Structure and function of plastid nucleoid

类叶绿体是原核生物DNA与真核DNA结合蛋白的复合体或杂交体，是叶绿体DNA的功能单位。基于这一观点，我们试图鉴定叶绿体类核的成分，并分析它们在叶绿体DNA复制和转录中的功能。拟南芥基因组全序列的公布使我们得出结论：许多原核类核蛋白在高等植物中并不存在。例如HU蛋白和DPS蛋白，它们普遍存在于原核生物中，但在拟南芥的叶绿体中不存在。许多类核蛋白肯定是在陆地植物进化过程中通过复制或修饰编码真核DNA结合蛋白的核基因而获得的。这些结果促使我们提出了关于叶绿体基因组机制不连续进化的假说。

Plastid nucleoid, which is a functional unit of plastid DNA, is considered as a complex or hybrid of prokaryotic DNA with eukaryotic DNA-binding proteins. Based on this standpoint, we tried to identify the components of plastid nucleoids and to analyze their function in the replication and transcription of plastid DNA. The publication of the complete nucleotide sequence of the genome of Arabidopsis thaliana made us conclude that many of the prokaryotic nucleoid proteins are not present in higher plants. Examples are the HU protein and Dps protein that are ubiquitously present in prokaryotes but these are not present in the chloroplast of A. thaliana.Many of the nucleoid proteins must have been acquired during the evolution of land plants by duplication or modification of the nuclear genes encoding eukaryotic DNA-binding proteins. These results prompted us to put forward a hypothesis on the discontinuous evolution of plastid genomic machinery.