Roy Mousam, Bhakta Koustav, Ghosh Abhrajyoti
Department of Biochemistry, Bose Institute, Kolkata, India.
Front Mol Biosci. 2022 May 12;9:832160. doi: 10.3389/fmolb.2022.832160. eCollection 2022.
Small heat shock proteins (sHsp) are a ubiquitous group of ATP-independent chaperones found in all three domains of life. Although sHsps in bacteria and eukaryotes have been studied extensively, little information was available on their archaeal homologs until recently. Interestingly, archaeal heat shock machinery is strikingly simplified, offering a minimal repertoire of heat shock proteins to mitigate heat stress. sHsps play a crucial role in preventing protein aggregation and holding unfolded protein substrates in a folding-competent form. Besides protein aggregation protection, archaeal sHsps have been shown recently to stabilize membranes and contribute to transferring captured substrate proteins to chaperonin for refolding. Furthermore, recent studies on archaeal sHsps have shown that environment-induced oligomeric plasticity plays a crucial role in maintaining their functional form. Despite being prokaryotes, the archaeal heat shock protein repository shares several features with its highly sophisticated eukaryotic counterpart. The minimal nature of the archaeal heat shock protein repository offers ample scope to explore the function and regulation of heat shock protein(s) to shed light on their evolution. Moreover, similar structural dynamics of archaeal and human sHsps have made the former an excellent system to study different chaperonopathies since archaeal sHsps are more stable under experiments.
小热休克蛋白（sHsp）是一类普遍存在的不依赖ATP的分子伴侣，存在于生命的所有三个域中。尽管细菌和真核生物中的sHsp已得到广泛研究，但直到最近，关于它们在古菌中的同源物的信息仍然很少。有趣的是，古菌的热休克机制显著简化，提供了最少的热休克蛋白库来减轻热应激。sHsp在防止蛋白质聚集以及将未折叠的蛋白质底物保持在具有折叠能力的形式方面起着关键作用。除了保护蛋白质不聚集外，最近还发现古菌sHsp可以稳定细胞膜，并有助于将捕获的底物蛋白转移到伴侣蛋白中进行重新折叠。此外，最近对古菌sHsp的研究表明，环境诱导的寡聚可塑性在维持其功能形式方面起着关键作用。尽管古菌是原核生物，但其热休克蛋白库与高度复杂的真核生物热休克蛋白库有几个共同特征。古菌热休克蛋白库的简单性为探索热休克蛋白的功能和调控提供了广阔的空间，有助于阐明其进化过程。此外，古菌和人类sHsp相似的结构动力学使前者成为研究不同伴侣蛋白病的优秀系统，因为古菌sHsp在实验中更稳定。
