Matthiadis Anna, Long Terri A
a Department of Plant and Microbial Biology , North Carolina State University , Raleigh , NC , USA.
Plant Signal Behav. 2016 Aug 2;11(8):e1204508. doi: 10.1080/15592324.2016.1204508.
BRUTUS (BTS) is a hemerythrin (HHE) domain containing E3 ligase that facilitates the degradation of POPEYE-like (PYEL) proteins in a proteasomal-dependent manner. Deletion of BTS HHE domains enhances BTS stability in the presence of iron and also complements loss of BTS function, suggesting that the HHE domains are critical for protein stability but not for enzymatic function. The RING E3 domain plays an essential role in BTS' capacity to both interact with PYEL proteins and to act as an E3 ligase. Here we show that removal of the RING domain does not complement loss of BTS function. We conclude that enzymatic activity of BTS via the RING domain is essential for response to iron deficiency in plants. Further, we analyze possible BTS domain structure evolution and predict that the combination of domains found in BTS is specific to photosynthetic organisms, potentially indicative of a role for BTS and its orthologs in mitigating the iron-related challenges presented by photosynthesis.
BRUTUS（BTS）是一种含有血青素（HHE）结构域的E3连接酶，它以蛋白酶体依赖的方式促进类大力水手（PYEL）蛋白的降解。在铁存在的情况下，删除BTS的HHE结构域可增强BTS的稳定性，并且还能弥补BTS功能的丧失，这表明HHE结构域对蛋白质稳定性至关重要，但对酶功能并非如此。RING E3结构域在BTS与PYEL蛋白相互作用以及作为E3连接酶的能力中起着至关重要的作用。在此我们表明，去除RING结构域并不能弥补BTS功能的丧失。我们得出结论，BTS通过RING结构域的酶活性对于植物对缺铁的反应至关重要。此外，我们分析了BTS结构域可能的进化，并预测BTS中发现的结构域组合是光合生物特有的，这可能表明BTS及其直系同源物在应对光合作用带来的与铁相关的挑战中发挥作用。
