Apirion D, Schlessinger D
Proc Natl Acad Sci U S A. 1969 Jul;63(3):794-9. doi: 10.1073/pnas.63.3.794.
Ribosomes are made up of parts that interact so strongly that a mutation in one of them can mask the effect of mutation in another. For example, when a mutation to neomycin resistance, which is a ribosome mutation, is introduced into cells carrying a ribosome mutation to spectinomycin resistance, some of the doubly mutant strains were phenotypically sensitive to spectinomycin, even though the mutation to spectinomycin resistance is still intact and recoverable in appropriate crosses. The neomycin mutant alleles that cause masking were shown by genetic tests to be in an identified locus that affects ribosomes. Protein synthesis in cell-free extracts of a double mutant strain was as sensitive to the action of spectinomycin as was the extract of the doubly sensitive parental strain. Thus, the masking effect of neomycin mutations on the spectinomycin mutation is exerted at the level of the ribosomes.We conclude that the genetic analysis of an organelle like the ribosome is likely to be severely complicated by pleiotropic effects and by interactions among its component parts and that the ribosomal binding sites for spectinomycin and neomycin are partially interdependent. These results suggest that the function of the ribosome requires a very precise conformation of all its elements, some of which are interdependent. Modification in one element can thus alter the function of another or even render the entire structure nonfunctional.
核糖体由相互作用非常强烈的部分组成，以至于其中一个部分发生突变可能会掩盖另一个部分突变的影响。例如，当将对新霉素耐药的突变（这是一种核糖体突变）引入携带对壮观霉素耐药的核糖体突变的细胞中时，一些双突变菌株在表型上对壮观霉素敏感，尽管对壮观霉素耐药的突变仍然完整，并且在适当的杂交中可以恢复。通过遗传测试表明，导致掩盖现象的新霉素突变等位基因位于一个影响核糖体的已确定基因座中。双突变菌株的无细胞提取物中的蛋白质合成对壮观霉素作用的敏感性与双敏感亲本菌株的提取物相同。因此，新霉素突变对壮观霉素突变的掩盖作用是在核糖体水平上发挥的。我们得出结论，像核糖体这样的细胞器的遗传分析可能会因多效性效应及其组成部分之间的相互作用而严重复杂化，并且壮观霉素和新霉素的核糖体结合位点部分相互依赖。这些结果表明，核糖体的功能需要其所有元件都具有非常精确的构象，其中一些元件是相互依赖的。因此，一个元件的修饰可以改变另一个元件的功能，甚至使整个结构失去功能。
