Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The FHL1 gene was isolated by screening for high-copy-number suppressors of conditional RNA polymerase III mutations. This gene is unique on the yeast genome and was located close to RPC40 and PRE2 on the right arm of chromosome XVI. It codes for a 936-amino-acid protein containing a domain similar to the fork head DNA-binding domain, initially found in the developmental fork head protein of Drosophila melanogaster and in the HNF-3 family of hepatocyte mammalian transcription factors. Null mutations caused a severe reduction in growth rate and a lower rRNA content that resulted from defective rRNA processing. There was no detectable effect on mRNA splicing. Thus, the Fhl1p protein plays a key role in the control of rRNA processing, presumably by acting as a transcriptional regulator of genes specifically involved in that process. Moreover, mutants carrying the RNA polymerase III mutations were slightly defective in rRNA processing. This accounts for the isolation of FHL1 as a dosage-dependent suppressor and suggests that rRNA processing depends on a still-unidentified RNA polymerase III transcript.
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PMID:Suppression of yeast RNA polymerase III mutations by FHL1, a gene coding for a fork head protein involved in rRNA processing. 816 51

NtFHA1 encodes a novel protein containing the forkhead-associated (FHA) domain and the acidic domain in Nicotiana tabacum. NtFHA1 functions as a transactivator and is targeted to the nucleus. The sequence of the FHA domain of NtFHA1 is significantly homologous to that of the Fhl1 forkhead transcription factor of yeast. FHL1 was previously identified as a suppressor of RNA polymerase III mutations, and the fhl1 deletion mutant exhibited severe growth defects and impaired rRNA processing. Ectopic expression of the FHA domain of NtFHA1 (but not its mutant form) resulted in severe growth retardation in yeast. Similarly, expression of Fhl1, its FHA domain, or chimeric Fhl1 containing the NtFHA1 FHA domain also inhibited yeast growth. Yeast cells overexpressing the FHA domains of NtFHA1 and Fhl1 contained lower levels of mature rRNAs and exhibited rRNA-processing defects, similar to the fhl1 null mutant. Chimeric Fhl1 (but not the mutant form with a small deletion in its FHA domain) fully complemented the growth and rRNA-processing defects of the fhl1 null mutant, demonstrating that the FHA domain of NtFHA1 can functionally substitute for the FHA domain of Fhl1. These results demonstrate that the FHA domains of NtFHA1 and Fhl1 are conserved in their structure and function and that the FHA domain of Fhl1 is critically involved in regulation of rRNA processing in yeast. NtFHA1 function in plants may be analogous to Fhl1 function in yeast.
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PMID:Forkhead-associated domains of the tobacco NtFHA1 transcription activator and the yeast Fhl1 forkhead transcription factor are functionally conserved. 1214 45

HMO1 is a high-mobility group B protein that plays a role in transcription of genes encoding rRNA and ribosomal proteins (RPGs) in Saccharomyces cerevisiae. This study uses genome-wide chromatin immunoprecipitation to study the roles of HMO1, FHL1, and RAP1 in transcription of these genes as well as other RNA polymerase II-transcribed genes in yeast. The results show that HMO1 associates with the 35S rRNA gene in an RNA polymerase I-dependent manner and that RPG promoters (138 in total) can be classified into several distinct groups based on HMO1 abundance at the promoter and the HMO1 dependence of FHL1 and/or RAP1 binding to the promoter. FHL1, a key regulator of RPGs, binds to most of the HMO1-enriched and transcriptionally HMO1-dependent RPG promoters in an HMO1-dependent manner, whereas it binds to HMO1-limited RPG promoters in an HMO1-independent manner, irrespective of whether they are transcribed in an HMO1-dependent manner. Reporter gene assays indicate that these functional properties are determined by the promoter sequence.
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PMID:Assembly of regulatory factors on rRNA and ribosomal protein genes in Saccharomyces cerevisiae. 1764 81