Wang S L, Liu X Q
Canadian Institute for Advanced Research, Department of Biochemistry, Dalhousie University, Halifax, NS.
Proc Natl Acad Sci U S A. 1991 Dec 1;88(23):10783-7. doi: 10.1073/pnas.88.23.10783.
The plastid genome of Cryptomonas phi, a cryptomonad alga, contains three genes that have not previously been found in any organellar genome. Each of these genes encodes a functional class of organellar gene product not previously reported. The first gene, dnaK, encodes a polypeptide of the hsp70 heat shock protein family. The predicted amino acid sequence of the DnaK protein is 54% identical to that of the Escherichia coli hsp70 protein (DnaK), 50-53% identical to that of two nucleus-encoded mitochondrial hsp70 proteins, and 43-46% identical to that of several eukaryotic cytoplasmic members of the hsp70 protein family. The second gene, hlpA, encodes a polypeptide resembling bacterial histone-like proteins. The predicted amino acid sequence of the HlpA protein is 25-53% identical to that of several bacterial histone-like proteins, and the identity increases to 39-76% over a conserved region corresponding to the long arm that binds DNA. The third gene, acpA, encodes an acyl carrier protein, which is a key cofactor in the synthesis and metabolism of fatty acids. Its predicted amino acid sequence is 36-59% identical to that of eubacterial and plant chloroplast (nucleus-encoded) acyl carrier proteins.
隐藻门藻类隐甲藻（Cryptomonas phi）的质体基因组包含三个此前在任何细胞器基因组中均未发现的基因。这些基因中的每一个都编码一类此前未报道过的细胞器基因产物。第一个基因dnaK编码hsp70热休克蛋白家族的一种多肽。预测的DnaK蛋白氨基酸序列与大肠杆菌hsp70蛋白（DnaK）的序列有54%的同一性，与两种细胞核编码的线粒体hsp70蛋白的序列有50 - 53%的同一性，与hsp70蛋白家族的几种真核细胞质成员的序列有43 - 46%的同一性。第二个基因hlpA编码一种类似于细菌类组蛋白的多肽。预测的HlpA蛋白氨基酸序列与几种细菌类组蛋白的序列有25 - 53%的同一性，在对应于结合DNA的长臂的保守区域，同一性增加到39 - 76%。第三个基因acpA编码一种酰基载体蛋白，它是脂肪酸合成和代谢中的关键辅助因子。其预测的氨基酸序列与真细菌和植物叶绿体（细胞核编码）酰基载体蛋白的序列有36 - 59%的同一性。
