Biochemical characterization of resistance determinants cloned from antibiotic-producing streptomycetes

Cloning of the kanamycin resistance gene from a kanamycin-producing Streptomyces species

A kanamycin-producing strain, Streptomyces kanamyceticus ISP5500, is resistant to kanamycin. A kanamycin resistance determinant was cloned from S. kanamyceticus into Streptomyces lividans 1326, using the plasmid vector pIJ702. The resulting plasmid, pMCP5, could also transform Streptomyces lavendulae S985 and Streptomyces parvulus 2283 to kanamycin resistance. Transformants carrying pMCP5 were markedly more resistant than S. kanamyceticus to the aminoglycoside antibiotics sisomicin, tobramycin, amikacin, and gentamicin. Studies in vitro polyphenylalanine synthesis showed that strains carrying pMCP5 contained kanamycin-resistant ribosomes. However, growing S. kanamyceticus contained kanamycin-sensitive ribosomes. Ribosomes from S. kanamyceticus grown under kanamycin-producing conditions were kanamycin resistant.

Molecular cloning and expression in streptomyces lividans of a hygromycin B phosphotransferase gene from Streptomyces hygroscopicus

The gene encoding the phosphotransferase enzyme that modifies hygromycin B in its producing organism Streptomyces hygroscopicus, has been cloned in the Streptomyces vector pIJ41. Two plasmids, pFM4 and pFM6, containing 2.1 and 19.6 kb inserts of Streptomyces hygroscopicus DNA, respectively, which express the modifying enzyme, have been isolated. A 3.1 kb PstI restriction fragment from pFM4 was inserted in the Streptomyces vector pIJ350 and the resulting plasmids, pMZ11.1 and pMZ11.2, express the hygromycin B-resistance phenotype. The utility of this dominant marker for cloning experiments is discussed in the text.

Genetic and enzymatic basis of hygromycin B resistance in Escherichia coli

A plasmid conferring resistance to the aminocyclitol antibiotic hygromycin B was isolated from Escherichia coli. The gene conferring resistance to this drug was cloned in pBR322, and the gene was localized to a fragment of ca. 1,510 base pairs. Resistance to hygromycin B is determined by an aminocyclitol phosphotransferase that modifies hygromycin B and structurally related antibiotics. The specific modification of hygromycin B is a phosphorylation of the hydroxyl on the 4 position of the cyclitol ring (hyosamine). The presence of the phosphotransferase in E. coli correlates with reduced accumulation of [14C]hygromycin B.

Nucleotide sequence of a streptomycete aminoglycoside phosphotransferase gene and its relationship to phosphotransferases encoded by resistance plasmids

The DNA sequence of an aminoglycoside phosphotransferase gene (aph) from Streptomyces fradiae ATCC 10745 (a neomycin producer) was determined. The gene was localized by in vitro subcloning and insertional inactivation. Molecular weight, amino acid composition, and amino-terminal analysis of the purified aph gene product confirmed the accuracy and position of the aph gene sequence. Pairwise comparisons of S. fradiae aph with the aph genes encoded by bacterial transposons Tn5 and Tn903 showed significant nucleotide and amino acid homologies which indicated a common evolutionary origin for these antibiotic-resistance genes.

Acetylation of puromycin by Streptomyces alboniger the producing organism

Streptomyces alboniger produces the antibiotic puromycin and expresses an enzymic activity which acetylates the drug using acetyl CoA. The N-acetyl-puromycin formed is biologically inactive against protein synthesis in Bacillus subtilis (as assayed in vivo).

Physical analysis of antibiotic-resistance genes from Streptomyces and their use in vector construction

Restriction endonuclease cleavage maps of five DNA fragments carrying genes for neomycin phosphotransferase and neomycin acetyltransferase (from Streptomyces fradiae), viomycin phosphotransferase (from S. vinaceus), and ribosomal methylases determining resistance to thiostrepton (from S. azureus) and MLS antibiotics (from S. erythreus) are described, together with a map for the SLP1.2 Streptomyces plasmid used to isolate the fragments. Construction of a versatile Streptomyces cloning vector (pIJ61) is reported. pIJ61 carries neomycin phosphotransferase and thiostrepton resistance genes and has unique BamHI and PstI sites which will allow clone recognition by insertional inactivation of neomycin resistance; cloning sites for several other endonucleases are also present. pIJ28, a shuttle vector for Streptomyces and E. coli, carries neomycin resistance and the SLP1.2 and pBR322 replicons.

Cloning of antibiotic resistance and nutritional genes in streptomycetes

Methodology which allows consistent shotgun cloning of streptomycete genes is presented. Parameters that increase transformation efficiency of Streptomyces lividans 66 were adjusted to generate reproducibly a population of cloned genes likely to represent the entire genome. Factors which influence the recovery of viable transformants include: growth phase of the mycelium, ionic and osmotic characteristics of the medium during protoplast formation and transformation, and moisture content and protoplast density during regeneration. A modified transformation procedure was devised which increased transformation frequency more than 20-fold (allowing up to 10(7) primary transformants per microgram of SLP1.2 covalently closed circular DNA) and greatly facilitated the cloning of drug resistance genes and biosynthetic genes, using one of two plasmid vectors. Viomycin resistance genes on BamHI or PstI fragments were cloned from S. vinaceus genomic DNA into S. lividans, using the SLP1.2 vector. At least three different S. vinaceus BamHI fragments (1.9, 5.8, or 8.5 kilobases) confer viomycin resistance; only one PstI fragment (4.3 kilobases) was found. Recombinant plasmids were all able to produce lethal zygosis and to be transferred by conjugation within S. lividans. SCP2 was used to clone S. coelicolor A3(2) genes that "complemented" the auxotrophic mutation hisD3, argA1, or guaA1. Recombinant DNA technology can now be applied to economically and academically interesting problems unique to streptomycete molecular biology.