Functional differences among the sixSaccharomyces cerevisiae tRNATrp genes

Ong, Weoi-Choo; Ibrahim, Mohammed; Town, Matthew; Johnson, Jerry D.

doi:10.1002/(sici)1097-0061(199711)13:14<1357::aid-yea180>3.0.co;2-3

Cited by 11 publications

(3 citation statements)

References 8 publications

(9 reference statements)

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“…Such informational suppression is well documented (50 -52) and also accounts for the reproducibility of the lag period observed in response to selective pressure ( Fig. 2) (53).…”

Section: Growth Characteristics Of Yeast Coq7 Mutant Strains In Glyc-supporting

confidence: 62%

Demethoxy-Q, An Intermediate of Coenzyme Q Biosynthesis, Fails to Support Respiration in Saccharomyces cerevisiae and Lacks Antioxidant Activity

Padilla

Jonassen

Jiménez-Hidalgo

et al. 2004

Journal of Biological Chemistry

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Caenorhabditis elegans clk-1 mutants cannot produce coenzyme Q 9 and instead accumulate demethoxy-Q 9 (DMQ 9 ). DMQ 9 has been proposed to be responsible for the extended lifespan of clk-1 mutants, theoretically through its enhanced antioxidant properties and its decreased function in respiratory chain electron transport. In the present study, we assess the functional roles of DMQ 6 in the yeast Saccharomyces cerevisiae. Three mutations designed to mirror the clk-1 mutations of C. elegans were introduced into COQ7, the yeast homologue of clk-1: E233K, predicted to disrupt the di-iron carboxylate site considered essential for hydroxylase activity; L237Stop, a deletion of 36 amino acid residues from the carboxyl terminus; and P175Stop, a deletion of the carboxyl-terminal half of Coq7p. Growth on glycerol, quinone content, respiratory function, and response to oxidative stress were analyzed in each of the coq7 mutant strains. Yeast strains lacking Q 6 and producing solely DMQ 6 were respiratory deficient and unable to support either NADH-cytochrome c reductase or succinate-cytochrome c reductase activities. DMQ 6 failed to protect cells against oxidative stress generated by H 2 O 2 or linolenic acid. Thus, in the yeast model system, DMQ does not support respiratory activity and fails to act as an effective antioxidant. These results suggest that the life span extension observed in the C. elegans clk-1 mutants cannot be attributed to the presence of DMQ per se.

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“…Such informational suppression is well documented (50 -52) and also accounts for the reproducibility of the lag period observed in response to selective pressure ( Fig. 2) (53).…”

Section: Growth Characteristics Of Yeast Coq7 Mutant Strains In Glyc-supporting

confidence: 62%

Demethoxy-Q, An Intermediate of Coenzyme Q Biosynthesis, Fails to Support Respiration in Saccharomyces cerevisiae and Lacks Antioxidant Activity

Padilla

Jonassen

Jiménez-Hidalgo

et al. 2004

Journal of Biological Chemistry

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“…This could reflect preferential interaction of TFIIIB with flanking sequences, since TFIIIB creates an extensive footprint on the 5′ flank of tRNA genes (Huibregtse and Engelke, 1989; Kassavetis et al ., 1989). Other studies have demonstrated that different tRNA genes with identical coding sequences are expressed at different levels due to specific upstream elements (Raymond et al ., 1985; Ong et al ., 1997). One study specifically demonstrated that the efficiency of TFIIIB loading varies with the 5′ flanking sequence (Joazeiro et al ., 1996).…”

Section: Discussionmentioning

confidence: 99%

“…It is interesting that only a subset of Pol III transcribed genes function as boundaries, suggesting that there are unique features of this tRNA gene at the HMR locus. The requirement of the flanking sequences for full barrier function is not surprising, as several studies have shown that tRNA flanks contribute to transcriptional potential, even though the promoter elements are within the genes (Sprague et al ., 1980; Dingermann et al ., 1982; Raymond and Johnson, 1983; Shaw and Olson, 1984; Young et al ., 1991; Ong et al ., 1997). This could reflect preferential interaction of TFIIIB with flanking sequences, since TFIIIB creates an extensive footprint on the 5′ flank of tRNA genes (Huibregtse and Engelke, 1989; Kassavetis et al ., 1989).…”

Section: Discussionmentioning

confidence: 99%

RNA polymerase III and RNA polymerase II promoter complexes are heterochromatin barriers in Saccharomyces cerevisiae

2001

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The chromosomes of eukaryotes are organized into structurally and functionally discrete domains. Several DNA elements have been identi®ed that act to separate these chromatin domains. We report a detailed characterization of one of these elements, identifying it as a unique tRNA gene possessing the ability to block the spread of silent chromatin in Saccharomyces cerevisiae ef®ciently. Transcriptional potential of the tRNA gene is critical for barrier activity, as mutations in the tRNA promoter elements, or in extragenic loci that inhibit RNA polymerase III complex assembly, reduce barrier activity. Also, we have reconstituted the Drosophila gypsy element as a heterochromatin barrier in yeast, and have identi®ed other yeast sequences, including the CHA1 upstream activating sequence, that function as barrier elements. Extragenic mutations in the acetyltransferase genes SAS2 and GCN5 also reduce tRNA barrier activity, and tethering of a GAL4/SAS2 fusion creates a robust barrier. We propose that silencing mediated by the Sir proteins competes with barrier element-associated chromatin remodeling activity.

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TFIIIC bound DNA elements in nuclear organization and insulation

Kirkland

Raab

Kamakaka

2013

Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanism

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tRNA genes (tDNAs) have been known to have barrier insulator function in budding yeast, Saccharomyces cerevisiae, for over a decade. tDNAs also play a role in genome organization by clustering at sites in the nucleus and both of these functions are dependent on the transcription factor TFIIIC. More recently TFIIIC bound sites devoid of pol III, termed Extra-TFIIIC sites (ETC) have been identified in budding yeast and these sites also function as insulators and affect genome organization. Subsequent studies in Schizosaccharomyces pombe showed that TFIIIC bound sites were insulators and also functioned as Chromosome Organization Clamps (COC); tethering the sites to the nuclear periphery. Very recently studies have moved to mammalian systems where pol III genes and their associated factors have been investigated in both mouse and human cells. Short Interspersed Nuclear Elements (SINEs) that bind TFIIIC, function as insulator elements and tDNAs can also function as both enhancer -blocking and barrier insulators in these organisms. It was also recently shown that tDNAs cluster with other tDNAs and with ETCs but not with pol II transcribed genes. Intriguingly, TFIIIC is often found near pol II transcription start sites and it remains unclear what the consequences of TFIIIC based genomic organization are and what influence pol III factors have on pol II transcribed genes and vise versa. In this review we provide a comprehensive overview of the known data on pol III factors in insulation and genome organization and identify the many open questions that require further investigation. \

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Functional differences among the sixSaccharomyces cerevisiae tRNATrp genes

Cited by 11 publications

References 8 publications

Demethoxy-Q, An Intermediate of Coenzyme Q Biosynthesis, Fails to Support Respiration in Saccharomyces cerevisiae and Lacks Antioxidant Activity

Demethoxy-Q, An Intermediate of Coenzyme Q Biosynthesis, Fails to Support Respiration in Saccharomyces cerevisiae and Lacks Antioxidant Activity

RNA polymerase III and RNA polymerase II promoter complexes are heterochromatin barriers in Saccharomyces cerevisiae

TFIIIC bound DNA elements in nuclear organization and insulation

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