nascent DNA from replication bubbles active at the onset of S phase (G. Kaufmann, M. Zannis-Hadzopoulus, and R. G. Martin Mol. Cell. Biol. 5, 721-727, 1985), has been shown to function as an origin of DNA replication in autonomously replicating plasmids (L. Frappier and M. Zannis-Hadjopoulos Proc. Natl. Acad. Sci. USA 84, 6668-6672, 1987) and in a cell-free system (C. E. Pearson, L. Frappier, and M. Zannis-Hadzopoulos Biochim. Biophys. Acta 1090, 156-166, 1991). A portion of ors12 (nucleotides 1-168) consists of the highly reiterated alpha-satellite sequence (B. S. Rao et al. Gene 87, 233-242, 1990). We have estimated the copy number of the non-alpha-satellite portion of ors12 in CV-1 cells to be < 9 copies per haploid genome and have used it as a probe to generate a genomic map of ors12 on CV-1 DNA. In situ hybridization of CV-1 metaphase chromosomes, using a biotinylated probe of the entire ors12 sequence, positively identified the centromeres of all chromosomes. However, when the non-alpha-satellite portion of ors12 was used as a probe, it positively identified the centromeric region of only six chromosomes, namely, B4, C11, D14, D24, E25, and E27, as well as that of a marker chromosome. The results suggest that ors12 represents a centromeric putative replication origin that is present on a subset of CV-1 chromosomes and is activated at the onset of S phase.
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PMID:ORS12, a mammalian autonomously replicating DNA sequence, is present at the centromere of CV-1 cell chromosomes. 145 4

Histoplasma capsulatum is a dimorphic pathogenic fungus that is a major cause of respiratory and systemic mycosis. We previously developed a transformation system for Histoplasma and demonstrated chromosomal integration of transforming plasmid sequences. In this study, we describe another Histoplasma mechanism for maintaining transforming DNA i.e. the generation of modified, multicopy linear plasmids carrying DNA from the transforming Escherichia coli plasmid. Under selective conditions, these linear plasmids were stable and capable of retransforming Histoplasma without further modification. In vivo modification of the transforming DNA included duplication of plasmid sequence and telomeric addition at the termini of linear DNA. Apparently Histoplasma telomerase, like that of other organisms such as humans and Tetrahymena, is able to act on non-telomeric substrates. The terminus of a Histoplasma linear plasmid was cloned and shown to contain multiple repeats of GGGTTA, the telomeric repeat unit also found in vertebrates, trypanosomes, and slime moulds.
Mol Microbiol 1992 Dec
PMID:In vivo generation of linear plasmids with addition of telomeric sequences by Histoplasma capsulatum. 147 2

Borrelia hermsii, a relapsing fever agent, undergoes multiphasic antigenic variation to evade its host's immune response. Serotype specificity is determined by variable membrane lipoproteins, Vmps, which are expressed from genes located near the end of a linear plasmid. Using the polymerase chain reaction and primers representing the promoter of the active vmp and a conserved telomeric sequence, we characterized the subtelomeric expression regions of the 25 known serotypes of strain HS1. The distance from the promoter to the telomere fell into three size classes of approximately 1.0, 1.5, and 2.5 kilobases. In the sequenced serotypes the size differences were accounted for by variable lengths of the vmp genes and intervening sequences between 3' end of the vmp gene and the start of a downstream homology block. The degree of nucleotide identity between different vmp genes, or between the different 3' flanking DNA varied from 39-78%. Thus, there is length and sequence variability not only between vmp genes themselves but also between the 3' flanking regions of vmp genes.
Mol Microbiol 1992 Nov
PMID:Subtelomeric expression regions of Borrelia hermsii linear plasmids are highly polymorphic. 148 86

Radiation hybrids were produced from a monochromosomal microcell hybrid (PK87-9) which contains only human chromosome 9 with an inserted marker on 9p. Doses of radiation ranging from 1000 to 8000 rads were used to produce a series of hybrids with different size fragments of human chromosome 9. The inserted dominant selectable marker was used to select for hybrids that preferentially maintain fragments of 9p. A panel of 53 radiation hybrids were characterized for 17 chromosome 9 markers. In addition, 17 hybrids were analyzed by fluorescent in situ hybridization (FISH). Hybrids were produced with breaks on both 9p and 9q, many of which appear to contain a single fragment of human chromosome 9. These hybrid cell lines were used to regionally localize 31 cosmids isolated from a chromosome 9 cosmid library. Six cosmids were mapped to intervals on 9p, six cosmids mapped to the centromeric region of the chromosome, and 19 mapped to 9q.
Somat Cell Mol Genet 1992 May
PMID:Construction and characterization of radiation hybrids for chromosome 9, and their use in mapping cosmid probes on the chromosome. 149 23

Human autoantibodies were used to localize centromere proteins by immunoelectron microscopy, immunofluorescence, and confocal microscopy in isolated cells and in cryosections of rabbit testis. A computer-assisted three-dimensional reconstruction of the positions and sizes of fluorescent spots allowed us to follow their movements during the different phases of spermiogenesis. In very young spermatids, the centromeres were distributed within a space separated from both the external nuclear limits and the nuclear core. They moved towards the nuclear center in cap phase spermatids, where they clustered into a few large centromeric masses. In preelongating spermatids, the immunolabeled proteins were dispersed within an equatorial area, where they formed one large mass. In late spermatids, the mass moved towards the posterior part of the nucleus, and, in the spermatozoon, the two basal knobs located at the base of the nuclei were the only strongly immunolabeled structures, while no labeling of the main part of the nucleus was observed. Since the number of centromeres remained close to the number of chromosomes until the cap phase of spermatid differentiation, we hypothesize that the labeling of young spermatids corresponds to centrometric proteins associated with their specific DNA counterparts, while the centromere proteins, possibly detached from their DNA loci, were released from nuclei of old spermatids in the same way as are histones and transition proteins.
Mol Reprod Dev 1992 Aug
PMID:Migration of centromere proteins in rabbit spermatids. 149 85

The 120 bp of yeast centromeric DNA is tightly complexed with protein to form a nuclease-resistant core structure 200 to 240 bp in size. We have used two-dimensional agarose gel electrophoresis to analyze the replication of the chromosomal copies of yeast CEN1, CEN3, and CEN4 and determine the fate of replication forks that encounter the protein-DNA complex at the centromere. We have shown that replication fork pause sites are coincident with each of these centromeres and therefore probably with all yeast centromeres. We have analyzed the replication of plasmids containing mutant derivatives of CEN3 to determine whether the replication fork pause site is a result of an unusual structure adopted by centromere DNA or a result of the protein-DNA complex formed at the centromere. The mutant centromere derivatives varied in function as well as the ability to form the nuclease-resistant core structure. The data obtained from analysis of these derivatives indicate that the ability to cause replication forks to pause correlates with the ability to form the nuclease-resistant core structure and not with the presence or absence of a particular DNA sequence. Our findings further suggest that the centromere protein-DNA complex is present during S phase when replication forks encounter the centromere and therefore may be present throughout the cell cycle.
Mol Cell Biol 1992 Sep
PMID:Replication forks pause at yeast centromeres. 150 2

Molecular karyotypes of the UC, LEM87 and LEM115 Leishmania tarentolae strains were obtained. All strains had 24-28 chromosomal bands which varied in size between 300 kb and 2.9 Mb. Several recurrent chromosomal polymorphisms occurred in LEM115 after nutrient shock or subcloning. One type of polymorphism involves the truncation of a 365-kb chromosome which contains the miniexon genes. This specific chromosome breakage appears to be induced by the nutrient shock or subcloning process and also occurs spontaneously during routine passage. Another polymorphism is the appearance of a 90-kb minichromosome (115-SNA1) after severe nutrient shock. This appears to be selection of a pre-existing cell type from a mosaic population. The 115-SNA1 minichromosome has sequence homology with a minichromosome in LEM87 cells but shows no homology with any chromosomes in 115wt or other strains. The copy number of 115-SNA1 varies with culture conditions, suggesting a relaxed centromeric control. The nature and origin of this minichromosome is not known.
Mol Biochem Parasitol 1992 Jan
PMID:Recurrent polymorphisms in small chromosomes of Leishmania tarentolae after nutrient stress or subcloning. 154 6


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