scholarly journals Chromatin Assembly Factor I

2020 ◽  
Author(s):  
Genomics ◽  
1996 ◽  
Vol 34 (1) ◽  
pp. 148-150 ◽  
Author(s):  
D.K. Shea ◽  
M. Rutter ◽  
D. Lucente ◽  
M.K. McCormick

2001 ◽  
Vol 21 (5) ◽  
pp. 1784-1794 ◽  
Author(s):  
Stephen D. Johnston ◽  
Shinichiro Enomoto ◽  
Lisa Schneper ◽  
Mark C. McClellan ◽  
Florence Twu ◽  
...  

ABSTRACT Cac3p/Msi1p, the Saccharomyces cerevisiae homolog of retinoblastoma-associated protein 48 (RbAp48), is a component of chromatin assembly factor I (CAF-I), a complex that assembles histones H3 and H4 onto replicated DNA. CAC3 overexpression also suppresses the RAS/cyclic AMP (cAMP) signal transduction pathway by an unknown mechanism. We investigated this mechanism and found that CAC3 suppression of RAS/cAMP signal transduction was independent of either CAC1 orCAC2, subunits required for CAF-I function.CAC3 suppression was also independent of other chromatin-modifying activities, indicating that Cac3p has at least two distinct, separable functions, one in chromatin assembly and one in regulating RAS function. Unlike Cac1p, which localizes primarily to the nucleus, Cac3p localizes to both the nucleus and the cytoplasm. In addition, Cac3p associates with Npr1p, a cytoplasmic kinase that stablizes several nutrient transporters by antagonizing a ubiquitin-mediated protein degradation pathway. Deletion ofNPR1, like overexpression of Cac3p, suppressed theRAS/cAMP pathway. Furthermore, NPR1overexpression interfered with the ability of CAC3 to suppress the RAS/cAMP pathway, indicating that extra Cac3p suppresses the RAS/cAMP pathway by sequestering Npr1p. Deletion of NPR1 did not affect the quantity, phosphorylation state, or localization of Ras2p. Consistent with the idea that Npr1p exerts its effect on the RAS/cAMP pathway by antagonizing a ubiquitin-mediated process, excess ubiquitin suppressed both the heat shock sensitivity and the sporulation defects caused by constitutive activation of the RAS/cAMP pathway. Thus, CAC3/MSI1 regulates the RAS/cAMP pathway via a chromatin-independent mechanism that involves the sequestration of Npr1p and may be due to the increased ubiquitination of an Npr1p substrate.


1997 ◽  
Vol 11 (3) ◽  
pp. 358-370 ◽  
Author(s):  
S Enomoto ◽  
P D McCune-Zierath ◽  
M Gerami-Nejad ◽  
M A Sanders ◽  
J Berman

Genetics ◽  
1999 ◽  
Vol 151 (2) ◽  
pp. 485-497 ◽  
Author(s):  
John C Game ◽  
Paul D Kaufman

Abstract In vitro, the protein complex Chromatin Assembly Factor-I (CAF-I) from human or yeast cells deposits histones onto DNA templates after replication. In Saccharomyces cerevisiae, the CAC1, CAC2, and CAC3 genes encode the three CAF-I subunits. Deletion of any of the three CAC genes reduces telomeric gene silencing and confers an increase in sensitivity to killing by ultraviolet (UV) radiation. We used double and triple mutants involving cac1Δ and yeast repair gene mutations to show that deletion of the CAC1 gene increases the UV sensitivity of cells mutant in genes from each of the known DNA repair epistasis groups. For example, double mutants involving cac1Δ and excision repair gene deletions rad1Δ or rad14Δ showed increased UV sensitivity, as did double mutants involving cac1Δ and deletions of members of the RAD51 recombinational repair group. cac1Δ also increased the UV sensitivity of strains with defects in either the error-prone (rev3Δ) or error-free (pol30-46) branches of RAD6-mediated postreplicative DNA repair but did not substantially increase the sensitivity of strains carrying null mutations in the RAD6 or RAD18 genes. Deletion of CAC1 also increased the UV sensitivity and rate of UV-induced mutagenesis in rad5Δ mutants, as has been observed for mutants defective in error-free postreplicative repair. Together, these data suggest that CAF-I has a role in error-free postreplicative damage repair and may also have an auxiliary role in other repair mechanisms. Like the CAC genes, RAD6 is also required for gene silencing at telomeres. We find an increased loss of telomeric gene silencing in rad6Δ cac1Δ and rad18Δ cac1Δ double mutants, suggesting that CAF-I and multiple factors in the postreplicative repair pathway influence chromosome structure.


Nucleus ◽  
2016 ◽  
Vol 7 (4) ◽  
pp. 405-414 ◽  
Author(s):  
Brandon Wyse ◽  
Roxanne Oshidari ◽  
Hollie Rowlands ◽  
Sanna Abbasi ◽  
Krassimir Yankulov

1998 ◽  
Vol 18 (8) ◽  
pp. 4793-4806 ◽  
Author(s):  
Paul D. Kaufman ◽  
Jennifer L. Cohen ◽  
Mary Ann Osley

ABSTRACT Chromatin assembly factor I (CAF-I) is a three-subunit histone-binding complex conserved from the yeast Saccharomyces cerevisiae to humans. Yeast cells lacking CAF-I (cacΔ mutants) have defects in heterochromatic gene silencing. In this study, we showed that deletion of HIRgenes, which regulate histone gene expression, synergistically reduced gene silencing at telomeres and at the HM loci incacΔ mutants, although hirΔ mutants had no silencing defects when CAF-I was intact. Therefore, Hir proteins are required for an alternative silencing pathway that becomes important in the absence of CAF-I. Because Hir proteins regulate expression of histone genes, we tested the effects of histone gene deletion and overexpression on telomeric silencing and found that alterations in histone H3 and H4 levels or in core histone stoichiometry reduced silencing in cacΔ mutants but not in wild-type cells. We therefore propose that Hir proteins contribute to silencing indirectly via regulation of histone synthesis. However, deletion of combinations of CAC and HIR genes also affected the growth rate and in some cases caused partial temperature sensitivity, suggesting that global aspects of chromosome function may be affected by the loss of members of both gene families.


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