Department of Biology, University of Naples Federico II, Napoli, Italy.
Institute of Biostructure and Bioimaging, CNR, Napoli, Italy.
Int J Biol Macromol. 2019 Oct 1;138:1056-1063. doi: 10.1016/j.ijbiomac.2019.07.174. Epub 2019 Jul 26.
The transcription factors of the ArsR/SmtB family are widespread within the bacterial and archaeal kingdoms. They are transcriptional repressors able to sense a variety of metals and undergo allosteric conformational changes upon metal binding, resulting in derepression of genes involved in detoxification. So far, the molecular determinants of specificity, selectivity, and metal binding mechanism have been scarcely investigated in thermophilic microorganisms. TtSmtB, the only ArsR/SmtB member present in the genome of Thermus thermophilus HB27, was chosen as a model to shed light into such molecular mechanisms at high temperature. In the present study, using a multidisciplinary approach, a structural and functional characterization of the protein was performed focusing on its metal interaction and chemical-physical stability. Our data demonstrate that TtSmtB has two distinct metal binding sites per monomer and interacts with di-tri-penta-valent ions with different affinity. Detailed knowledge at molecular level of protein-metal interaction is remarkable to design metal binding domains as scaffolds in metal-based therapies as well as in metal biorecovery or biosensing in the environment.
ArsR/SmtB 家族的转录因子广泛存在于细菌和古菌王国中。它们是转录抑制剂，能够感知多种金属，并在金属结合时发生变构构象变化，导致解毒基因的去抑制。到目前为止，在嗜热微生物中，特异性、选择性和金属结合机制的分子决定因素还很少被研究。Thermus thermophilus HB27 基因组中唯一的 ArsR/SmtB 成员 TtSmtB 被选为模型，以深入了解高温下的这种分子机制。在本研究中，采用多学科方法，对该蛋白进行了结构和功能表征，重点研究了其金属相互作用和理化稳定性。我们的数据表明，TtSmtB 每个单体具有两个不同的金属结合位点，并与二价、三价和五价离子以不同的亲和力相互作用。在分子水平上详细了解蛋白质-金属相互作用对于设计基于金属的治疗、金属生物回收或环境中的金属生物传感中的金属结合结构域作为支架是非常重要的。
