Division of Biotechnology, College of Environmental & Bioresources Sciences, Jeonbuk National University, Iksan 54596, Korea.
Department of Herbal Medicine Resources, College of Environmental and Bioresource Sciences, Jeonbuk National University, Iksan 54596, Korea.
Mol Cells. 2020 Sep 30;43(9):784-792. doi: 10.14348/molcells.2020.0136.
Arginine kinase (AK), a bioenergy-related enzyme, is distributed widely in invertebrates. The role of highly conserved histidines in AKs is still unascertained. In this study, the highly conserved histidine 284 (H284) in AK of (AK) was replaced with alanine to elucidate the role of H284. We examined the alteration of catalytic activity and structural changes of H284A in AK. The catalytic activity of H284A was reduced dramatically compared to that in wild type (WT). Thus the crystal structure of H284A displayed several structural changes, including the alteration of D324, a hydrogen-bonding network around H284, and the disruption of π-stacking between the imidazole group of the H284 residue and the adenine ring of ATP. These findings suggest that such alterations might affect a conformational change of the specific loop consisting of G310-V322 at the antiparallel β-sheet region. Thus, we speculated that the H284 residue might play an important role in the conformational change of the specific loop when ATP binds to the substrate-binding site of AK.
精氨酸激酶（AK）是一种与生物能量相关的酶，广泛分布于无脊椎动物中。高度保守的组氨酸在 AK 中的作用仍未确定。在这项研究中，我们用丙氨酸替换了 AK 中的高度保守的组氨酸 284（H284），以阐明 H284 的作用。我们研究了 H284A 在 AK 中的催化活性和结构变化。与野生型（WT）相比，H284A 的催化活性显著降低。因此，H284A 的晶体结构显示出一些结构变化，包括 D324 的改变、围绕 H284 的氢键网络以及 H284 残基的咪唑基团与 ATP 的腺嘌呤环之间的π-堆积的破坏。这些发现表明，这些变化可能会影响由 G310-V322 组成的特定环的构象变化，该环位于反平行β-折叠区域。因此，我们推测当 ATP 结合到 AK 的底物结合位点时，H284 残基可能在特定环的构象变化中发挥重要作用。
