期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：8
页码：2141-2144
DOI：10.1073/pnas.69.8.2141
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The 16S RNA dissociated from 30S ribosomal subunits of Escherichia coli strains either sensitive or resistant to streptomycin contains the attachment sites for two streptomycin molecules, as does the undissociated particle from a streptomycin-sensitive strain. Since no streptomycin binds to undissociated 30S subunits from a streptomycin-resistant strain, it is suggested that protein P10, specified by the strA locus--known to be responsible for drug sensitivity--controls the availability to streptomycin of the attachment sites. These sites remain exposed in the strA+ wild-type, and become masked in strA streptomycin-resistant mutants. The 16S RNA molecule binds streptomycin specifically; it binds two drug molecules in its native state, binds many more after its secondary structure is unfolded by melting out, and again binds two molecules after reannealing. The binding is stable to exhaustive dialysis, but it is reversed by exposure of the streptomycin-RNA complex to high-salt concentration. The complex can not be used to reconstitute functional ribosomes, but the 16S RNA reacquires this property after streptomycin elimination. The biological significance of this stable streptomycin binding is questioned, since in strA mutants exhibiting phenotypic masking, exposure to streptomycin induces a modified 30S behavior that persists even after streptomycin has been dialyzed away, and is reversed only by exposure of the modified RNA to high-salt concentration.
关键词：streptomycin-ribosomal binding ; antibiotic ; protein synthesis ; 16S RNA ; protein P10
