Tokujiro Aida

Characteristics of DNA and Multiple rpoD Homologs of Microcystis(Synechocystis) Strains

The base compositions of DNAs from nine Microcystis strains, as determined by high-performance liquid chromatography, were 41 to 42 mol% G+C. Chromosomal DNAs derived from these strains were found to be extremely resistant to many restriction endonucleases, and a restriction analysis revealed the presence of a dam-like methylase or both dam- and dcm-like methylases in all of the strains examined. Genomic Southern hybridization in which a synthetic oligonucleotide probe (rpoD probe) was used showed that members of the genus Microcystis might have multiple rpoD homologs, and the hybridization signal patterns observed with the DNAs of Microcystis aeruginosa strains were different from each other.

Production of γ-Polyglutamic Acid by Bacillus licheniformis A35 under Denitrifying Conditions

The possibility of producing amino acids under conditions of denitrification, i.e., with nitrate respiration as an energy-supplying system, was investigated using denitrifying bacteria. We found that Bacillus licheniformis A35 accumulated γ-polyglutamic acid (PGA) to a concentration of 8 mg per ml in a medium containing glucose and ammonium chloride or glutamic acid under denitrifying conditions. The bacterium also produced PGA aerobically. Thus, we found the de novo synthesis of PGA with B. licheniformis A35. The optimum conditions for PGA production were determined.The purified PGA was found to be composed solely of glutamic acid; both d- and l-glutamic acid, in a molar ratio of 4:1. The molecular weight of PGA was about 3 × 105.Other bacilli tested produced some free amino acids but not under nitrate-respiration conditions, although some of them did produce PGA aerobically from l-glutamic acid.

Cloning, sequencing and characterization of the gene encoding a principal sigma factor homolog from the cyanobacterium Microcystis aeruginosa K-81.

We cloned and sequenced the rpoD1 gene of Microcystis aeruginosa K-81, a unicellular colony-forming cyanobacterium that can perform photosynthesis involving light-responsive gene expression. The deduced amino acid sequence of RpoD1 exhibited extensive homology to the other eubacterial principal sigma factors. Primer extension and Western blot analyses revealed that the rpoD1 gene, which encodes a principle sigma factor homolog, had two transcription start points, P1 and P2. These transcripts, and the corresponding protein, constitutively appeared in M. aeruginosa, irrespective of light or dark conditions.

Novel spectroscopic aspects of type I copper in Hyphomicrobium nitrite reductase

Copper-containing nitrite reductase isolated from Hyphomicrobium sp. A 3151 has been characterized by electronic absorption, circular dichroism (CD) and electron paramagnetic resonance (EPR) spectroscopies. The visible absorption spectrum of Type I copper (blue copper) in the enzyme especially indicates novel features compared with those of Type I coppers in not only several nitrite reductases already reported but also small blue copper proteins. The EPR spectrum of Type I copper exhibits an axial symmetry.

Intracellular Colistin-like Active Substance of Bacillus colistinus and Interaction of Cellular Protein with Colistin

A colistin-like active substance was found in the cell extract of colistin-producing organism, Bacillus colistinus. This substance was designated colistin X and differed from known colistin on bioautograms and on gel filtration on Sephadex G-100 where it appeared in a protein fraction. Binding of 14C-labeled colistin with the cellular protein of the organism was noted in low colistin ratios, such as approximately 260 u/mg protein, by incorporating radioactivity into the protein fraction in gel filtration. The paper radiogram of the binding reaction mixture gave a radioactive spot corresponding to colistin X. In contrast, in high colistin ratios the cellular protein used was partially degraded by reaction with colistin.From these results, it was assumed that the intracellular colistin X was a binding complex of colistin and cellular protein.