Douglas S E, Durnford D G
Atlantic Research Laboratory, National Research Council, Halifax, Nova Scotia, Canada.
Plant Mol Biol. 1989 Jul;13(1):13-20. doi: 10.1007/BF00027331.
The gene for the small subunit of ribulose-1,5-bisphosphate carboxylase (Rubisco) is located in the large single-copy region of the plastid genome of the chlorophyll c-containing alga Cryptomonas phi. The coding sequence is 417 base pairs long, encoding a protein of 139 amino acids, considerably longer than most other small subunit proteins. It is found 83 base pairs downstream from the gene for the large subunit and is cotranscribed with it. An 18 base pair perfect inverted repeat is located 8 base pairs beyond the termination codon. Sequence analysis shows the gene to be more closely related to cyanobacterial and cyanelle small-subunit genes than to those of green algae or land plants. This is the first reported sequence of a Rubisco small-subunit gene which is plastid-encoded and it exhibits a number of unique features. The derived amino acid sequence shows extensive similarity to a partial amino acid sequence from a brown alga, indicating that this gene will be of major interest as a probe for the small subunit genes in other algae and for determining possible evolutionary ancestors of algal plastids.
1,5-二磷酸核酮糖羧化酶（Rubisco）小亚基的基因位于含有叶绿素c的藻类隐球藻质体基因组的大单拷贝区域。编码序列长417个碱基对，编码一个139个氨基酸的蛋白质，比大多数其他小亚基蛋白长得多。它位于大亚基基因下游83个碱基对处，并与之共转录。一个18个碱基对的完美反向重复序列位于终止密码子下游8个碱基对处。序列分析表明，该基因与蓝细菌和蓝藻小亚基基因的关系比与绿藻或陆生植物的关系更密切。这是首次报道的质体编码的Rubisco小亚基基因序列，它具有许多独特的特征。推导的氨基酸序列与一种褐藻的部分氨基酸序列具有广泛的相似性，这表明该基因作为其他藻类小亚基基因的探针以及确定藻类质体可能的进化祖先将具有重要意义。
