Degradation of carboxy-terminal-tagged cytoplasmic proteins by the Escherichia coli protease HflB (FtsH)
Degradation of carboxy-terminal-tagged cytoplasmic proteins by the Escherichia coli protease HflB (FtsH)
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DOI：
10.1101/gad.12.9.1348
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发表时间：
1998-05-01
影响因子：
10.5
通讯作者：
D'Ari, R
中科院分区：
文献类型：
--
作者：
Herman, C;Thévenet, D;D'Ari, R
具有短非极性羧基末端的蛋白质在大肠杆菌中是不稳定的。这种蛋白水解途径用于处理由截断的mRNA分子合成的多肽。这些蛋白质通过涉及10Sa （SsrA）稳定RNA的机制，用il -氨基酸非极性不稳定尾部标记，然后降解。我们在这里表明，atp依赖性锌蛋白酶HflB （FtsH）参与了lambda cI抑制因子氨基末端结构域的四个不稳定衍生物的降解：三个具有非极性五肽末端（cI104, cI105, cI108）和一个具有SsrA标签（cI-SsrA）。cI105和cI-SsrA也被clpp依赖性蛋白酶降解。ClpP的损失可以通过过量生产HflB来弥补。在体外系统中，cI108和cI-SsrA被HflB以能量依赖的反应降解，表明HflB本身识别羧基端。这些结果建立了通过HflB和Clp蛋白酶去除异常细胞质蛋白的尾巴特异性途径。
Proteins with short nonpolar carboxyl termini are unstable in Escherichia coli. This proteolytic pathway is used to dispose of polypeptides synthesized from truncated mRNA molecules. Such proteins are tagged with an Il-amino-acid nonpolar destabilizing tail via a mechanism involving the 10Sa (SsrA) stable RNA and then degraded. We show here that the ATP-dependent zinc protease HflB (FtsH) is involved in the degradation of four unstable derivatives of the amino-terminal domain of the lambda cI repressor: three with nonpolar pentapeptide tails (cI104, cI105, cI108) and one with the SsrA tag (cI-SsrA). cI105 and cI-SsrA are also degraded by the ClpP-dependent proteases. Loss of ClpP can be compensated for by overproducing HflB. In an in vitro system, cI108 and cI-SsrA are degraded by HflB in an energy-dependent reaction, indicating that HflB itself recognizes the carboxyl terminus. These results establish a tail-specific pathway for removing abnormal cytoplasmic proteins via the HflB and Clp proteases.