DNA Recombination of Thermophiles

在生物体中，基因重组与DNA损伤有关。DNA损伤通常是由于基因重组、DNA复制和其他过程而产生的。在原核生物中，大约有50种酶参与DNA修复反应。从嗜热菌（包括超嗜热菌）中克隆了DNA修复相关基因，包括重组修复酶（RecA、RuvA、RuvB、RuvC、ssb）、碱基切除修复酶（MutM、MutY、EndoIII、EndoV）、核苷酸切除修复酶（UvrA、UvrB、UvrC、UvrD）、错配修复酶（MutS、MutL）、光裂合酶、DNA聚合酶I和连接酶。这些DNA修复系统中的大多数是许多生物体所共有的，包括智人。这些嗜热酶，如预期的那样，是稳定的。还发现通过用蛋白酶部分消化可以容易地分离各个蛋白质的结构域。一些修复酶，包括MutM，UvrB，和光解酶，已结晶，并已确定其三维结构。这些嗜热酶已适应高温。某些超高温修复酶在75℃以上时构象发生显著变化，活性增强

In living organisms, genetic recombination is related to the DNA damage. DNA damage often arises as a result of genetic recombination, DNA replication, and other processes. In prokaryotes, about fifty enzymes participate in the DNA repair reactions. From thermophilic bacteria including hyperthermophile, we have cloned the DNA-repair related genes, which include recombinational repair enzymes (RecA, RuvA, RuvB, RuvC, ssb), base excision repair enzymes (MutM, MutY, EndoIII, EndoV), nucleotide excision repair enzymes (UvrA, UvrB, UvrC, UvrD), mismatch repair-enzymes (MutS, MutL), photolyase, and DNA polymerase I and ligase. Most of these DNA repair systems are common to many organisms, including those of Homo sapiens. These thermophilic enzymes, as expected, were stable. It was also found that the domains of the respective proteins can be easily isolated by partial digestion with protease. Some repair enzymes, including MutM, UvrB, and photolyase, have been crystallized and their three-dimensional structures have been determined. These thermophilic enzymes have been adapted to high temperatures. Some hyperthermophilic repair enzymes dramatically changed its conformation and increased the activity above 75℃