Kavanagh T A, Jefferson R A, Bevan M W
Department of Molecular Genetics, Institute of Plant Science Research, Cambridge Laboratory, Trumpington, UK.
Mol Gen Genet. 1988 Dec;215(1):38-45. doi: 10.1007/BF00331300.
We have constructed chimaeric genes consisting of sequences encoding the transit peptide and 4, 16, 24, 53 or 126 amino-terminal residues of the mature chlorophyll a/b binding (Cab) apoprotein fused to the Escherichia coli gene encoding beta-glucuronidase (GUS). These genes were introduced into tobacco plants and the fate of the fusion proteins they encode was analysed. Less than 1% of the total activity of fusion proteins containing the transit peptide and 4 (FP4) or 16 (FP16) amino-terminal amino acids of the mature Cab protein was associated with chloroplasts. Moreover, FP4 appears to be unprocessed. This is in striking contrast to fusion proteins containing the transit peptide and 24 (FP24), 53 (FP53) or 126 (FP126) amino-terminal residues of the mature Cab polypeptide. Approximately 98%, 96% or 75%, respectively, of the total activity of these fusion proteins was associated with purified intact chloroplasts, and protease protection experiments showed that of this, approximately 98%, 87% or 50%, respectively, was located within this organelle. Furthermore, both FP24 and FP53 appear to be processed. However, less than 10% of the activity of those fusion proteins translocated into chloroplasts was associated with thylakoid membranes.
我们构建了嵌合基因，其由编码转运肽以及成熟叶绿素a/b结合（Cab）脱辅基蛋白的4、16、24、53或126个氨基末端残基的序列组成，并与编码β-葡萄糖醛酸酶（GUS）的大肠杆菌基因融合。将这些基因导入烟草植株，并分析它们所编码的融合蛋白的命运。含有转运肽以及成熟Cab蛋白4个（FP4）或16个（FP16）氨基末端氨基酸的融合蛋白，其总活性中不到1%与叶绿体相关。此外，FP4似乎未被加工。这与含有转运肽以及成熟Cab多肽24个（FP24）、53个（FP53）或126个（FP126）氨基末端残基的融合蛋白形成了鲜明对比。这些融合蛋白的总活性分别约有98%、96%或75%与纯化的完整叶绿体相关，蛋白酶保护实验表明，其中分别约有98%、87%或50%位于该细胞器内。此外，FP24和FP53似乎都经过了加工。然而，转运到叶绿体中的那些融合蛋白的活性中，只有不到10%与类囊体膜相关。
