Dictyostelium TRFA Homologous to Yeast Ssn6 Is Required for Normal Growth and Early Development

Saito, Junichi; Kon, Takahide; Nagasaki, Akira; Adachi, Hiroyuki; Sutoh, Kazuo

doi:10.1074/jbc.273.38.24654

Cited by 4 publications

(3 citation statements)

References 45 publications

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“…1A). A blastp search (Altschul et al ., 1990) against protein sequences in the database revealed the presence of a domain also found in Ssn6p from S. cerevisiae (Trumbly, 1988; Schultz et al ., 1990), a hypothetical protein in Schizosaccharomyces pombe (GenBank accession number ) and TRFA from Dictyostelium discoideum (Saito et al ., 1998). Within this region of about 352 amino acids, the four proteins share 47% amino acid identity, with the S. pombe domain being most closely related to the respective Sql1 domain (74% amino acid identity).…”

Section: Resultsmentioning

confidence: 99%

A homologue of the transcriptional repressor Ssn6p antagonizes cAMP signalling in Ustilago maydis

Loubradou¹,

Brachmann

Feldbrügge³

et al. 2001

Molecular Microbiology

129

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SummaryIn Ustilago maydis, cAMP signalling is crucial for successful infection of maize plants. Strains are nonpathogenic if mutated in any of the currently identified components of this signalling pathway, such as the a-subunit of a heterotrimeric G protein Gpa3, the adenylate cyclase Uac1 and the regulatory and catalytic subunit of protein kinase A Ubc1 and Adr1 respectively. Deletion of gpa3, uac1 or adr1 triggers filamentous growth, and certain point mutations in gpa3 and ubc1 that mimic a high cAMP level display a glossy colony phenotype. Screening an autonomously replicating U. maydis library in such a background (gpa3 Q206L ), we identified sql1 as a suppressor of the glossy colony phenotype. Interestingly, only alleles carrying C-terminal truncations of Sql1 were able to complement the mutant phenotype, suggesting a gain-of-function by these variants. Sql1 is a functional homologue of the yeast transcriptional repressor Ssn6p and contains 10 tetratricopeptide repeats (TPRs), of which the first six are important for suppressor function. Truncated sql1 alleles that suppress the glossy colony phenotype of gpa3 Q206L strains induce filamentous growth when introduced in wild type. Filamentation of these strains is reversed in the presence of cAMP. We present a model in which Sql1 is part of an evolutionary conserved Sql1±Tup1 transcriptional repressor complex that antagonizes cAMP signalling by repressing cAMP-regulated genes.

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Section: Resultsmentioning

confidence: 99%

A homologue of the transcriptional repressor Ssn6p antagonizes cAMP signalling in Ustilago maydis

Loubradou¹,

Brachmann

Feldbrügge³

et al. 2001

Molecular Microbiology

129

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“…For the selection and maintenance of transformants, blasticidin S and/or G418 were used at a ®nal concentration of 10 mg/mL. REMI mutagenesis and selections of aggregation-de®cient mutants were performed exactly as described previously (Adachi et al 1994;Adachi et al 1997;Nagasaki et al 1998;Saito et al 1998). For development in liquid suspension, vegetative cells were harvested from axenic cultures at a cell density of 2,3´10 6 cells/mL.…”

Section: Cell Culture and Developmentmentioning

confidence: 99%

amiB, a novel gene required for the growth/differentiation transition in Dictyostelium

2000

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Background: The differentiation programme of Dictyostelium discoideum is initiated by starvation. Nutrient depletion triggers the differentiation of Dictyostelium cells through the transcriptional inactivation of some growth-phase genes, as well as through the transcriptional activation of essential genes required for the aggregation of the cells. The adenylyl cyclase (ACA) gene, acaA, is one of the earliest genes expressed following starvation. ACA produces intracellular and extracellular cAMP that drives further differentiation by inducing chemotaxis, developmental gene expression and morphogenesis of Dictyostelium cells. Although several genes have been identi®ed as being essential for the initiation of differentiation process, such as the transcriptional activation of ACA expression, the molecular mechanisms of the growth/differentiation transition remain to be explored.

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“…The Ssn6 protein is characterized by a central 10-copy tetratricopeptide repeat domain, which provides a protein interaction surface that mediates the interaction with Tup1 (41,43) as well as recruitment of the complex to target genes by different DNA-bound repressor proteins (26,47). The different tetratricopeptide repeat motifs play an important role in the specificity of Ssn6 interaction with different repressor proteins (44,46).…”

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confidence: 99%

Individual Subunits of the Ssn6-Tup11/12 Corepressor Are Selectively Required for Repression of Different Target Genes

Fagerström‐Billai

Durand-Dubief

Ekwall

et al. 2007

Molecular and Cellular Biology

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The Saccharomyces cerevisiae Ssn6 and Tup1 proteins form a corepressor complex that is recruited to target genes by DNA-bound repressor proteins. Repression occurs via several mechanisms, including interaction with hypoacetylated N termini of histones, recruitment of histone deacetylases (HDACs), and interactions with the RNA polymerase II holoenzyme. The distantly related fission yeast, Schizosaccharomyces pombe, has two partially redundant Tup1-like proteins that are dispensable during normal growth. In contrast, we show that Ssn6 is an essential protein in S. pombe, suggesting a function that is independent of Tup11 and Tup12. Consistently, the group of genes that requires Ssn6 for their regulation overlaps but is distinct from the group of genes that depend on Tup11 or Tup12. Global chip-on-chip analysis shows that Ssn6 is almost invariably found in the same genomic locations as Tup11 and/or Tup12. All three corepressor subunits are generally bound to genes that are selectively regulated by Ssn6 or Tup11/12, and thus, the subunit specificity is probably manifested in the context of a corepressor complex containing all three subunits. The corepressor binds to both the intergenic and coding regions of genes, but differential localization of the corepressor within genes does not appear to account for the selective dependence of target genes on the Ssn6 or Tup11/12 subunits. Ssn6, Tup11, and Tup12 are preferentially found at genomic locations at which histones are deacetylated, primarily by the Clr6 class I HDAC. Clr6 is also important for the repression of corepressor target genes. Interestingly, a subset of corepressor target genes, including direct target genes affected by Ssn6 overexpression, is associated with the function of class II (Clr3) and III (Hst4 and Sir2) HDACs.

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Dictyostelium TRFA Homologous to Yeast Ssn6 Is Required for Normal Growth and Early Development

Cited by 4 publications

References 45 publications

A homologue of the transcriptional repressor Ssn6p antagonizes cAMP signalling in Ustilago maydis

A homologue of the transcriptional repressor Ssn6p antagonizes cAMP signalling in Ustilago maydis

amiB, a novel gene required for the growth/differentiation transition in Dictyostelium

Individual Subunits of the Ssn6-Tup11/12 Corepressor Are Selectively Required for Repression of Different Target Genes

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