Centre for Plant Molecular Biology, Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montreal, Canada H3A 1B1.
Proc Natl Acad Sci U S A. 1985 Aug;82(15):5040-4. doi: 10.1073/pnas.82.15.5040.
Nodulin-35 (N-35), a subunit of nodule-specific uricase (uricase II) of soybean (Glycine max), is shown to be preferentially synthesized on free polysomes during nodule development and is localized in peroxisomes of the uninfected cells of this tissue. A cDNA clone, isolated by using mRNA from immunoprecipitated polysomes, revealed the primary structure of this protein with a molecular mass of 35,100. That this clone represents N-35 was confirmed by comparing the deduced amino acid sequence with the partial sequence of a CNBr-cleaved peptide of purified N-35. Southern blot hybridizations with genomic DNA suggest that there are several EcoRI fragments containing N-35 sequences. Three of these sequences were isolated from a genomic library of soybean. Nucleotide sequence analysis showed that the complete gene extends almost 5000 base pairs on two EcoRI fragments and the coding region (309 codons) is interrupted by seven introns ranging in size from 154 to 1341 base pairs. Lack of a signal sequence and its translation on free polysomes suggest that N-35 is posttranslationally transported to the peroxisomes. Furthermore, there is no cross-hybridization of N-35 cDNA with RNA from young (3- to 4-day) roots and leaves, indicating that the observed "uricase" activity in these tissues is due to the product of a different gene.
豆球蛋白 35（N-35）是大豆（Glycine max）结瘤特异性尿酸酶（尿酸酶 II）的亚基，研究表明它在结瘤过程中优先在游离多核糖体上合成，并定位于该组织未感染细胞的过氧化物酶体中。利用免疫沉淀多核糖体中的 mRNA 分离出的 cDNA 克隆，揭示了该蛋白的一级结构，其分子量为 35100。通过将推导的氨基酸序列与纯化的 N-35 的 CNBr 切割肽的部分序列进行比较，证实了该克隆代表 N-35。用基因组 DNA 进行 Southern blot 杂交表明，存在几个包含 N-35 序列的 EcoRI 片段。其中三个序列从大豆的基因组文库中分离出来。核苷酸序列分析表明，完整基因在两个 EcoRI 片段上延伸近 5000 个碱基对，编码区（309 个密码子）被大小为 154 到 1341 个碱基对的七个内含子打断。缺乏信号序列及其在游离多核糖体上的翻译表明，N-35 是在翻译后被运送到过氧化物酶体的。此外，N-35 cDNA 与来自年轻（3-4 天）根和叶的 RNA 之间没有交叉杂交，这表明在这些组织中观察到的“尿酸酶”活性是由于不同基因的产物所致。
