Metabolism of Storage Lipids and the Role of Lipid Droplets in the Yeast Schizosaccharomyces pombe

Storage lipids, triacylglycerols (TAG), and steryl esters (SE), are predominant constituents of lipid droplets (LD) in fungi. In several yeast species, metabolism of TAG and SE is linked to various cellular processes, including cell division, sporulation, apoptosis, response to stress, and lipotoxicity. In addition, TAG are an important source for the generation of value-added lipids for industrial and biomedical applications. The fission yeast Schizosaccharomyces pombe is a widely used unicellular eukaryotic model organism. It is a powerful tractable system used to study various aspects of eukaryotic cellular and molecular biology. However, the knowledge of S. pombe neutral lipids metabolism is quite limited. In this review, we summarize and discuss the current knowledge of the homeostasis of storage lipids and of the role of LD in the fission yeast S. pombe with the aim to stimulate research of lipid metabolism and its connection with other essential cellular processes. We also discuss the advantages and disadvantages of fission yeast in lipid biotechnology and recent achievements in the use of S. pombe in the biotechnological production of valuable lipid compounds.     

Yeast sequencing reports. Isolation and sequence analysis of a gene from the linear DNA plasmid pPAC1–2 of Pichia acaciae that shows similarity to a killer toxin gene of Kluyveromyces lactis

The toxin-encoding linear plasmid systems found in Pichia acaciae and Kluyveromyces lactis yeasts appear to be quite similar, both in function and structural organization. By Southern hybridization, a linear plasmid of P. acaciae, pPac1–2, was found to hybridize to the second open reading frame (ORF2) of K. lactis plasmid pGKL1, known to encode the α and β subunits of the K. lactis toxin. A 1·7 kbp segment of pPac1–2 DNA was cloned, sequenced and shown to contain four regions of strong homology to four similarly oriented regions of K. lactis ORF2. This 1·7 kbp fragment also contained an ORF of 1473 bp that could encode a protein of ～ 55·8 kDa. Like the α subunit gene of K. lactis ORF2, a very hydrophobic region occurs at the N-terminus, perhaps representing a signal sequence for transport out of the cell. Unlike K. lactis ORF2, however, the encoded polypeptide is much smaller and lacks a recognizable domain common to chitinases. The structure of a toxin that includes the translation product of this P. acaciae ORF would likely be quite different from that of the K. lactis toxin. Analysis of the upstream region of the P. acaciae ORF revealed an upstream conserved sequence identical to that found before ORFs 8 and 9 of pGKL2. A possible hairpin loop structure, as has been described for each of the four K. lactis pGKL1 ORFs, was found just upstream of the presumed start codon. The similarity of the promoter-like elements found in the linear plasmid genes of these diverse yeasts reinforces the idea of the existence of a unique, but highly conserved, expression system for these novel plasmids. The sequence has been deposited in the GenBank data library under Accession Number U02596.     

The complete sequence of a 10.8 kb segment distal of SUF2 on the right arm of chromosome III from Saccharomyces cerevisiae reveals seven open reading frames including the RVS161, ADP1 and PGK genes.

We have entirely sequenced a 10,835 bp segment of the right arm from chromosome III contained in the J11D and J11D-K3B GF clones. The segment contains seven open reading frames longer then 100 amino acids. Three of them, RVS161 (Urdaci et al., 1990; Crouzet et al., 1991), ADP1 (Purnelle et al., 1991) and PGK1 (Hitzeman et al., 1982) have been described previously. YCR10C encodes a putative membrane protein. YCR8W (encoding a putative protein kinase) and YCR14C extend inside the D10H (Skala et al., 1991) and 62B5-2D clones respectively. Four ARS elements previously reported by Palzkill et al. (1986) are located between RVS161 and YCR10C.     

甘蔗糖蜜生产核苷酸的分离方法研究

本文介绍了利用离子交换层析技术分离甘蔗糖蜜生产的核苷酸之现实性与可行性。探讨了分离核苷酸的最佳工艺条件。     

Molecular interaction networks in the analyses of sequence variation and proteomics data

Protein–protein interaction networks are typically generated in standard cell lines or model organisms as it is prohibitively difficult to record large interaction datasets from specific tissues or disease models at a reasonable pace. Although the interaction data are of high confidence, they thus do not reflect in vivo relationships as such. A wealth of physiologically relevant protein information, obtained under different conditions and from different systems, is available including information on genetic variation, protein levels, and PTMs. However, these data are difficult to assess comprehensively because the relationships between the entities remain elusive from the measurements. Here, we exemplarily highlight recent studies that gained deeper insight from genetic variation, protein, and PTM measurements using interaction information pointing toward the importance and potential of interaction networks for the interpretation of sequencing and proteomics data.     

~(12)C离子束辐照对酵母发酵能力的影响

利用100MeV/u的12C6+离子束辐照酵母Saccharomyces cerevsiea YY,选育出一株高产突变菌株C03A,考察C03A发酵过程中不同温度、pH、糖汁浓度对发酵的影响。通过正交实验确定最佳发酵条件为:糖汁浓度24%、温度35℃、pH5.0。在10L发酵罐实验中,C03A发酵速率相对原始菌株高,36h发酵完全,比原始菌株缩短12h;发酵产酒率达到13.2%(V/V),比原始菌株高1.6%(V/V)。     

西南菌种站部分酿酒增香酵母产酯性能初探

酯类是白酒中的主要香气成分,本文主要介绍西南菌种站保存的部分酿酒增香酵母在不同发酵培养条件下的产酯能力。试验对7株产酯酵母进行3种培养基、3种培养时间的多配方处理发酵,采用皂化法测定总酯。实验结果表明,菌株SICC 2．644与SICC2．645产酯水平较高,分别达到230．2mg／100mL和171．2mg／100mL;大部分菌株于麦芽汁发酵培养能获得较为理想的产酯测试效果。     

Pulsatile Jet Cleaning of Filter Cloths Contaminated with Yeast Cells

The cleaning of filter cloths is necessary to avoid prolonged system downtime and strong fouling. Reliable cleaning concepts are central to the removal of residues from the complex surface of filter cloths. Particle residues, in particular, play a decisive role in the sufficiency of the cleaning performance. Consequently, enhanced particle‐removal cleaning concepts based on pulsatile jets for filter cloths have been developed. By varying the cleaning parameters, it has been demonstrated that increased pulse numbers and velocities improve the cleaning performance. Furthermore, this promising cleaning concept cleaned more effectively than conventional methods. The reduction in the amount of detergent needed is an ecological and economic advantage of pulsatile cleaning.     

The Yeast ATF1 Acetyltransferase Efficiently Acetylates Insect Pheromone Alcohols: Implications for the Biological Production of Moth Pheromones

Many moth pheromones are composed of mixtures of acetates of long‐chain (≥10 carbon) fatty alcohols. Moth pheromone precursors such as fatty acids and fatty alcohols can be produced in yeast by the heterologous expression of genes involved in insect pheromone production. Acetyltransferases that subsequently catalyze the formation of acetates by transfer of the acetate unit from acetyl‐CoA to a fatty alcohol have been postulated in pheromone biosynthesis. However, so far no fatty alcohol acetyltransferases responsible for the production of straight chain alkyl acetate pheromone components in insects have been identified. In search for a non‐insect acetyltransferase alternative, we expressed a plant‐derived diacylglycerol acetyltransferase (EaDAcT) (EC 2.3.1.20) cloned from the seed of the burning bush (Euonymus alatus) in a yeast system. EaDAcT transformed various fatty alcohol insect pheromone precursors into acetates but we also found high background acetylation activities. Only one enzyme in yeast was shown to be responsible for the majority of that background activity, the acetyltransferase ATF1 (EC 2.3.1.84). We further investigated the usefulness of ATF1 for the conversion of moth pheromone alcohols into acetates in comparison with EaDAcT. Overexpression of ATF1 revealed that it was capable of acetylating these fatty alcohols with chain lengths from 10 to 18 carbons with up to 27‐ and 10‐fold higher in vivo and in vitro efficiency, respectively, compared to EaDAcT. The ATF1 enzyme thus has the potential to serve as the missing enzyme in the reconstruction of the biosynthetic pathway of insect acetate pheromones from precursor fatty acids in yeast.