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1.
Genes for the biosynthesis of spinosyns: applications for yield improvement in Saccharopolyspora spinosa 总被引:2,自引:0,他引:2
K Madduri C Waldron P Matsushima M C Broughton K Crawford D J Merlo R H Baltz 《Journal of industrial microbiology & biotechnology》2001,27(6):399-402
Spinosyns A and D are the active ingredients in an insect control agent produced by fermentation of Saccharopolyspora spinosa. Spinosyns are macrolides with a 21-carbon, tetracyclic lactone backbone to which the deoxysugars forosamine and tri-O-methylrhamnose are attached. The spinosyn biosynthesis genes, except for the rhamnose genes, are located in a cluster that
spans 74 kb of the S. spinosa genome. DNA sequence analysis, targeted gene disruptions and bioconversion studies identified five large genes encoding type
I polyketide synthase subunits, and 14 genes involved in sugar biosynthesis, sugar attachment to the polyketide or cross-bridging
of the polyketide. Four rhamnose biosynthetic genes, two of which are also necessary for forosamine biosynthesis, are located
outside the spinosyn gene cluster. Duplication of the spinosyn genes linked to the polyketide synthase genes stimulated the
final step in the biosynthesis — the conversion of the forosamine-less pseudoaglycones to endproducts. Duplication of genes
involved in the early steps of deoxysugar biosynthesis increased spinosyn yield significantly. Journal of Industrial Microbiology & Biotechnology (2001) 27, 399–402.
Received 31 May 2001/ Accepted in revised form 09 July 2001 相似文献
2.
Abstract Broad host-range RK2-based cosmid vectors ('costramids') are increasingly used in molecular genetic studies of Gram-negative soil bacteria such as Rhizobium spp. we describe a simple modification of existing methods, whereby a genomic library constructed in a stringently replicated vector can be screened for genes which are undetectable by colony hybridization due to background cross-hybridization. This method allows the use of 'heterologous' probes (interspecies hybridization) to isolate several presumptive genes of interest from a gene bank of Rhizobium sp. NGR234 made in the costramid pRK7813. These are a gene with homology to the citrate synthase gene ( gltA ) or Escherichia coli , the gene encoding δ-aminol evulinic acid synthase ( hemA ), and a gene or genes regulating dicarboxylate transport. 相似文献
3.
4.
A gene encoding the endogenous superantigen Mlsc, which deletes Tcrb-V3+ T cells in the NOD inbred mouse strain, was found to co-segregate with Mtv-3 on chromosome 11. This identifies a fourth gene encoding a deletion ligand for Tcrb-V3+ T cells and extends recently published observations in support of the hypothesis that a number of endogenous superantigens are the products of Mtv proviruses.
Address correspondence and offprint requests to : K. Tomonari. 相似文献
5.
A total of 34 isolates ofListeria monocytogenes were tested against ampicillin, cephalothin, chloramphenicol, erythromycin, tetracycline, and penicillin-G using the Autobac 3-h AIS and the Autobac 5-h MIC procedures. The results were compared to susceptibility category interpretations and MICs determined using the Sceptor system. With the Sceptor System, all isolates were interpreted to be moderately susceptible to ampicillin and penicillin-G, and susceptible to the four other antibiotics. With the Autobac AIS, all isolates were interpreted to be susceptible to all the antibiotics except penicillin-G. All but one of the 34 isolates were interpreted to be resistant to penicillin-G with the Autobac AIS test. The remaining isolate was interpreted to be indeterminant. The Autobac AIS test was unsatisfactory for determining the susceptibility ofL. monocytogenes isolates to penicillin-G. The Autobac MIC results correlated well with the MIC results of the Sceptor system provided that the Autobac was programmed as though it were testing enterococci. The Autobac MIC reported penicillin-G MICs in units per milliliter and required the use of a conversion factor to obtain micrograms per milliliter, and did not allow for the testing of erythromycin. The Autobac MIC susceptibility category interpretations must not be used, as they were derived from an outdated susceptibility standard. The Autobac MIC test may be used if the limitations given above are observed. 相似文献
6.
Dietary unsaturated fatty acids: interactions and possible needs in relation to eicosanoid synthesis 总被引:11,自引:0,他引:11
In addition to providing energy and essential fatty acids, dietary fatty acids can affect numerous biochemical and physiologic reactions related to secretory, cardiovascular, and immune functions. The major dietary unsaturated fatty acid, linoleic acid, affects tissue arachidonic acid and can influence eicosanoid-mediated reactions. Chronic, excess, or imbalanced eicosanoid synthesis may be conductive to excessive inflammation, thrombotic tendencies, atherosclerosis, and immune suppression. Dietary n-3 polyunsaturated fatty acids (PUFAs) may ameliorate eicosanoid-related phenomena by reducing tissue arachidonic acid and by inhibiting eicosanoid synthesis. This review summarizes information concerning the metabolism of unsaturated fatty acids, with emphasis on tissue arachidonic acid levels and eicosanoids, and discusses the need for data concerning the appropriate intake of dietary n-6 and n-3 PUFAs to modulate arachidonic acid and eicosanoid synthesis and to minimize possible adverse reactions. 相似文献
7.
John Stanley David N. Dowling William J. Broughton 《Molecular & general genetics : MGG》1988,215(1):32-37
Summary The hemA gene which encodes -aminolaevulinic acid synthase (ALAS), was cloned and characterized from the broad host-range Rhizobium strain NGR234. A cosmid, identified by hybridization with the cloned gene of R. meliloti and complementation of an R. meliloti hemA mutant, was subcloned to yield a 5.5 kb fragment containing the entire NGR234 gene. A physical-genetic map was made and the interposon was introduced into a single EcoRI site which bisects the gene. The mutated gene was homogenotized into NGR234 to generate a hemA mutant, with a view to evaluating the role of rhizobial bacteroid ALAS activity for a wide variety of legume symbioses. The mutant strain formed an ineffective (Fix–) symbiosis with all tested host plants. These included tropical legumes that produce either indeterminate (Leucaena) or determinate (Desmodium, Macroptilium, Lablab, Vigna) root nodules.Abbreviations ALA
-aminolaevulinic acid
- ALAS
aminolaevulinic acid synthase
- Lb
leghaemoglobin
- Lb-haem
haem moiety of leghaemoglobin 相似文献
8.
H Y Ahn L F Sue J K Ma C A Pinkstaff R S Pore D O Overman C J Malanga 《Biochimica et biophysica acta》1988,966(1):122-132
The ability of the isolated gill epithelium of Mytilus edulis to incorporate [14C]glucosamine as a precursor in the biosynthesis and secretion of mucous glycoproteins was investigated. Localization of mucous cells in the gill filament was achieved using histochemical staining techniques. Mucus cells containing neutral and acidic mucins were found in the lateral region, whereas mucus cells containing primarily neutral or sulfated mucins were found in the abfrontal region. Autoradiographic results showed that in both regions, the mucous cells were rich in content of the incorporated radiolabel. The secreted glycoproteins containing the incorporated radiolabel were analyzed by column chromatography using Bio-Gel P-2 and P-6. Two populations of the glycoproteins differing in molecular size were isolated. Upon alkaline reductive borohydride cleavage of the O-glycosidic linkages of the high molecular weight protein, about 70% of the radiolabel and 85% of the carbohydrate content were removed from the protein. The alkaline borohydride cleavage resulted in the formation of at least six oligosaccharide chains of various lengths of sugar units. Gas chromatographic analysis of the carbohydrate composition shows that the glycoproteins contain N-acetylglucosamine, N-acetylgalactosamine, and galactose, fucose, and mannose as the neutral monosaccharides. The above results indicate that the isolated gill epithelium of M. edulis is capable of incorporating [14C]glucosamine in the synthesis of secretable mucin-type glycoproteins. 相似文献
9.
Summary The most widely used technique of leaf water potential measurements is with the Scholander pressure chamber. Representative leaf water potential values require many determinations on individual leaves and this can be time consuming in large fields or experiments with multiple treatments. This paper describes a method of obtaining a mean value more rapidly, by using two leaves in the pressure chamber at the same time, but recording the end point of each leaf separately. 相似文献
10.
Yvonne H. Edwards Sue Povey Kay M. Levan Catherine E. Driscoll Jose Luis Millan Erwin Goldberg 《Genesis (New York, N.Y. : 2000)》1987,8(4):219-232
From the data presented in this report, the human LDHC gene locus is assigned to chromosome 11. Three genes determine lactate dehydrogenase (LDH) in man. LDHA and LDHB are expressed in most somatic tissues, while expression of LDHC is confined to the germinal epithelium of the testes. A human LDHC cDNA clone was used as a probe to analyze genomic DNA from rodent/human somatic cell hybrids. The pattern of bands with LDHC hybridization is easily distinguished from the pattern detected by LDHA hybridization, and the LDHC probe is specific for testis mRNA. The structural gene LDHA has been previously assigned to human chromosome 11, while LDHB maps to chromosome 12. Studies of pigeon LDH have shown tight linkage between LDHB and LDHC leading to the expectation that these genes would be syntenic in man. However, the data presented in this paper show conclusively that LDHC is syntenic with LDHA on human chromosome 11. The terminology for LDH genes LDHA, LDHB, and LDHC is equivalent to Ldhl, Ldh2, and Ldh3, respectively. 相似文献