School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia 5005, Australia.
Arch Biochem Biophys. 2010 Apr 1;496(1):45-52. doi: 10.1016/j.abb.2010.01.015. Epub 2010 Feb 11.
Holocarboxylase synthetase (HCS) governs the cellular fate of the essential micronutrient biotin (Vitamin H or B7). HCS is responsible for attaching biotin onto the biotin-dependent enzymes that reside in the cytoplasm and mitochondria. Evidence for an alternative role, viz the regulation of gene expression, has also been reported. Recent immunohistochemical studies reported HCS is primarily nuclear, inconsistent with the location of HCS activity. Improved understanding of biotin biology demands greater knowledge about HCS. Here, we investigated the localisation of HCS and its isoforms. Three variants were observed that differ at the N-terminus. All HCS isoforms were predominantly non-nuclear, consistent with the distribution of biotin protein ligase activity. Unlike the longer constructs, the Met(58) isoform was also detected in the nucleus--a novel observation suggesting shuttling activity between nucleus and cytoplasm. We resolved that the previous controversies in the literature are due to specificity and detection limitations that arise when using partially purified antibodies.
羟羧基酶（HCS）决定了生物素（维生素 H 或 B7）这一必需微量营养素的细胞命运。HCS 负责将生物素附着在细胞质和线粒体中存在的生物素依赖性酶上。也有报道称其具有调节基因表达的替代作用。最近的免疫组织化学研究报告称，HCS 主要存在于核内，与 HCS 活性的位置不一致。为了更好地了解生物素生物学，需要更多关于 HCS 的知识。在这里，我们研究了 HCS 及其同工型的定位。观察到三种在 N 端存在差异的变体。所有 HCS 同工型主要是非核的，与生物素蛋白连接酶活性的分布一致。与较长的构建体不同，Met(58)同工型也在核内被检测到——这是一个新的观察结果，表明核质之间存在穿梭活性。我们解决了文献中以前的争议，这些争议是由于使用部分纯化的抗体时出现的特异性和检测限制。
