María Angeles Freire-Picos

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Codon usage (CU) in Kluyveromyces lactis has been studied. Comparison of CU in highly and lowly expressed genes reveals the existence of 21 optimal codons; 18 of them are also optimal in other yeasts like Saccharomyces cerevisiae or Candida albicans. Codon bias index (CBI) values have been recalculated with reference to the assignment of optimal codons in(More)
The ssu71 alleles of the TFG1 gene, which encodes the largest subunit of TFIIF, were isolated as suppressors of a TFIIB defect that affects the accuracy of transcription start site selection in the yeast Saccharomyces cerevisiae. Here we report that ssu71-1 also suppresses the cell growth and start site defects associated with an altered form of the Rpb1(More)
Heme is of great importance in oxygen-dependent biological functions, since it serves as a prosthetic group for many proteins related to oxygen-binding, oxidative damage prevention and electron transport. It also regulates gene expression through the action of specific transcriptional regulatory factors. In this paper, we present an analysis of(More)
The enzyme 5-aminolaevulinate acid synthase (ALAS) catalyses the first reaction in the haem biosynthetic pathway. In eukaryotes this protein is translated by cytosolic ribosomes and then targeted to the mitochondria. We present evidence that in the yeast Kluyveromyces lactis haem exerts a feedback control upon the import of the ALAS into mitochondria. The(More)
Functional analysis of the KlCYC1 promoter reveals that sequences located upstream to those already published [Freire-Picos, M. A., Rodríguez-Torres, A. M., Ramil, E., Cerdán, M. E., Breuning, K. D., Hollenberg, C. P. & Zitomer, R. S. (1993) Sequence of a cytochrome c from Kluyveromyces lactis and its upstream region, Yeast 9, 201-204] and extending from(More)
Hap1 and Rox1 are transcriptional regulators that bind regulatory sites in the promoters of oxygen-regulated genes in Saccharomyces cerevisiae. Hap1 is a heme-responsive activator of genes induced in aerobic conditions and Rox1 is a repressor of hypoxic genes in aerobic conditions. We have studied transcriptional regulation of a pool of 203 open reading(More)
KlCYC1 encodes for cytochrome c in the yeast Kluyveromyces lactis and is transcribed in two mRNAs with different 3'-processing points. This is an uncommon transcription mechanism in yeast mRNAs. The 3' sequence encompassing the whole region that is needed to produce both mRNAs is analysed. We have determined identical processing points in K.lactis and in(More)
The general repression complex, constituted by the yeast Tup1 and Ssn6 factors, is a conserved global regulator of transcription in eukaryotes. In the yeast Saccharomyces cerevisiae, it is an important repressor of hypoxic genes, such as ANB1, under aerobic conditions and deletion of the TUP1 gene causes a flocculation phenotype. The KlTUP1 gene from the(More)
The Kluyveromyces lactis HIS4 gene (KlHIS4) is transcriptionally regulated by the carbon source. The promoter region encompassing positions −238 to −139 is responsible for this regulation according to lacZ reporter assays. Electrophoretic Mobility Shift Assay (EMSA) experiments on KlHIS4 promoter (positions −218 to −213, Fragment 6, F6) show a specific(More)