National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Chongqing Normal University, Chongqing, 401331, China.
Plant Cell Rep. 2019 Mar;38(3):321-331. doi: 10.1007/s00299-018-2368-4. Epub 2019 Jan 2.
FLA, the homolog of ubiquitin-specific protease does not have deubiquitination activity, but it is essential for flower and chloroplast development in rice. Ubiquitin-specific proteases (UBPs) are widely distributed and highly conserved proteins and are also members of the most important family of deubiquitination enzymes. Although the functions and phylogenies of UBPs from yeast, mammals and Arabidopsis have been widely reported, the functions and evolutionary relationships of UBPs in rice remain unclear. In this study, we characterized the rice flower and leaf color aberrant mutant (fla), which exhibited a variety of developmental defects, including abnormal floral organs and pollen development, and leaf bleaching. We isolated FLA by positional cloning and found that it encodes a homolog of ubiquitin-specific protease. FLA is a ubiquitously expressed gene with the highest expression in floral organs. Subcellular localization analysis indicated that FLA is a cell membrane protein. Through searches of the rice genome database ( http://rice.plantbiology.msu.edu ), we identified 35 UBP family members in the rice genome. These proteins were grouped into 16 subfamilies based on phylogenetic analysis, and FLA was found to belong to the G8 subfamily. In vitro activity assays revealed that FLA does not have deubiquitination activity. Our data suggest that FLA plays an important role in the development of floral organs and chloroplast in rice, but that this role probably does not involve deubiquitination activity, because FLA does not have an active site and deubiquitination activity.
FLA，泛素特异性蛋白酶的同源物没有去泛素化活性，但它对水稻的花和叶绿体发育是必不可少的。泛素特异性蛋白酶（UBPs）广泛分布且高度保守，也是去泛素化酶最重要家族的成员。尽管酵母、哺乳动物和拟南芥的 UBP 的功能和系统发育已经得到广泛报道，但水稻 UBP 的功能和进化关系仍不清楚。在这项研究中，我们对表现出多种发育缺陷的水稻花和叶色异常突变体（fla）进行了表征，包括异常的花器官和花粉发育以及叶片白化。我们通过定位克隆分离了 FLA，发现它编码泛素特异性蛋白酶的同源物。FLA 是一种广泛表达的基因，在花器官中表达量最高。亚细胞定位分析表明 FLA 是一种质膜蛋白。通过对水稻基因组数据库（http://rice.plantbiology.msu.edu）的搜索，我们在水稻基因组中鉴定出 35 个 UBP 家族成员。这些蛋白质根据系统发育分析分为 16 个亚家族，FLA 被发现属于 G8 亚家族。体外活性测定表明 FLA 没有去泛素化活性。我们的数据表明，FLA 在水稻花器官和叶绿体的发育中发挥重要作用，但这种作用可能不涉及去泛素化活性，因为 FLA 没有活性位点和去泛素化活性。
