Division of Biochemistry, Interdisciplinary Plant Group, and Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211, USA.
J Biol Chem. 2011 Mar 4;286(9):7548-57. doi: 10.1074/jbc.M110.182865. Epub 2010 Dec 28.
Sulfurtransferases (STRs) catalyze the transfer of a sulfur atom from a donor to a suitable acceptor molecule. The Arabidopsis thaliana genome encodes 20 putative STR proteins. The biological functions of most are unclear. We found that STR1 and STR2 play important roles in embryo/seed development. Mutation of STR1 alone resulted in a shrunken seed phenotype, although growth and development of vegetative and reproductive organs were not affected. The shrunken seed phenotype was associated with the delayed/arrested embryo development, in most cases, at the heart stage. The embryo defect of str1 mutant is not fully penetrant. Approximately 12.5% of embryos developed further and formed normal looking seeds. In severely shrunken seeds, no embryo could be identified after seed collection. Partially shrunken seeds that contained viable embryos could still germinate. However, cotyledons of the seedlings from such seeds were abnormal. An STR1-GUS fusion reporter revealed that the STR1 gene was universally expressed, with high levels of expression in specific tissues/organs including embryos. The incomplete penetrance of str1 embryo/seed phenotype is a result of functional STR2. Single str2 mutant had no phenotype. However, no str1(-/-)/str2(-/-) double mutant embryos were able to develop past the heart stage. Furthermore, STR2 is haplo-insufficient in str1 mutant background, and str1(-/-)/str2(+/-) embryos were 100% lethal. These data provide new insights into the biological functions of the ubiquitous sulfurtransferase in Arabidopsis embryogenesis and seed development.
硫转移酶（STRs）催化硫原子从供体向合适的受体分子转移。拟南芥基因组编码 20 种假定的 STR 蛋白。大多数的生物学功能尚不清楚。我们发现 STR1 和 STR2 在胚胎/种子发育中起重要作用。单独突变 STR1 导致种子变小的表型，尽管营养和生殖器官的生长和发育不受影响。种子变小的表型与胚胎发育延迟/停滞有关，在大多数情况下，处于心脏期。str1 突变体的胚胎缺陷不是完全显性的。大约 12.5%的胚胎进一步发育并形成正常的种子。在严重变小的种子中，种子收集后无法识别胚胎。部分变小的种子中仍含有存活的胚胎仍能发芽。然而，来自这些种子的幼苗子叶是异常的。STR1-GUS 融合报告基因揭示 STR1 基因普遍表达，在包括胚胎在内的特定组织/器官中表达水平较高。str1 胚胎/种子表型不完全显性是 STR2 功能的结果。str2 单突变体没有表型。然而，str1(-/-)/str2(-/-)双突变体胚胎无法发育到心脏期之后。此外，STR2 在 str1 突变体背景下是杂合不足的，str1(-/-)/str2(+/-)胚胎是 100%致死的。这些数据为广泛存在的硫转移酶在拟南芥胚胎发生和种子发育中的生物学功能提供了新的见解。
