Enzymatic synthesis of aminoglycoside antibiotics: novel adenosylmethionine:2-deoxystreptamine N-methyltransferase activities in hygromycin B- and spectinomycin-producing Streptomyces spp. and uses of the methylated products.
Aminocyclitols structurally related to streptamine, a 1,3-diaminocyclitol, are common components of the RNA-binding aminoglycoside antibiotics. The respective aminocyclitol cores of hygromycin B and spectinomycin are N(3)-methyl-2-deoxy-D-streptamine and N(1),N(3)-dimethyl-2-epi-streptamine. Adenosyl[methyl-(14)C]methionine:2-deoxystreptamine N-methyltransferase activities were detected in extracts of early-stationary-phase mycelia of the hygromycin B producer Streptomyces hygroscopicus subsp. hygroscopicus ATCC 27438 and the spectinomycin producer Streptomyces flavopersicus ATCC 19756. Extracts of both strains methylated the N(1)- and N(3)-amino groups of 2-deoxystreptamine, streptamine, and 2-epi-streptamine; the N(1)-amino group of N(3)-methyl-2-deoxy-D-streptamine, and the N(3)-amino group of N(1)-ethyl-2-deoxy-D-streptamine, the semisynthetic aminocyclitol of netilmicin. The mono[(14)C]methyl derivatives of 2-deoxystreptamine, streptamine, and 2-epi-streptamine were excellent substrates for L-glutamine:aminocyclitol aminotransferase and thereby provided a sensitive assay for derepression of this key enzyme, a generic biosynthetic marker that we have shown to be the only enzyme common to the biosyntheses of all major aminoglycoside antibiotics. Other prospective uses for these methyl-labeled 2-deoxystreptamine analogs are also described.
Walker
James B
JB
Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77251, USA. bioc@rice.edu
D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D002250:Carbon Radioisotopes; D006595:Hexosamines / Q000378:metabolism; D006921:Hygromycin B / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D010766:Phosphorylation; D000198:Spectinomycin / Q000378:metabolism*; D013302:Streptomyces / Q000201:enzymology / Q000378:metabolism*; D013379:Substrate Specificity; D000637:Transaminases / Q000378:metabolism
D000900:Anti-Bacterial Agents; D002250:Carbon Radioisotopes; D006595:Hexosamines; D006921:Hygromycin B; C002980:streptamine; D000198:Spectinomycin; D008780:Methyltransferases; D000637:Transaminases; C007265:2-deoxystreptamine