An endogalactosaminidase from Streptomyces griseus.

An endogalactosaminidase has been purified 34-fold from the culture filtrate of Streptomyces griseus. This enzyme cleaves GalN-GalN linkages in oligogalactosaminoglycan, a galactosamine-rich oligosaccharide isolated from the culture filtrate of a Neurospora mutant. Since some or all of the GalN-GalN bonds in this molecule link positions 1 and 4, and are in the alpha-configuration, we are probably dealing with an endo-alpha-(1 leads to 4)-galactosaminidase, bu this characterization is only tentative because the few bonds cleaved by the enzyme could have a different structure. The enzyme is inactive towards N-acetyl-oligogalactosaminoglycan and chitosan. The endogalactosaminidase preparations also cleave high molecular weight galactosaminoglycan (obtained from Neurospora) into fragments greater than or equal to 10(4) daltons in molecular weight, and catalyze the release of Neurospora sporelings from the glass surfaces to which they are anchored. Galactosaminoglycan-cleaving and sporeling-releasing activities elute jointly from DEAE-cellulose columns. This observation provides further support for an earlier proposal that the sporelings are anchored to the glass by means of galactosaminoglycan molecules.     

Chromogenesis mirabilis in Streptomyces griseus

A number of chromogenic Streptomyces, producing diffusible melanoid pigment on complex organic media, fail to form melanin pigment on conventionally used synthetic tyrosine agar. By means of our new melanin formation test, almost all the chromogenic streptomyces can now be detected in chemically defined medium. In contrast to ordinary chromogenic streptomyces, two streptomyces species of the International Streptomyces Project, S. griseus ISP 5236 and S. ornatus ISP 5307, produce melanin pigment only on synthetic tyrosine agar, without showing chromogenicity on complex organic media. From the results obtained with S. griseus ISP 5236 and S. phaeochromogenes ISP 5073, it was revealed that melanin formation by Streptomyces, in general, is inhibited by L-cysteine present in organic nitrogen sources incorporated into natural media. Most chromogenic species of streptomyces produce a higher level of tyrosinase and rapidly utilize L-cysteine in the culture media which result in the manifestation of good chromogenicity on natural media. Peculiarity of chromogenicity of S. griseus and S. ornatus might be due to the lower ability to produce tyrosinase and to utilize L-cysteine in the culture medium.     

Genetic recombination in Streptomyces griseus.

Low-frequency (10(-6)) genetic recombination was observed in a cephamycin-producing strain of Streptomyces griseus. The recombinants were predominantly heteroclones. Heteroclone analysis was performed involving four heteroclones of one cross. In 100 mutants correlation was found between the type of auxotrophy and the level of antibiotic activity. A cross of this strain with a streptomycin-producing strain of S. griesus is described.     

Chromosomal arm replacement in Streptomyces griseus

UV irradiation of Streptomyces griseus 2247 yielded a new chromosomal deletion mutant, MM9. Restriction and sequencing analysis revealed that homologous recombination between two similar lipoprotein-like open reading frames, which are located 450 and 250 kb from the left and right ends, respectively, caused chromosomal arm replacement. As a result, new 450-kb terminal inverted repeats (TIRs) were formed in place of the original 24-kb TIRs. Frequent homologous recombinations in Streptomyces strains suggest that telomere deletions can usually be repaired by recombinational DNA repair functioning between the intact and deleted TIR sequences on the same chromosome.     

Properties of Streptomyces griseus aminopeptidase

The paper deals with studying the properties of aminopeptidase isolated from Str. griseus culture fluid. The preparation is characterized by a high specific activity and heat stability, it has no admixtures of carboxypeptidases and proteinases. The enzyme is easily inhibited by EDTA, but the addition of Ca2+ evokes its complete reactivation. A partial recovery of the activity may be also reached under the influence of some other bivalent metals. In hydrolysis of di- and tripeptides it is shown that the enzyme has a preferential effect on the substrates with N-terminal leucine. Peptides with N-terminal alanine, valine and glycine are almost not hydrolyzed. The use of the native insulin and decapeptide with the known amino acidic sequence as substrates shows that aminopeptidase can hydrolyze proteins and peptides with the successive release of some amino acids: phenylalanine, serine triptophane, valine, asparagine, etc. Glycine is difficult for removal and may inhibit the further hydrolysis of the polypeptide chain.     

L-Asparaginase Production by Streptomyces griseus

Streptomyces griseus ATCC 10137 synthesizes about 1 IU of L-asparaginase/100 ml of a 4% peptone medium. The enzyme has a pH optimum of 8.5 which is comparable to that of the L-asparaginase derived from Escherichia coli which has antitumor properties.     

Molecular cloning and nucleotide sequence of Streptomyces griseus trypsin gene.

Streptomyces griseus trypsin (E.C. 3.4.21.4) is one of the major extracellular proteinase, which is secreted by S. griseus. The gene encoding S. griseus trypsin was isolated from a S. griseus genomic library by using a synthetic oligonucleotide probe. Fragments containing the gene for S. griseus trypsin were characterized by hybridization and demonstration of proteolytic activity in S. lividans. Deduced amino acid sequence from the nucleotide sequence suggests that S. griseus trypsin is produced as a precursor, consisting of three portions; an amino-terminal pre sequence (32 amino acid residues), a pro sequence (4 residues), and the mature trypsin. The S. griseus trypsin consists of 223 amino acids with a computed molecular weight of 23,112. The existence of proline at the pro and mature junction suggests that the processing of S. griseus trypsin is non-autocatalytic.