Evolutionary conservation of the human homologue of the yeast cell cycle control gene cdc2 and assignment of Cd2 to chromosome 10

Summary The human homologue of the fission yeast Schizosaccharomyces pombe cell cycle control gene cdc2 has been assigned to chromosome 10. DNA hybridization reveals that this gene is highly conserved in vertebrates. The human CDC2 gene probe detects a simple two-allele polymorphism in Taq1-digested DNA.     

Molecular organisation of the quinic acid utilization (QUT) gene cluster in Aspergillus nidulans

Summary The functional integrity of the QUTB gene (encoding quinate dehydrogenase) has been confirmed by transformation of a qutB mutant strain. The DNA sequence of the contiguous genes QUTD (quinate permease), QUTB and QUTG (function unknown) has been determined and analysed, together with that of QUTE (catabolic 3-dehydroquinase). The QUTB sequence shows significant homology with the shikimate dehydrogenase function of the complex AROM locus of Aspergillus nidulans, and with the QA-3 quinate dehydrogenase and QA-1S (repressor) genes of Neurospora crassa. The QUTD gene shows strong homology with the N. crassa QA-Y gene and QUTG with the QA-X gene. QUTD, QUTB, and QUTG, QUTE form two pairs of divergently transcribed genes, and conserved sequence motifs identified in the two common 5 non-coding regions show significant homology with UAS _GAL and UAS _QA sequences of the Saccharomyces cerevisiae and N. crassa Gal and QA systems. In addition, conserved 5 sequences homologous to the mammalian CAAT box are noted and a previously unreported conserved 22 nucleotide motif is presented.     

Transport of 6-deoxyglucose in Saccharomyces cerevisiae.

The uptake of 6-deoxyglucose was measured in wild-type Saccharomyces cerevisiae, in a double mutant strain lacking activity for hexokinases A and B (hxkl hxk2), in a triple mutant strain lacking activity for both hexokinases and glucokinase (hxkl hxk2 glk), and in the triple mutant with high levels of activity of single kinases restored by introduction of the cloned genes. In the wild-type strain, uptake of the glucose analog showed two components, with Km values of ca. 20 mM ("high affinity") and 250 mM ("low affinity"), respectively. The double mutant also had high- and low-affinity components, but the triple mutant showed only low-affinity uptake. Reintroduction of the single kinases to the triple mutant restored high-affinity uptake. (Other experiments on 6-deoxyglucose uptake are also presented, including the apparent use of the galactose transport system when induced.) These results show that the recent implication of the kinases in transport of glucose (L.F. Bisson and D.G. Fraenkel, Proc. Natl. Acad. Sci. U.S.A. 80:1730-1734, 1983) applies equally to the nonmetabolized analog 6-deoxyglucose and suggests that the role of the kinases in transport is not merely a consequence of metabolism of the transported compound.     

嗜盐耐盐微生物抗盐胁迫相关离子转运蛋白研究进展

离子转运蛋白在维持细胞内pH稳态、离子动态平衡等方面发挥着重要作用。钠离子转运体和钾离子转运体在嗜盐耐盐微生物中广泛存在,其"保钾排钠"机制是微生物抗盐胁迫的两大策略之一。近年来,嗜盐耐盐微生物中许多新型钠、钾离子转运体被陆续发现,如RDD蛋白、UPF0118蛋白、DUF蛋白和KimA蛋白等;Fe³⁺、Mg²⁺等其他金属离子的转运蛋白也被证实可通过影响微生物胞内相容性溶质的合成起到渗透调节的作用。本文综述了嗜盐耐盐微生物中抗盐胁迫相关的各类离子转运蛋白,分析其分子结构和工作机理,并对这些蛋白在农业方面的应用进行了展望。继续发现新的离子转运蛋白,探究抗盐胁迫相关离子转运蛋白的结构和机理,解析各转运系统的协同作用及分子调控机制,将进一步加深对嗜盐耐盐微生物抗盐胁迫调控的认识,并为盐碱地农作物的改良等提供新的思路。     

Development and use of probability models: The industry perspective

Summary In the processed meat industry, food safety and microbiological shelf life issues lend themselves to the use of probability modeling. Our research concentrated on predicting the effectiveness of sodium lactate as an antibotulinal agent in vacuum packaged, uncured and cured turkey breast model systems. In uncured turkey breast containing 1.4% NaCl, 0.3% Na phosphate, and 0–3% Na lactate, the antibotulinal effect of sodium lactate can be predicted using the following model: Days to toxicity = 3.13+0.39(Na lactate)². Using cured turkey breast with 0.3% Na phosphate, 0.2% sucrose, 0–3% Na lactate, the time to toxicity can be predicted from the following model: Days to toxicity = 1.69+4.88(NaCl)–11.16(Na lactate)+7.23(Na lactate)². Probability models have also been developed to predict the refrigerated shelf life of specific processed meat products. The usefulness of the predictive modeling for food safety and quality in the food industry will also be discussed.This paper was presented at The International Conference on the Application of Predictive Microbiology and Computer Modeling Techniques to the Food Industry, April 12–15 1992, Hyatt Regency Hotel, Tampa, FL, USA.     

Structure of the cytochrome c oxidase complex: labeling by hydrophilic and hydrophobic protein modifying reagents

Beef heart cytochrome c oxidase has been reacted with [35S]diazobenzenesulfonate ([35S]DABS), [35S]-N-(4-azido-2-nitrophenyl)-2-aminoethylsulfonate ([35S]NAP-taurine), and two different radioactive arylazidophospholipids. The labeling of the seven different subunits of the enzyme with these protein modifying reagents has been examined. DABS, a water-soluble, lipid-insoluble reagent, reacted with subunits II, III, IV, V, and VII but labeled I or VI only poorly. The arylazidophospholipids, probes for the bilayer-intercalated portion of cytochrome c oxidase, labeled I, III, and VII heavily and II and IV lightly but did not react with V or VI. NAP-taurine labeled all of the subunits of cytochrome c oxidase. Evidence is presented that this latter reagent reacts with the enzyme from outside the bilayer, and the pattern of labeling with the different hydrophilic and hydrophobic labeling reagents is used to derive a model for the arrangement of subunits in cytochrome c oxidase.     

The most conserved nuclear-encoded polypeptide of cytochrome c oxidase is the putative zinc-binding subunit: primary structure of subunit V from the slime mold Dictyostelium discoideum.

A full-length 515 base pairs cDNA for cytochrome c oxidase subunit V of D. discoideum was isolated from a lambda gt11 expression library. The encoded polypeptide, whose identity was confirmed by partial protein sequencing, is 119 amino acids long (Mr = 13,352) and does not contain a cleavable presequence. The protein, which is homologous to human subunit Vb and yeast subunit IV, exhibits the highest degree of sequence conservation found among nuclear-encoded subunits of cytochrome c oxidase from distantly related organisms. All the invariant residues are clustered in two regions of the C-terminus which include the putative amino acids involved in the coordination of the Zn ion tightly associated to eukaryotic oxidase.