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PubMed2001

Streptomycin-resistant and streptomycin-dependent mutants of the extreme thermophile Thermus thermophilus.

We have isolated spontaneous streptomycin-resistant, streptomycin-dependent and streptomycin-pseudo-dependent mutants of the thermophilic bacterium Thermus thermophilus IB-21. All mutant phenotypes were found to result from single amino acid substitutions located in the rpsL gene encoding ribosomal protein S12. Spontaneous suppressors of streptomycin dependence were also readily isolated. Thermus rpsL mutations were found to be very similar to rpsL mutations identified in mesophilic organisms. This similarity affords greater confidence in the utility of the crystal structures of Thermus ribosomes to interpret biochemical and genetic data obtained with Escherichia coli ribosomes. In the X-ray crystal structure of the T. thermophilus HB8 30 S subunit, the mutated residues are located in close proximity to one another and to helices 18, 27 and 44 of 16 S rRNA. X-ray crystallographic analysis of ribosomes from streptomycin-resistant, streptomycin-pseudo-dependent and streptomycin-dependent mutants described here is expected to reveal fundamental insights into the mechanism of tRNA selection, translocation, and conformational dynamics of the ribosome.

Alleles↗
PubMed1983

Purification and characterization of streptomycin 6-kinase, an enzyme implicated in self-protection of a streptomycin-producing micro-organism.

Streptomycin 6-kinase of the streptomycin-producing strain Streptomyces griseus HUT 6037 was purified by fractionation with (NH4)2SO4 and chromatography on DEAE-Sephadex A-25, hydroxyapatite and Sephadex G-100. After PAGE of the final fraction, a protein band corresponding to streptomycin 6-kinase was detected, together with a less intense band having no enzyme activity. Molecular weights determined by SDS-PAGE and by Sephadex G-100 chromatography were about 36000 and 38000, respectively, suggesting that the enzyme was a monomer. The isoelectric point of the enzyme was pH 6.6. Among the nucleoside 5'-triphosphates tested, ATP was the preferred phosphoryl donor. The Km values for streptomycin and ATP were 3.5 mM and 0.4 mM, respectively. The enzyme activity was strongly inhibited by EDTA and AgNO3. It was shown by using an in vitro protein-synthesizing system that purified streptomycin 6-kinase could protect polyphenylalanine synthesis of the streptomycin-susceptible S. griseus strain KSN from inhibition by streptomycin.

Kinetics↗
PubMed1990

[Cross-resistance relationship between streptomycin and kanamycin resistances in Mycobacterium smegmatis (strain Jucho)--comparison of the development patterns of resistances to streptomycin and kanamycin among Mycobacterium tuberculosis, Mycobacterium avium complex, and Mycobacterium smegmatis].

The resistance development pattern of Mycobacterium smegmatis strain 17023 (Jucho) to streptomycin and kanamycin was studied. The medium used was Ogawa egg medium, and the level of resistance was determined for each clone derived from single colony by the 'actual count' method. Hence, the resistance level was estimated as the highest concentration of drugs, in which small inocula consisting of 20 to 100 colony-forming units could grow after seven days incubation. Only one type of resistance mutants resistant to more than 1,000 micrograms/ml streptomycin was isolated and these mutants were also resistant to 8 micrograms/ml kanamycin. On the other hand, only one type of kanamycin-resistant mutants resistant to 8 micrograms/ml kanamycin was isolated and these mutants were also resistant to more than 1,000 micrograms/ml streptomycin. Accordingly, there was a complete cross-resistance relationship between streptomycin and kanamycin resistances. Therefore, there existed only one phenotype, which is simultaneously resistant to streptomycin and kanamycin. The mutants occurred at a rate of about 2 x 10(-8) per viable bacterial population of the parent strain. Streptomycin-dependent mutants occurred at a rate of about 2 x 10(-9). The number of resistant phenotypes to streptomycin and kanamycin was only one in M. smegmatis, while it was five in M. tuberculosis and 2 or 3 in M. avium complex (Tsukamura, M. and Mizuno, S.: J. Gen. Microbiol. 88: 269-274, 1975; Tsukamura, M.: Kekkaku 62: 445-458, 1987). The simplicity of the resistance system of M. smegmatis suggests that this organism is evolutionally primitive in the world of mycobacteria.

Drug Resistance, Microbial↗
PubMed2005

Enzyme immunoassays for the analysis of streptomycin in milk, serum and water: development and assessment of a polyclonal antiserum and assay procedures using novel streptomycin derivatives.

A polyclonal antiserum to streptomycin was generated in sheep using a streptomycin-bovine serum albumin conjugate as immunogen. Streptomycin was linked to the carrier protein with cyanuric chloride using a new two-step conjugation method. Plate coating antigen conjugates of streptomycin and gelatine were prepared using either cyanuric chloride (homologous bridge) or 1,4-butanediol diglycidyl ether to provide an heterologous complex. The reagents enabled the generation of a specific antiserum with a titre of 1/40,000 and the development of a sensitive ELISA method suitable for the measurement of streptomycin sulfate in milk, serum and water samples. A minimum detection value of 1 ng mL(-1) and a dynamic range of 1 to 200 ng mL(-1) were demonstrated in the three matrices. No detectable cross reactivity with any of the common aminoglycosides was found except the related dihydrostreptomycin which gave a 75% cross reaction value. The details of the preparation of the hapten-protein conjugates, characterisation of the antiserum and assay construction and assessment methods are presented. The introduction of new coupling methods and antibody assessment provide improved basic methodologies necessary for the advancement of immuno-analysis of streptomycin, one of the most widely used antimicrobial substances.

Animals↗
PubMed1974

Mutations in Escherichia coli K-12 decreasing the rate of streptomycin uptake: synergism with R-factor-mediated capacity to inactivate streptomycin.

Escherichia coli K-12 carrying the R-factor R1 or R6K is resistant to streptomycin. The resistance is due to R-factor-coded enzymes that metabolize the drug. Streptomycin can be inactivated in two ways, either by adenylylation or by phosphorylation; both reactions require adenosine 5'-triphosphate. In this work we show that the R-factor R1 codes for an enzyme that adenylylates streptomycin and that the enzyme activity is located in the periplasmic volume, whereas the R-factor R6K codes for a streptomycin phosphorylase, which is mainly cytoplasmic. From a strain without any R-factor or carrying different R-factors, mutants were isolated that are 10 times more resistant to streptomycin than the parent strains. This increased resistance is not due to increased amounts of metabolizing enzymes. The mutants have a decreased rate of uptake of streptomycin and an altered response to other antibacterial agents as well. The mutations are located on the chromosome and not on the plasmid. It is likely that the mutations cause changes in the outer layers of the cell envelope and that the increased resistance is due to the synergistic effect of an efficient penetration barrier and a low activity of inactivating enzyme.

Drug Resistance, Microbial↗
PubMed1981

[Antibiotic relationship of streptomycin-dependent and streptomycin-resistant Escherichia coli mutants pathogenic for poultry].

Studied was the reaction streptomycin-dependent and streptomycin-resistant mutants and their revertants of the Escherichia coli strains 078:K80, 02:K1, and 0111:K58 to the following, practically important antibiotics: rifampicin, novobiocin, chloramphenicol, and penicillin. The study made use of mutants of both smooth (S) and rough (R) form obtained through induced mutagenesis effected by means of nitrosoguanidine and nitrous acid. The method of serial dilution of antibiotics and that of dynamic recording of their action through automatic biophotometry were employed. Negligible differences were established in the behaviour of the various groups of organisms. The streptomycin - dependent mutants retained unchanged the reaction of the initial strains to the antibiotics. The revertants showed high level of of resistance to streptomycin and by their behaviour they were closer to the streptomycin - resistant mutants than to the initial strains. In connection with this the probability is discussed of the "suppressor" origin of the streptomycin-dependent mutants.

Animals↗
PubMed1979

Streptomycin resistance in a streptomycin-producing microorganism.

Cell-free extracts of Streptomyces bikiniensis contain an adenosine 5'-triphosphate-dependent kinase which inactivates streptomycin (Sm) and dihydrostreptomycin by phosphorylation. The products have been identified as streptomycin 6-phosphate and dihydrostreptomycin 6-phosphate. Activity was not present in logarithmic-phase cells, which were susceptible to 25 mug of Sm per ml. In stationary-phase cells, activity appeared 12 h before detectable Sm in the medium. These cells were resistant to more than 200 mug of Sm per ml. Certain S. bikiniensis isolates selected from cultures treated with acriflavine or ethidium bromide lost the ability to produce Sm and became susceptible to 10 mug of Sm per ml throughout their growth. Cell-free extracts of the dye-treated isolates did not inactivate Sm and lacked streptomycin kinase activity at all stages in development. Ribosomes from resistant cells bound the same amount of [(3)H]dihydrostreptomycin as ribosomes from susceptible cells, and there was no correlation between the uptake of [(3)H]dihydrostreptomycin and resistance. The Sm-inactivating enzyme was identified as streptomycin-6-kinase. These results suggest that phosphorylation by streptomycin-6-kinase is a major factor in resistance in S. bikiniensis.

Drug Resistance, Microbial↗