The United Graduate School of Agricultural Science, Gifu University, Gifu, Japan.
The Graduate School of Natural Sciences and Technologies, Gifu University, Gifu, Japan.
Enzyme Microb Technol. 2020 May;136:109518. doi: 10.1016/j.enzmictec.2020.109518. Epub 2020 Jan 30.
XoxF-type methanol dehydrogenase was recently found to be lanthanide-dependent, while its counterpart MxaF is Ca-dependent. The lanthanide (Ln) series consists of 15 different elements, all of which exist in nature, although at different relative abundances. XoxF from Methylorubrum extorquens strain AM1 has been shown to be induced by four light Ln species (La to Nd). The preference of XoxFs for certain co-existing Ln species and the catalytic activity and stability of XoxF metallated with different Ln species have not been well investigated. In this study, we found that (i) strain AM1 cells preferentially utilize La rather than Nd for growth, (ii) XoxF purified from cells grown with a La and Nd mixture contained a larger proportion of La, and (iii) La-metallated XoxF has higher activity and thermal stability than Nd-metallated XoxF, although (iv) both enzymes showed unchanged surface charges. Thermal shift assay in particular revealed that metallation affects the temperature for subunit denaturation but not for subunit dissociation. We concluded that, although La and Nd have similar distributions in nature, XoxF could chose La preferentially.
XoxF 型甲醇脱氢酶最近被发现依赖于镧系元素，而其对应的 MxaF 则依赖于 Ca。镧系元素（Ln）系列由 15 种不同的元素组成，它们都存在于自然界中，尽管相对丰度不同。从甲基杆菌菌株 AM1 中分离出的 XoxF 已被证明可被四种轻镧系元素（La 到 Nd）诱导。XoxF 对某些共存的镧系元素的偏好以及用不同的镧系元素金属化的 XoxF 的催化活性和稳定性尚未得到很好的研究。在这项研究中，我们发现：（i）细胞优先利用 La 而不是 Nd 进行生长；（ii）从用 La 和 Nd 混合物培养的细胞中纯化的 XoxF 含有更大比例的 La；（iii）La 金属化的 XoxF 比 Nd 金属化的 XoxF 具有更高的活性和热稳定性，尽管（iv）两种酶的表面电荷都没有变化。特别是热位移测定表明，金属化影响亚基变性的温度，而不影响亚基解离的温度。我们得出结论，尽管 La 和 Nd 在自然界中的分布相似，但 XoxF 可以优先选择 La。
