In Saccharomyces cerevisiae, the meiotic process is accompanied by a large increase in 1,3-13-glucandegradative activity. The molecular cloning of the gene (SSGI) encoding a sporulation-specific exo-1,3-,3-glucanase was achieved by screening a genomic library with a DNA probe obtained by polymerase chain reaction amplification using synthetic oligonucleotides designed according to the nucleotide sequence predicted from the amino-terminal region of the purified protein. The meiotic process in the yeast Saccharomyces cerevisiae, triggered upon starvation of MATa/MATct diploid strains, represents a regulated program of cellular differentiation in a relatively simple eukaryote, which includes genetic recombinations, meiotic divisions, and the encapsulation of the four haploid nuclei into progeny ascospores. As a model system for studying development, research has been directed largely toward identifying the cytological, biochemical, and genetic events that occur during sporulation and evaluating the extent to which such events are important to the process. Some of them may merely be a physiological response to changes in the conditions needed to induce sporulation and perhaps play no role at all in meiosis or spore formation. Such changes would probably occur in nonsporulating cells under the same changing conditions.
Many types of tumor, including glioma, melanoma, non-small cell lung, esophageal, head and neck cancer, among others, are intrinsically resistant to apoptosis induction and poorly responsive to current therapies with proapoptotic agents. In addition, tumors often develop multi-drug resistance based on the cellular efflux of chemotherapeutic agents. Thus, novel anticancer agents capable of overcoming these intrinsic or developed tumor resistance mechanisms are urgently needed. We describe a series of 2-aryl-2-(3-indolyl)acetohydroxamic acids, which are active against apoptosis- and multidrug-resistant cancer cells as well as glioblastoma neurosphere stem-like cell cultures derived from patients. Thus, the described compounds serve as a novel chemical scaffold for the development of potentially highly effective clinical cancer drugs.
The synthesis and secretion of a 1,3-1,4-,B-D-glucanase were studied in different strains of Escherichia coli transformed with plasmids carrying the BaciUus circulans WL-12 1,3-1,4-j3-D-glucanase structural gene. This gene (named BGC) is contained within a 1.9-kilobase BamHI-HindM fragment and directs the synthesis in E. coli of an enzyme that specifically degrades lichenan. Only one active form of the enzyme was found when the gene was expressed in different E. coli strains. The electrophoretic pattern of this protein showed a molecular weight that was approximately the same as that of the mature 0-glucanase secreted from B. circulans suggesting that the processing of this protein may be similar in both species. As deduced from maxicell experiments, the Bacilus parental promoter directs the synthesis in E. coli. Pulse-chase experiments showed that the protein may be cotranslationafly processed.Species of the genus Bacillus synthesize a broad variety of extracellular hydrolytic enzymes with different activities, some of which have been extensively studied in view of their commercial importance (28). The advent of genetic engineering technology has focused interest on the production of such enzymes. On one hand, the characterization of the genetic systems controlling their synthesis may represent a crucial step for increasing their yield for industrial purposes. On the other hand, knowledge of the mechanisms of secretion of these enzymes may contribute to a much better understanding of the phenomenon of protein export in gram-positive bacteria in general and the use of bacilli as hosts for the secretion and efficient synthesis of foreign proteins in particular.Exocellular 1-glucanases are produced by many members of the Bacillaceae family. Among them, some act asglucan-endohydrolases, hydrolyzing mixed-linked 1-glucans containing 1,3-1-and 1,4-,B-linkages, such as lichenan and barley 1-glucan. The fact that these bacterial enzymes possess a substrate range similar to that of the lichenase of germinating barley has increased their potential value for the brewing industry as substitutes and supplements of malt enzymes to hydrolyze barley ,B-glucans during the brewing process. Genes coding for this kind of carbohydrolase have been cloned from different species'of'Bacillus such as B. subtilis and B. amyloliquefaciens; some of these genes have also been sequenced.Bacillus circulans WL-12 is a gram-positive microorganism isolated by Tanaka and Phaff (36) from soil samples and characterized by its ability to lyse a number of fungal and yeast cell walls. This organism synthesizes a number of carbohydrolases such as a-glucanases, chitinases, 1-xylanases, and 1-glucanases (13). Among the latter, 1,3-1-glucanases and 1,6-13-glucanases have been characterized (7,35 We have detected in culture supernatants of this microorganism an endo-1,3-1,4-,B-glucanase, which is not produced until the stationary phase of growth. In the present work we describe the cloning and expression of this B. circulans 1-glucanase gene in Escheri...
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