The FtsH protease is involved in development, stress response and heat shock control in Caulobacter crescentus
The FtsH protease is involved in development, stress response and heat shock control in Caulobacter crescentus
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DOI：
10.1046/j.1365-2958.2002.02887.x
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发表时间：
2002-04-01
影响因子：
3.6
通讯作者：
Jenal, U
中科院分区：
文献类型：
--
作者：
Fischer, B;Rummel, G;Jenal, U
新月柄杆菌的ftsH基因已被分离并鉴定为该生物体的一般应激反应的组成部分。In C. crescentus，ftsH表达在温度升高后和稳定期短暂诱导。与此相一致，丧失FtsH蛋白酶的突变体在正常生长条件下是可行的，但对升高的温度、增加的盐浓度或抗生素的存在高度敏感。过量表达ftsH导致盐耐受性增加，但不耐热，强调了FtsH蛋白酶在应激反应中的重要性。缺乏FtsH的突变体不能在稳定期进行形态和生理适应，并且在饥饿时，比含有FtsH的细胞经历了更明显的活力丧失。此外，缺乏FtsH的细胞具有增加的热休克σ因子σ的细胞浓度（32），这表明，如在大肠杆菌中，FtsH蛋白酶参与C.新月体热休克反应与此一致，转录的热诱导σ（32）依赖性基因dnaK在正常温度下，当FtsH是不存在的去抑制。相比之下，groEL基因，这是控制在热应激的sigma（32）和HcrA/CIRCE机制，不去阻遏在ftsH突变体。最后，FtsH参与了C.新月体发育和细胞周期调控。ftsH突变体不能有效地合成茎，并具有严重的细胞分裂表型。在没有FtsH的情况下，群集细胞比FtsH存在时更快地分化成柄细胞，即使在这些条件下整个细胞周期更长。因此，FtsH蛋白酶直接或间接地参与了固有的生物钟机制，该机制控制着C. crescentus。
The ftsH gene of Caulobacter crescentus has been isolated and identified as a component of the general stress response of this organism. In C. crescentus , ftsH expression is transiently induced after temperature upshift and in stationary phase. Consistent with this, mutants deprived of the FtsH protease are viable at normal growth conditions, but are highly sensitive to elevated temperature, increased salt concentration or the presence of antibiotics. Overexpression of ftsH resulted in an increased salt but not thermotolerance, emphasizing the importance of the FtsH protease in stress response. Mutants lacking FtsH were unable to undergo morphological and physiological adaptation in stationary phase and, upon starvation, experienced a more pronounced loss of viability than cells containing FtsH. In addition, cells lacking FtsH had an increased cellular concentration of the heat shock sigma factor sigma(32) , indicating that, as in Escherichia coli , the FtsH protease is involved in the control of the C. crescentus heat shock response. In agreement with this, transcription of the heat-induced sigma(32) -dependent gene dnaK was derepressed at normal temperature when FtsH was absent. In contrast, the groEL gene, which is controlled in response to heat stress by both sigma(32) and a HcrA/CIRCE mechanism, was not derepressed in an ftsH mutant. Finally, FtsH is involved in C. crescentus development and cell cycle control. ftsH mutants were unable to synthesize stalks efficiently and had a severe cell division phenotype. In the absence of FtsH, swarmer cells differentiated into stalked cells faster than when FtsH was present, even though the entire cell cycle was longer under these conditions. Thus, directly or indirectly, the FtsH protease is involved in the inherent biological clock mechanism, which controls the timing of cell differentiation in C. crescentus.