A 7.24 kb genomic DNA fragment from the yeast Saccharomyces cerevisiae chromosome XVI was isolated by complementation of a new temperature-sensitive mutation tsa1. We determined the nucleotide sequence of this fragment located on the right arm of chromosome XVI. Among the three, complete open reading frames: YPR041w, YPR042c and YPR043w contained within this fragment, the gene YPR041w was shown to complement the tsa1 mutation and to correspond to the TIF5 gene encoding an essential protein synthesis initiation translation factor. The YPR042c gene encodes a hypothetical protein of 1075 amino acids containing four putative transmembrane segments and is non-essential for growth. The gene YPR043c encoding the 10 kDa product, highly similar to the human protein L37a from the 60S ribosomal subunit, was found to be essential and a dominant lethal. We conclude that three tightly linked yeast genes are involved in the translation process.

Blue rubber bleb nevus syndrome (BRBNS) is a rare systemic syndrome characterized by venous malformations usually found in the skin and visceral organs. To date, 11 case reports describing BRBNS during pregnancy have been published. To our knowledge, this is the first report describing intracranial, airway, epidural, and birth canal involvement of venous malformations in the same parturient. Key lessons learned include clinical presentation, workup, team management, and care of obstetric patients with this disorder.

This directory was made possible by a unique international collaboration between the 633 scientists whose names appear below. It represents both the first published description of the complete sequence of most chromsomes from Saccharomyces cerevisiae , and the first published overview of the entire sequence. As such, the authors would like future papers referring to the entire sequence and/or its contents to cite this directory; future papers referring to the sequence of individual chromosomes should refer to the papers listed at the head of page 9. The authors’ affiliations appear in the papers describing the individual chromosomes.

In S.cerevisiae, gamma-aminobutyrate (GABA) induces transcription of the UGA genes required for its utilization as a nitrogen source, Analysis of the 5' region of the UGA1 and UGA4 genes led to the identification of a conserved GC-rich sequence (UAS(GABA)) essential to induction by gamma-aminobutyrate, Alone, this UAS(GABA) element also supported some levels of reporter gene transcription in the presence of gamma-aminobutyrate. To be effective, UAS(GABA) requires two positive-acting proteins that both contain a Cys(6)-Zn-2 type zinc-finger motif, namely pathway-specific Uga3p and pleiotropic Uga35p(DaIn81p/DurLp). Further analysis of the UGA4 gene revealed that Gln3p, a global nitrogen regulatory protein containing a GATA zinc-finger domain, is required in order to reach high levels of gamma-aminobutyrate-induced transcription, The Gln3p factor exerts its function mainly through a cluster of 5'-GAT(A/T) A-3'(UAS(GATA)) situated just upstream from UAS(GABA) The role of Gln3p is less predominant in UGA1 than in UGA4 gene expression. We propose that tight coupling between the UAS(GABA) and UAS(GATA) elements enables the cell to integrate, according to its nitrogen status, the induced expression levels of UGA4.

Transport of 4-aminobutyric acid (GABA) in Saccharomyces cerevisiae is mediated by three transport systems: the general amino acid permease (GAP1 gene), the proline permease (PUT4 gene), and a specific GABA permease (UGA4 gene) which is induced in the presence of GABA. The UGA4 gene encoding the inducible GABA-specific transporter was cloned and sequenced and its expression analyzed. The predicted amino acid sequence shows that UGA4 encodes a 62 kDa protein having 9-12 putative membrane-spanning regions. The predicted UGA4 protein shares significant sequence similarity with the yeast choline transporter (CTR gene), exhibiting but limited similarity to the previously reported GABA transporters, i.e. the yeast GAP1 and PUT4 permeases and the rat brain GAT-1 transporter. Induction of UGA4 in the presence of GABA is exerted at the level of UGA4 mRNA accumulation, most probably at the level of transcription itself. This induction is conferred by the 5' flanking region and requires the integrity of two positive regulatory proteins, the inducer-specific factor UGA3 and the pleiotropic factor UGA35/DURL/DAL81. In the absence of the pleiotropic UGA43/DAL80 repressor, UGA4 is constitutively expressed at high level.

The UGA43 gene of Saccharomyces cerevisiae is required for repression of inducible genes involved in the utilization of 4-aminobutyric acid (GABA) or urea as nitrogen sources. The UGA43 gene has been cloned by complementation of a uga43 mutation. The N-terminal region of the UGA43 protein is very similar to the DNA-binding zinc-finger region typical of the GATA regulatory factor family in vertebrates. UGA43 is the first reported instance of a GATA protein with a negative regulatory function. The C-terminal region of the predicted UGA43 protein contains a putative leucine zipper. Sequencing of three uga43 mutant alleles suggests that the GATA and putative leucine-zipper regions are both required for the repressive activity of UGA43. UGA43 appears to be a highly regulated gene. On "poor" nitrogen sources, UGA43 transcripts are measured at high levels whereas they are nearly undetectable in conditions of nitrogen catabolite repression. The levels measured on "poor" nitrogen sources are further increased in uga43 mutant cells, suggesting that UGA43 exerts negative autoregulation.

This chapter focuses on the molecular aspects of amino acid transport and its regulation in Saccharomyces cerevisiae. A distinctive feature of the genus, Saccharomyces, as compared to other yeasts is its inability to use nitrate or nitrite as the sole nitrogen source. In Saccharomyces cerevisiae, the plasma membrane is not freely permeable to nitrogenous compounds, such as amino acids. Therefore, the first step in their utilization is their catalyzed transport across the plasma membrane. Most of the transported amino acids are accumulated inside the yeast cells against a concentration gradient. When amino acids are to be used as a general source of nitrogen, this concentration is crucial because most enzymes that catalyze the first step of catabolic pathways have a low affinity for their substrates. A large number of amino acid transporters have been detected by isolating mutations, which selectively inactivate one permease without altering enzyme activities involving the corresponding amino acid. In addition, competitive inhibition, kinetics, and regulatory behavior have been used as criteria to distinguish one transport system from another.

In the yeast Saccharomyces cerevisiae, induction of the 4-aminobutyrate-catabolic pathway by 4-aminobutyrate requires two positive regulatory factors, encoded by the UGA3 and the UGA35 genes respectively. In addition to this, expression of one gene of this pathway, namely the UGA4 gene encoding the 4-aminobutyrate-specific permease, is controlled negatively by the product of the UGA43 gene [Vissers, S., André, B., Muyldermans, F. & Grenson, M. (1989) Eur. J. Biochem. 181, 357-361]. We show here that the products of two of these regulatory genes, UGA35 and UGA43, also control the expression of the genes encoding the urea-catabolic pathway, although the 4-aminobutyrate and urea-catabolic pathways are synthesised under specific conditions and do not share any enzymatic step or metabolite: the UGA35 pathways are synthesised under specific conditions and do not share any enzymatic step or metabolite: the UGA35 gene is shown to be identical to the DURL gene which was previously identified as a positive regulatory factor of the urea-catabolic pathway; the UGA43 gene product is shown to behave like a negative regulatory factor of this pathway. In contrast to UGA35/DURL and UGA43, the positive regulatory factors encoded by the UGA3 gene and the previously identified DURM gene specifically control 4-aminobutyrate and urea catabolisms respectively. Northern hybridization experiments suggest that the UGA35/DURL and UGA43 common regulatory factors act at the transcriptional level. Our results show that the expression of two biochemically distinct nitrogenous catabolisms, as triggered by their respective inducers, seems to involve multiple regulatory factors, some of which are common to the two catabolic pathways.

The NPR1 gene of Saccharomyces cerevisiae plays a central role in controlling permease activity; its product is required to promote the activity of at least six distinct transport systems for nitrogenous nutrients under conditions of nitrogen catabolite derepression. We report here the nucleotide sequence of the cloned NPR1 gene. The predicted amino acid sequence indicates that NPR1 encodes a protein of 86 kDa which appears to be organized into two distinct structural domains. The amino-terminal domain of NPR1 (residues 1 to 440) contains 26% serine residues and several regions strongly enriched for PEST residues suggesting a short half-life for the NPR1 protein. The carboxy-terminal region of NPR1 contains consensus sequences characteristic of the catalytic domains of protein kinases. Therefore, NPR1-dependent positive control of nitrogen transport systems most likely involves protein phosphorylation. Northern analysis indicates that the absence of general amino acid permease (GAP1) activity in npr1 mutants is not due to reduction in transcription or messenger stability. Hence, the NPR1 protein probably acts at the post-transcriptional level. Proteins that may serve as substrates for phosphorylation are discussed.

In Saccharomyces cerevisiae, mutations at the GAP1 locus selectively abolish the activity of the general amino acid transport system. This permease catalyses active transport of apparently all biological amino acids across the plasma membrane. We have determined the nucleotide sequence of the GAP1 gene. The sequence contains an open reading frame of 601 codons corresponding to a polypeptide of Mr 65578. This polypeptide is strongly hydrophobic; it exhibits three potential glycosylation sites. Hydropathy analysis suggests 12 membrane-spanning regions. The N-terminal domain is charged, it does not resemble hydrophobic signal sequences found in secreted proteins. Hence the GAP1 gene encodes a protein with characteristics typical of integral membrane proteins translocating ligants across cellular membranes. The deduced amino acid sequence of GAP1 protein presents strong similarities to those of the yeast arginine, histidine and proline permeases, suggesting a common evolutionary origin for these amino acid permeases. Nitrogen-source regulation of the GAP1 permease is believed to occur at two distinct levels, i.e. permease synthesis and permease activity [Grenson (1983) Eur. J. Biochem. 133, 135-139]. Northern analysis of GAP1-specific transcripts in wild-type and in mutant strains is in agreement with these views and indicates that nitrogen catabolite repression of GAP1 synthesis occurs at the RNA level.

A. Congres multidisciplinaire « THE RECEPTORS »The induction of the 4-aminobutyric-acid (GABA)-specific permease (UGA4 gene), the GABA transaminase (UGA1 gene), and the succinic-semialdehyde dehydrogenase (UGA2 gene) by GABA requires the integrity of a positive control element encoded by the UGA3 gene (Ramos et al., 1985). A second regulatory element, encoded by the UGA43 gene, has been recently identified. It behaves like a trans-acting negative control element of the UGA4 permease gene expression (Vissers et al., 1989).