Identification and characterization of regulatory elements in the phosphoenolpyruvate carboxykinase gene PCK1 of Saccharomyces cerevisiae

Phosphoenolpyruvate carboxykinase is a key enzyme in gluconeogenesis. The expression of the PCK1 gene in Saccharomyces cerevisiae is strictly regulated and dependent on the carbon source provided. Two upstream activation sites (UAS1_PCK1 and UAS2_PCK1) and one upstream repression site (URS_PCK1) were localized by detailed deletion analysis. The efficacy of these three promoter elements when separated from each other was confirmed by investigations using heterologous promoter test plasmids. Activation mediated by UAS1_PCK1 or UAS2_PCK1 did not occur in the presence of glucose, indicating that these elements are essential for glucose derepression. The repressing effect caused by URS_PCK1 was much stronger in glucose-grown cells than in ethanol-grown cells.     

Asymmetric DNA bending induced by the yeast multifunctional factor TUF

TUF is a yeast regulatory factor that binds to conserved DNA sequence elements involved in gene activation or silencing as well as in telomere function. Using gel electrophoresis analyses, we show here that TUF induces DNA bending at a site located upstream of the recognition sequence (rpg box). Several point mutations in the rpg box reduced TUF binding strength without affecting the extent of bending. Selective proteolysis of TUF.DNA complexes further suggested the existence of two separate protein domains involved in DNA bending and specific DNA recognition. DNA bending may be an important feature of multifunctional factors that could help them to recruit other proteins for the formation of multiprotein complexes.     

Sequence and promoter analysis of the highly expressed TEF gene of the filamentous fungus Ashbya gossypii

Ashbya gossypii carries only a single gene (TEF) coding for the abundant translation elongation factor 1. Cloning and sequencing of this gene and deletion analysis of the promoter region revealed an extremely high degree of similarity with the well studied TEF genes of the yeast Saccharomyces cerevisiae including promoter upstream activation sequence (UAS) elements. The open reading frames in both species are 458 codons long and show 88.6% identity at the DNA level and 93.7% identity at the protein level. A short DNA segment in the promoter, between nucleotides -268 and -213 upstream of the ATG start codon, is essential for high-level expression of the A. gossypii TEF gene. It carries two sequences, GCCCATACAT and ATCCATACAT, with high homology to the UAS_rpg sequence of S. cerevisiae, which is an essential promoter element in genes coding for highly expressed components of the translational apparatus. UAS_rpg sequences are binding sites for the S. cerevisiae protein TUF, also called RAP1 or GRF1. In gel retardation with A. gossypii protein extracts we demonstrated specific protein binding to the short TEF promoter segment carrying the UAS_rpg homologous sequences.     

The glucose repression and RAS-cAMP signal transduction pathways of Saccharomyces cerevisiae each affect RNA processing and the synthesis of a reporter protein

Previously we reported that mutations in the Saccharomyces cerevisiae REG1 gene encoding a negative regulator of glucose-repressible genes, suppress the RNA processing defects and temperature-sensitive growth of rna1-1 and prp cells. This result and the fact that growth on non-glucose carbon sources also suppresses rna1-1 led us to propose that RNA processing and export of RNA from the nucleus are responsive to carbon source regulation. To understand how carbon source affects these processes, we used p70, an antigen regulated by REGI and by glucose availability, as a reporter. We found that the response of p70 to glucose availability is mediated by both the SNFI-SSN6-dependent glucose repression and the RAS-cAMP pathways. These results led us to test whether the RAS-cAMP pathway interacts with RNA1. We found that suppression of rnal-1 appears to be mediated, at least in part, by the RAS-cAMP pathway.     

牛樟芝倍半萜合酶基因克隆及在不同培养基中的表达

牛樟芝(Antrodia camphorata)是一种珍稀食药用菌,能产生具有抗癌活性的倍半萜类化合物。对牛樟芝基因组进行分析,获得倍半萜合酶基因序列并设计特异引物,提取在Glu培养基(麦芽浸粉6 g/L,酵母提取物3 g/L,葡萄糖40 g/L)上生长的牛樟芝菌丝体的RNA,利用RT-PCR技术克隆得到倍半萜合酶基因AcTPS1。AcTPS1基因c DNA全长为969 bp,编码323个氨基酸,根据系统进化树可知AcTPS1氨基酸序列与其他9种真菌倍半萜合酶聚为一类。AcTPS1拥有典型倍半萜合酶的结构域(RRSRSATAEAYACFIW),之后检测AcTPS1在不同培养基上的菌丝中的表达结果显示不同碳源中,只有葡萄糖作为碳源时该基因表达,不同氮源中,以番茄浸粉和酪蛋白胨为氮源时该基因表达。说明AcTPS1是一类诱导型表达的基因。为利用发酵培养以及异源表达手段获得牛樟芝活性化合物提供参考。     

Regulation of the phosphate regulon of Escherichia coli: Characterization of the promoter of the pstS gene

Summary The pstS gene belongs to the phosphate regulon whose expression is induced by phosphate starvation and regulated positively by the PhoB protein. The phosphate (pho) box is a consensus sequence shared by the regulatory regions of the genes in the pho regulon. We constructed two series of deletion mutations in a plasmid in vitro, with upstream and downstream deletions in the promoter region of pstS, which contains two pho boxes in tandem, and studied their promoter activity by connecting them with a promoterless gene for chloramphenicol acetyltransferase. Deletions extending into the upstream pho box but retaining the downstream pho box greatly reduced promoter activity, but the remaining activity was still regulated by phosphate levels in the medium and by the PhoB protein, indicating that each pho box is functional. No activity was observed in deletion mutants which lacked the remaining pho box or the-10 region. Therefore, the pstS promoter was defined to include the two pho boxes and the-10 region. The PhoB protein binding region in the pstS regulatory region was studied with the deletion plasmids by a gelmobility retardation assay. The results suggest the protein binds to each pho box on the pstS promoter. A phoB deletion mutant was constructed, and we demonstrated that expression of pstS was strictly dependent on the function of the PhoB protein.     

Interactions between the regulatory regions of twoAdh alleles

A region (NS1) that acts like an enhancer is located approximately 300 bp upstream of the larval cap site in theAdh gene ofD. melanogaster. When this sequence is deleted (NS1), the gene fails to express ADH protein. Gene expression can be restored by placing a secondAdh gene with an intact enhancer elsewhere on the same plasmid. In these circumstances, both genes are expressed equally regardless of their orientation on the plasmid. In this report we further characterize the interactions that occur when a single enhancer activates expression from a proximal and distant promoter. We have made the following observations: (1) While the two genes are expressed equivalently, their expression relative to a plasmid carrying two intact genes is reduced by a factor of 2 to 6 depending on the orientation of the two genes. (2) The single enhancer drives expression of both genes on any given plasmid molecule. (3) The enhancer does not interact with theAdh gene from which the NS7 region (which spans the larval TATA box) is removed. (4) Expression of the NS1 gene can be restored by an intact gene when both are inserted together into theDrosophila genome via P element-mediated transformation. (5) Increasing the separation between the two genes on a plasmid by up to 15 kbp does not prevent the restoration of expression of the NS1 gene. We propose a model that explains how a single enhancer can stimulate equal expression from two genes.     

Glucose kinase of Streptomyces coelicolor A3(2): large-scale purification and biochemical analysis

Glucose kinase of Streptomyces coelicolor A3(2) is essential for glucose utilisation and is required for carbon catabolite repression (CCR) exerted through glucose and other carbon sources. The protein belongs to the ROK-family, which comprises bacterial sugar kinases and regulators. To better understand glucose kinase function, we have monitored the cellular activity and demonstrated that the choice of carbon sources did not significantly change the synthesis and activity of the enzyme. The DNA sequence of the Streptomyces lividans glucose kinase gene glkA was determined. The predicted gene product of 317 amino acids was found to be identical to S. coelicolor glucose kinase, suggesting a similar role for this protein in both organisms. A procedure was developed to produce pure histidine-tagged glucose kinase with a yield of approximately 10 mg/l culture. The protein was stable for several weeks and was used to raise polyclonal antibodies. Purified glucose kinase was used to explore protein-protein interaction by surface plasmon resonance. The experiments revealed the existence of a binding activity present in S. coelicolor cell extracts. This indicated that glucose kinase may interact with (an)other factor(s), most likely of protein nature. A possible cross-talk with proteins of the phosphotransferase system, which are involved in carbon catabolite repression in other bacteria, was investigated.     

<Emphasis Type="Italic"> Cis</Emphasis>-acting elements sufficient for induction of<Emphasis Type="Italic"> FDH1</Emphasis> expression by formate in the methylotrophic yeast<Emphasis Type="Italic"> Candida boidinii</Emphasis>

The FDH1 gene of Candida boidinii encodes an NAD⁺-dependent formate dehydrogenase, which catalyzes the last reaction in the methanol dissimilation pathway. FDH1 expression is strongly induced by methanol, as are the promoters of the genes AOD1 (alcohol oxidase) and DAS1 (dihydroxyacetone synthase). FDH1 expression can be induced by formate when cells are grown on a medium containing glucose as a carbon source, whereas expression of AOD1 and DAS1 is completely repressed in the presence of glucose. Using deletion analyses, we identified two cis-acting regulatory elements, termed UAS-FM and UAS-M, respectively, in the 5 non-coding region of the FDH1 gene. Both elements were necessary for full induction of the FDH1 promoter by methanol, while only the UAS-FM element was required for full induction by formate. Irrespective of whether induction was achieved with methanol or formate, the UAS-FM element enhanced the level of induction of the FDH1 promoter in a manner dependent on the number of copies, but independent of their orientation, and also converted the ACT1 promoter from a constitutive into an inducible element. Our results not only provide a powerful promoter for heterologous gene expression, but also yield insights into the mechanism of regulation of FDH1 expression at the molecular level.Communicated by C. P. Hollenberg