Halophilic adaptation of protein-DNA interactions
Halophilic adaptation of protein-DNA interactions
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DOI：
10.1042/bst0310677
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发表时间：
2003-06-01
影响因子：
3.9
通讯作者：
Ladbury, JE
中科院分区：
文献类型：
--
作者：
Bergqvist, S;Williams, MA;Ladbury, JE
沃氏热球菌(PW)是一种适应高温、高盐环境的古生物。热力学数据表明，该生物体的TATA盒结合蛋白(TBP)与DNA之间的相互作用具有与中温生物中相同的相互作用完全不同的特征。在PwTBP的情况下，其与DNA相互作用的亲和力随着盐浓度的增加而增加。在所有已知的中温蛋白质-DNA相互作用中都观察到了相反的效果。这种嗜盐行为可以归因于阳离子被隔离到蛋白质-DNA复合体中。通过突变PwTBP DNA结合位点上的残基，可以去除潜在的阳离子相互作用部位。这些突变对结合特性有很大影响，PwTBP-DNA相互作用的嗜盐性质可以逆转，只有三个突变就能使其类似于中温细菌。存在于不同环境中的生物体中功能同源蛋白的基因表明，适应通常伴随着现有蛋白质的突变。然而，在进化过程中发生的众多变化中，任何个体残基对表型特征的重要性通常很难评估。由于该蛋白的嗜盐性仅可归因于三个突变，这表明重要的嗜盐性表型可以在进化过程中迅速获得。
Pyrococcus woesei (Pw) is an archaeal organism adapted to living in conditions of elevated salt and temperature. Thermodynamic data reveal that the interaction between the TATA-box-binding protein (TBP) from this organism and DNA has an entirely different character to the same interaction in mesophilic counterparts. In the case of the PwTBP, the affinity of its interaction with DNA increases with increasing salt concentration. The opposite effect is observed in all known mesophilic protein-DNA interactions. The halophilic behaviour can be attributed to sequestration of cations into the protein-DNA complex. By mutating residues in the PwTBP DNA-binding site, potential sites of cation interaction can be removed. These mutations have a significant effect on the binding characteristics, and the halophilic nature of the PwTBP-DNA interaction can be reversed, and made to resemble that of a mesophile, in just three mutations. The genes of functionally homologous proteins in organisms existing in different environments show that adaptation is most often accompanied by mutation of an existing protein. However, the importance of any individual residue to a phenotypic characteristic is usually difficult to assess amongst the multitude of changes that occur over evolutionary time. Since the halophilic nature of this protein can be attributed to only three mutations, this reveals that the important phenotype of halophilicity could be rapidly acquired in evolutionary time.