Eide David J
Department of Nutritional Sciences, University of Wisconsin-Madison, 1415 Linden Drive, Madison, WI, 53706, USA.
Mol Microbiol. 2014 Nov;94(4):743-6. doi: 10.1111/mmi.12793. Epub 2014 Sep 30.
Zinc is a catalytic or structural cofactor of numerous proteins but can also be toxic if cells accumulate too much of this essential metal. Therefore, mechanisms of zinc homeostasis are needed to maintain a low but adequate amount of free zinc so that newly translated zinc-dependent proteins can bind their cofactor without confounding issues of toxicity. These mechanisms include the regulation of uptake and efflux transporters and buffering of the free metal concentration by low-molecular-weight ligands in the cytosol. While many of the transporters involved in zinc homeostasis have been discovered in recent years, the molecules that buffer zinc have remained largely a mystery. In the new report highlighted by this commentary, Ma et al. (2014) provide convincing evidence that bacillithiol, the major low-molecular-weight thiol compound in Bacillus subtilis, serves as an important zinc buffer in those cells. Their discovery provides an important piece to the puzzle of how zinc buffering occurs in a large number of microbes and provides new clues about the role and relative importance of zinc buffering in all organisms.
锌是众多蛋白质的催化或结构辅助因子，但如果细胞积累了过多这种必需金属，它也可能具有毒性。因此，需要锌稳态机制来维持低水平但适量的游离锌，以便新翻译的锌依赖性蛋白质能够结合其辅助因子，而不会出现毒性混淆问题。这些机制包括调节摄取和外流转运蛋白，以及通过细胞质中的低分子量配体缓冲游离金属浓度。虽然近年来已经发现了许多参与锌稳态的转运蛋白，但缓冲锌的分子在很大程度上仍然是个谜。在本评论所强调的新报告中，Ma等人（2014年）提供了令人信服的证据，表明枯草芽孢杆菌中的主要低分子量硫醇化合物杆菌硫醇在这些细胞中充当重要的锌缓冲剂。他们的发现为大量微生物中锌缓冲如何发生这一谜题提供了重要的一块，并为锌缓冲在所有生物体中的作用和相对重要性提供了新线索。
