Disruption of rpmJ encoding ribosomal protein L36 decreases the expression of secY upstream of the spc operon and inhibits protein translocation in Escherichia coli
Disruption of rpmJ encoding ribosomal protein L36 decreases the expression of secY upstream of the spc operon and inhibits protein translocation in Escherichia coli
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DOI：
10.1271/bbb.69.1595
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发表时间：
2005-08-01
影响因子：
1.6
通讯作者：
Tokuda, H
中科院分区：
文献类型：
--
作者：
Ikegami, A;Nishiyama, K;Tokuda, H
大肠杆菌的spc操纵子编码11种核糖体蛋白和SecY。 secY 基因和编码核糖体蛋白 L36 的下游 rpmJ 位于 spc 操纵子启动子的远端。有人建议，SecY mRNA 的稳定性取决于 rpmJ，除非将 p 独立终止子插入到 secY 的紧下游。此外，有人认为RpmJ对于大肠杆菌来说是可有可无的。我们分别用编码负责四环素抗性的膜蛋白的 tetA 和编码细胞质氯霉素乙酰转移酶的 cat 替换 rpmJ，构建了 rpmJ 无效菌株 AY101 (Delta rpmj::tetA) 和 AY201 (Delta rpmJ::cat)。 RpmJ 的消耗不会抑制蛋白质合成，而 AY101 的生长在高温下有缺陷。即使 p 独立终止子直接插入 secY 下游，两种破坏子中 SecY mRNA 的水平仍显着下降。破坏子中缺少一些周质蛋白，同时内膜中噬菌体休克蛋白的量增加。这些由 rpmJ 无效突变引起的表型可以通过携带 secY 的质粒纠正，但不能通过携带 rpmJ 的质粒纠正。
The spc operon of Escherichia coli encodes 11 ribosomal proteins and SecY. The secY gene and downstream rpmJ encoding a ribosomal protein, L36, are located distal to the promoter of the spc operon. It has been suggested that the stability of SecY mRNA depends on rpmJ unless a p-independent terminator is inserted immediately downstream of secY. Moreover, it has been suggested that RpmJ is dispensable for E. coli. We constructed rpmJ null strains, AY101 (Delta rpmj::tetA) and AY201 (Delta rpmJ::cat), by replacing rpmJ with tetA, which encodes a membrane protein responsible for tetracycline-resistance, and cat, which encodes a cytoplasmic chloramphenicol acetyltransferase, respectively. Depletion of RpmJ did not inhibit protein synthesis, whereas the growth of AY101 was defective at high temperatures. The level of SecY mRNA decreased significantly in both disruptants even though the p-independent terminator was inserted immediately downstream of secY. Some periplasmic proteins were missing in the disruptants with a concomitant increase in the amount of phage shock protein in the inner membrane. These phenotypes caused by the rpmJ null mutation were corrected by a plasmid carrying secY, but not by one carrying rpmJ.