Bhalerao R P, Lind L K, Persson C E, Gustafsson P
Department of Plant Physiology, Umeå University, Sweden.
Mol Gen Genet. 1993 Feb;237(1-2):89-96. doi: 10.1007/BF00282788.
The phycobilisome rod linker genes in the two closely related cyanobacteria Synechococcus sp. PCC 6301 and Synechococcus sp. PCC 7942 were studied. Southern blot analysis showed that the genetic organization of the phycobilisome rod operon is very similar in the two strains. The phycocyanin gene pair is duplicated and separated by a region of about 2.5 kb. The intervening region between the duplicated phycocyanin gene pair was cloned from Synechococcus sp. PCC 6301 and sequenced. Analysis of this DNA sequence revealed the presence of three open reading frames corresponding to 273, 289 and 81 amino acids, respectively. Insertion of a kanamycin resistance cassette into these open reading frames indicated that they corresponded to the genes encoding the 30, 33 and 9 kDa rod linkers, respectively, as judged by the loss of specific linkers from the phycobilisomes of the insertional mutants. Amino acid compositions of the 30 and 33 kDa linkers derived from the DNA sequence were found to deviate from those of purified 33 and 30 kDa linkers in the amounts of glutamic acid/glutamine residues. On the basis of similarity of the amino acid sequence of the rod linkers between Synechococcus sp. PCC 6301 and Calothrix sp. PCC 7601 we name the genes encoding the 30, 33 and 9 kDa linkers cpcH, cpcI and cpcD, respectively. The three linker genes were found to be co-transcribed on an mRNA of 3700 nucleotides. However, we also detected a smaller species of mRNA, of 3400 nucleotides, which would encode only the cpcH and cpcI genes.(ABSTRACT TRUNCATED AT 250 WORDS)
对两种亲缘关系密切的蓝细菌聚球藻属（Synechococcus）的PCC 6301菌株和聚球藻属的PCC 7942菌株中的藻胆体杆状连接蛋白基因进行了研究。Southern印迹分析表明，这两种菌株中藻胆体杆状操纵子的基因组织非常相似。藻蓝蛋白基因对被复制，并被一个约2.5 kb的区域隔开。从聚球藻属的PCC 6301菌株中克隆出重复的藻蓝蛋白基因对之间的间隔区域并进行测序。对该DNA序列的分析揭示了分别对应于273、289和81个氨基酸的三个开放阅读框的存在。将卡那霉素抗性盒插入这些开放阅读框表明，它们分别对应于编码30 kDa、33 kDa和9 kDa杆状连接蛋白的基因，这是通过插入突变体的藻胆体中特定连接蛋白的缺失来判断的。从DNA序列推导的30 kDa和33 kDa连接蛋白的氨基酸组成在谷氨酸/谷氨酰胺残基的数量上与纯化的33 kDa和30 kDa连接蛋白不同。基于聚球藻属的PCC 6301菌株和眉藻属的PCC 7601菌株之间杆状连接蛋白氨基酸序列的相似性，我们分别将编码30 kDa、33 kDa和9 kDa连接蛋白的基因命名为cpcH、cpcI和cpcD。发现这三个连接蛋白基因在一个3700个核苷酸的mRNA上共转录。然而，我们也检测到一种较小种类的mRNA，其长度为3400个核苷酸，它仅编码cpcH和cpcI基因。（摘要截短至250字）
