6-Hydroxypelargonidin glycosides in the orange-red flowers of Alstroemeria

Two 6-hydroxypelargonidin glycosides were isolated from the orange-red flowers of Alstroemeria cultivars, and determined to be 6-hydroxypelargonidin 3-O-(beta-D-glucopyranoside) and 3-O-[6-O-(alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside], respectively, by chemical and spectroscopic methods. In addition, five known anthocyanidin glycosides, 6-hydroxycyanidin 3-malonylglucoside, 6-hydroxycyanidin 3-rutinoside, cyanidin 3-malonylglucoside, cyanidin 3-rutinoside and pelargonidin 3-rutinoside were identified in the flowers.     

Efficient release of overproduced gene products from Escherichia coli BL21(DE3) by lytic infection with newly isolated bacteriophages

Overproduced proteins from Escherichia coli BL21(DE3) were efficiently released with virulent bacteriophages. Leviviridae-like bacteriophages were isolated from soil and used to lyse BL21(DE3) cells transformed with beta-glucosidase, chitinase, or chitosanase genes. This method caused lysis of bacterial cells similar to that by conventional sonication and enabled us to effectively recover and purify the enzymes.     

Microbial metalloproteases and pathogenesis

Zinc metalloproteases produced by human pathogenic microorganisms show a wide variety of pathological actions. In local infections, the proteases cause necrotic or hemorrhagic tissue damage through digestion of structural components of the ground substance, and also form edematous lesions through generation of inflammatory mediators, while in systemic infections, the proteases act as a synergistic virulence factor through disordered proteolysis of many plasma proteins. Clostridial neurotoxins, Bacteroides fragilis enterotoxin and Bacillus anthracis lethal factor are also zinc metalloproteases.     

Systematic synthesis of sulfated sialyl-alpha-(2 --> 3)-neolactotetraose derivatives and their acceptor specificity for an alpha-(1 --> 3)-fucosyltransferase (Fuc-TVII) involved in the biosynthesis of L-selectin ligand

Sulfated sialyl-alpha-(2 --> 3)-neolactotetraose (IV3NeuAcnLcOse4) derivatives at C-6 of GlcNAc (6-O-sulfo), terminal Gal (6'-O-sulfo), and both GlcNAc and Gal (6,6'-di-O-sulfo) residues have systematically been synthesized. (Methyl 5-acetamido-4,7,8,9- tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosy lonate)-(2 --> 3)-2,4-di-O-benzoyl-6-O-levulinoyl-D-galactopyranosyl trichloroacetimidate was coupled with 2-(trimethylsilyl)ethyl (2-acetamido-2-deoxy- 3-O-benzyl-6-O-p-methoxyphenyl-beta-D-glucopyranosyl)-(1 --> 3)-(2,4,6-tri-O-benzyl-beta-D-galactopyranosyl)-(1 --> 4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside to give the suitably protected pentasaccharide which, upon selective removal of the p-methoxyphenyl and/or levulinoyl groups at C-6 of the GlcNAc and the terminal Gal residues, successive O-sulfation(s) and deprotection, afforded the desired three sulfated IV3NeuAcnLcOse4 derivatives. Acceptor specificity of the synthetic IV3NeuAcnLcOse4 probes for a human alpha-(1 --> 3)-fucosyltransferase (Fuc-TVII) was examined to study the biosynthetic pathway of L-selectin ligand. Only the 6-sulfated derivative at C-6 of GlcNAc was recognized by Fuc-TVII to give 6-O-sulfo sialyl LeX.     

The promoter of rbcS in a C3 plant (rice) directs organ-specific,light-dependent expression in a C4 plant (maize), but does not confer bundle sheath cell-specific expression

The small subunit of ribulose-bisphosphate carboxylase (Rubisco), encoded by rbcS, is essential for photosynthesis in both C3 and C4 plants, even though the cell specificity of rbcS expression is different between C3 and C4 plants. The C3 rbcS is specifically expressed in mesophyll cells, while the C4 rbcS is expressed in bundle sheath cells, and not mesophyll cells. Two chimeric genes were constructed consisting of the structural gene encoding -glucuronidase (GUS) controlled by the two promoters from maize (C4) and rice (C3) rbcS genes. These constructs were introduced into a C4 plant, maize. Both chimeric genes were specifically expressed in photosynthetic organs, such as leaf blade, but not in non-photosynthetic organs. The expressions of the genes were also regulated by light. However, the rice promoter drove the GUS activity mainly in mesophyll cells and relatively low in bundle sheath cells, while the maize rbcS promoter induced the activity specifically in bundle sheath cells. These results suggest that the rice promoter contains some cis-acting elements responding in an organ-pecific and light-inducible regulation manner in maize but does not contain element(s) for bundle sheath cell-specific expression, while the maize promoter does contain such element(s). Based on this result, we discuss the similarities and differences between the rice (C3) and maize (C4) rbcS promoter in terms of the evolution of the C4 photosynthetic gene.     

Knocking out a specific tRNA species within unfractionated Escherichia coli tRNA by using antisense (complementary) oligodeoxyribonucleotides

Methods for the preparation of an Escherichia coli tRNA mixture lacking one or a few specific tRNA species can be the basis for future applications of cell-free protein synthesis. We demonstrate here that virtually a single tRNA species in a crude E. coli tRNA mixture can be knocked out by an antisense (complementary) oligodeoxyribonucleotide. One out of five oligomers complementary to tRNA^Asp blocked the aspartylation almost completely, while minimally affecting the aminoacylation with other 13 amino acids tested. This `knockout' tRNA behaved similarly to the untreated tRNA in a cell-free translation of an mRNA lacking Asp codons.     

Phylogeny of Allium L. subg. Melanocrommyum (Webb et Berth.) Rouy based on DNA sequence analysis of the internal transcribed spacer region of nrDNA

 Sequence analysis of the ITS region of nuclear ribosomal DNA from subgeneric representatives of Allium L. produced phylogenetic trees which concurred with previous conclusions based on classical taxonomy. Phylogenetic analysis revealed a closer relationship between Nectaroscordum siculum and Allium cernuum (representing Amerallium) than between A. cernuum and the rest of the Allium species employed in this study. The phylogeny of subg. Melanocrommyum based on ITS sequences largely agreed with inferences made by previous researchers based on morphology or a restriction analysis of chloroplast DNA. However, the phylogenetic positions of Allium protensum and Allium macleanii based on ITS sequences did not correspond to their morphological similarity with Allium schubertii and Allium giganteum, respectively. Received: 15 February 1998 / Accepted: 12 March 1998     

Target proteins of the cytosolic thioredoxin in Plasmodium falciparum

The target proteins of a cytosolic Trx (PfTrx-1) in Plasmodium falciparum with Trx-affinity chromatography were examined. Based on the Trx protein reduction pathway, we generated a cysteine mutant of PfTrx-1, which captures the target protein as a mixed disulfide intermediate. A number of proteins were captured with PfTrx-1(C33S) immobilized on resin and were eluted by DTT treatment. The PfTrx-1(C33S) immobilized resin-captured proteins were trypsin-digested and analyzed on a liquid chromatography-mass spectrometry system. Analysis of the sequence data against databases assigned 20 proteins, four of which had been found previously in P. falciparum, with the remaining 16 being new targets. The potential Trx-target proteins included those in pathways such as the redox cycle, protein biosynthesis, energy metabolism and signal transduction. We captured 4 enzymes in the glycolysis pathway (hexokinase, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate mutase and l-lactate dehydrogenase (LDH)) as Trx-targets, and we found that PfTrx-1 enhanced the activity of PfGAPDH and PfLDH.