Synthesis, NMR kinetics and dynamic structure of a 17-mer heptaloop RNA hairpin carrying a 3--methyluridine nucleotide residue in the loop region.

A 17-mer RNA hairpin (5'GGGAGUAGCGGCUCCC3') carrying 3--methyluridine (m3U) at position (m3U7-RNA), designed to represent the anticodon stem-loop (ACSL) region of tRNAs to study an open loop state (O-state), was synthesized, purified by HPLC, and characterized by MALDI-ToF_MS and NMR methods. H-NMR data revealed primary (P-state in 56.1%), secondary (S-state in 43.

Use of the parmbsc0 force field and trajectory analysis to study the binding of netropsin to the DNA fragment (5'CCAATTGG)(2) in the presence of excess NaCl salt in aqueous solution.

The parmbsc0 force field was applied to study in detail the binding of netropsin, at a salt concentration of 0.28M Na(+), to the minor groove of an 8-mer (5'CCAATTGG)(2) DNA duplex forming a netropsin·DNA complex which previously has been characterized by X-ray crystallography, albeit with the use of closely related DNA duplexes. The X-ray structure revealed that the terminal guanidinium and amidinium groups of netropsin interact with the extreme ends of the palindromic AATT sequence of the receptor DNA.

NMR and amber analysis of the neamine pharmacophore for the design of novel aminoglycoside antibiotics.

The dependence of the solution structure of neamine on pH was determined by NMR and AMBER molecular dynamics methods at pD 3.3, pD 6.5, and pD 7.

Role of DNA protection and repair in resistance of Bacillus subtilis spores to ultrahigh shock pressures simulating hypervelocity impacts.

Impact-induced ejections of rocks from planetary surfaces are frequent events in the early history of the terrestrial planets and have been considered as a possible first step in the potential interplanetary transfer of microorganisms. Spores of Bacillus subtilis were used as a model system to study the effects of a simulated impact-caused ejection on rock-colonizing microorganisms using a high-explosive plane wave setup. Embedded in different types of rock material, spores were subjected to extremely high shock pressures (5 to 50 GPa) lasting for fractions of microseconds to seconds.

Microbial rock inhabitants survive hypervelocity impacts on Mars-like host planets: first phase of lithopanspermia experimentally tested.

The scenario of lithopanspermia describes the viable transport of microorganisms via meteorites. To test the first step of lithopanspermia, i.e.

Transferable Streptomyces DNA amplification and coamplification of foreign DNA sequences.

The 8.8-kb amplifiable unit of DNA of Streptomyces achromogenes subsp. rubradiris, AUD-Sar 1, which carries 0.

DNA amplification in Streptomyces achromogenes subsp. rubradiris is accompanied by a deletion, and the amplified sequences are conditionally stable and can be eliminated by two pathways.

Southern blot analysis of BglII-digested DNA isolated from wild-type Streptomyces achromogenes, which harbors the 8.8-kilobase amplifiable unit of DNA, AUD-Sar 1, and of similarly digested DNA from 12 strains carrying an array of 200 to 300 tandem copies of a specific AUD-Sar 1-derived 8.0-kilobase DNA sequence, ADS-Sar 1, revealed the absence of the 12.

Spectinomycin resistance and associated DNA amplification in Streptomyces achromogenes subsp. rubradiris.

Streptomyces achromogenes subsp. rubradiris plated at low density on 1,000 micrograms of spectinomycin per ml initially produces slow-growing, bald colonies from which arise, in a spatially and temporally random fashion, foci of rapidly growing aerial mycelium-forming cells whose DNA contains an approximately 200- to 300-fold amplification of an 8-kilobase (kb) sequence. This sequence was cloned in Escherichia coli on pBR322 and physically characterized.

Lack of influence of the carbamoyl group on the stereochemistry of the acid-catalyzed opening of the aziridine ring of the mitomycins and of congeners.

The acid-catalyzed opening of the aziridine ring of mitomycins A and C is known to occur predominantly with cis stereochemistry. We have observed that the presence or absence of a carbamoyl group at C-10 of mitomycin C and in certain of its analogues does not have a significant influence on the stereochemistry of the opening of this ring. The trans product obtained from mitomycin C was shown to be stable when treated with acid under the conditions of its formation.

Studies on the biosynthesis of the antibiotic streptozotocin (streptozocin) by Streptomyces achromogenes var. streptozoticus. Feeding experiments with carbon-14 and tritium labelled precursors.

Feeding experiments and chemical degradations have shown that D-[1(-14)C,2(-3)H]-and-[1(-14)C,6(-3)H] glucosamine, L-[ureido-14C] citrulline, L-[guanidino-14C] arginine and L-[14CH3] methionine specifically label the glucosamine moiety, the urea carbonyl and the N-methyl group of the antibiotic streptozotocin, respectively. Feeding these precursors in amounts of 5 approximately 10 mumoles per 100 ml of culture medium under conditions where the fermentation yielded approximately 20 mumoles of streptozotocin in 24 hours gave incorporation rates which approached 40%. Upon feeding 100 mumoles of either D-[1(-14)C] glucosamine or L-[ureido-14C] citrulline they were incorporated into newly synthesized streptozotocin essentially without dilution by endogeneous precursors.

Nitroalkane oxidation by streptomycetes.

Crude cell-free extracts of nine strains of Streptomyces tested for nitroalkane-oxidizing activity showed production of nitrous acid from 2-nitropropane, 1-nitropropane, nitroethane, nitromethane, and 3-nitropropionic acid. These substrates were utilized in most strains but to a decreasing extent in the order given, and different strains varied in their relative efficiency of oxidation. p-Nitrobenzoic acid, p-aminobenzoic acid, enteromycin, and omega-nitro-l-arginine were not attacked.

Isolation and characterization of tryptophan transaminase and indolepyruvate C-methyltransferase. Enzymes involved in indolmycin biosynthesis in Streptomyces griseus.

Two enzymes, tryptophan transaminase and indolepyruvate C-methyltransferase, which are active in the initial steps of the biosynthetic pathway of the antibiotic indolmycin, have been detected and partially purified from cell-free extracts of Streptomyces griseus. The transaminase has been purified 3-fold by ammonium sulfate fractionation. At this stage of purification, it catalyzes the alpha-ketoglutarate and pyridoxal phosphate-dependent transamination of L-tryptophan, 3-methyltryptophan, L-pphenylalanine, and L-tyrosine.