Low temperature adaptation of hyperthermophile

热球菌和热球菌属热球菌目，具有不同的生理特征。它们生长在接近或高于100℃的温度下，是严格意义上的厌氧异养生物，利用各种碳底物，如多肽和/或碳水化合物。唯一的区别是生长温度范围不同。例如，热球菌属的最低生长温度。(例如柯达卡氏热球菌，60℃)普遍低于热球菌。(P.abyssi，67℃；P.Furiosus，70℃；P.horikoshii，80℃)。柯达卡氏热球菌具有单一的环状基因组，有747个基因是柯达卡氏热球菌中所特有的，这些基因在热球菌属中没有发现。这些基因中的一些被认为与柯达卡拉毛虫的低温生存有关。转录组和蛋白质组的研究表明，一些基因在低温环境中被特异地诱导。其中，我们主要研究了伴侣蛋白CpkA和RNAhelicase(TK0306)及其对…的诱导作用分析了更多的文件。低温诱导伴侣蛋白cpkA的表达在转录后水平上受到调控。相反，高温诱导的伴侣蛋白cpkB在转录水平上被调控。当我们比较cpkA和cpkB的启动子序列时，只观察到微小的差异，这表明这两个基因是从同一个共同的祖先进化而来的，只有cpkA在进化过程中获得了低温诱导机制。至于RNA解旋酶，它在转录水平上受到调控。RNAhelicase在50℃时酶活最高。这是不寻常的，因为Tkodakarasis不是在这种温度下生长的。RNA解旋酶似乎只有在低温环境中才能存活。还需要进一步的研究来证实这一想法。除这两个基因外，还研究了异戊烯基二磷酸异构酶、氨基葡萄糖-6-磷酸脱氨酶、甲基鸟嘌呤-DNA甲基转移酶和归巢酶的酶学特性。较少

Both Thermococcus and Pyrococcus species belong to the Thermococcales order and share various physiological features. They grow near or above at 100℃ and are strictly anaerobic heterotrophs that utilize a variety of carbon substrates, such as peptides and/or carbohydrates. The unique difference is the growth temperature range. For example, the minimum growth temperatures of Thermococcus spp. (ex. Thermococcus kodakaraensis, 60℃) are generally lower than those of Pyrococcus spp. (P.abyssi, 67℃ ; P.furiosus, 70℃ ; P.horikoshii, 80℃). Thermococcus kodakarensis possesses a single circular genome and 747 genes are unique in T.kodakaraensis that are not identified in Pyrococcus spp. Some of these genes are considered to be involved in low temperature survival in T. kodakaraensis. Transcriptome and proteome studies revealed that some genes are induced specifically at low temperature environment. Among them, we mainly focused on chaperonin CpkA and RNA helicase (Tk0306) and their induction pro … More files were analyzed. The expression of low temperature inducible chaperonin cpkA was regulated at the post-transcriptional level. In contrast, high temperature inducible chaperonin cpkB was regulated at the level of transcription. When we compare promoter sequences of cpkA and cpkB, only slight difference was observed, suggesting that these genes were evolved from the same common ancestor and only cpkA acquired low temperature inducible mechanism in the course of evolution. As for RNA helicase, it was regulated at the level of transcription. RNA helicase showed highest enzymatic activity at 50℃. It is unusual because Tkodakaraensis does not grow at the temperature. The RNA helicase seems functional in T. kodakaraensis only to survival at low temperature environments. Further study is needed to confirm the idea. Besides these two genes, enzymatic characteristics for isopentenyl diphasphate isomerase, glucosamine-6-phosphate deaminase, methylguanine-DNA methyltransferase and homing endnuclasell were examined. Less