Ueda K, Seki T, Kudo T, Yoshida T, Kataoka M
International Center for Biotechnology, Osaka University, Yamada-oka, Suita, Osaka 565, Japan.
J Bacteriol. 1999 Jan;181(1):78-82. doi: 10.1128/JB.181.1.78-82.1999.
To investigate the frequency of heterogeneity among the multiple 16S rRNA genes within a single microorganism, we determined directly the 120-bp nucleotide sequences containing the hypervariable alpha region of the 16S rRNA gene from 475 Streptomyces strains. Display of the direct sequencing patterns revealed the existence of 136 heterogeneous loci among a total of 33 strains. The heterogeneous loci were detected only in the stem region designated helix 10. All of the substitutions conserved the relevant secondary structure. The 33 strains were divided into two groups: one group, including 22 strains, had less than two heterogeneous bases; the other group, including 11 strains, had five or more heterogeneous bases. The two groups were different in their combinations of heterogeneous bases. The former mainly contained transitional substitutions, and the latter was mainly composed of transversional substitutions, suggesting that at least two mechanisms, possibly misincorporation during DNA replication and horizontal gene transfer, cause rRNA heterogeneity.
为了研究单个微生物内多个16S rRNA基因间的异质性频率，我们直接测定了475株链霉菌16S rRNA基因高变α区域的120个碱基的核苷酸序列。直接测序图谱显示，在总共33株菌株中存在136个异质位点。异质位点仅在指定为螺旋10的茎区被检测到。所有的替换都保留了相关的二级结构。这33株菌株被分为两组：一组包括22株，其异质碱基少于两个；另一组包括11株，其异质碱基有五个或更多。两组的异质碱基组合不同。前者主要包含转换替换，后者主要由颠换替换组成，这表明至少有两种机制，可能是DNA复制过程中的错误掺入和水平基因转移，导致了rRNA异质性。
