摘要
在紫云英根瘤菌(Rhizobium astragali)的基因组中存在有DNA重复顺序(RSRa)。它在Ra159的基因组中重复4～5次,其中一个拷贝位于nifH基因的上游。以1.25kbPvul片段作探针,在其他紫云英根瘤菌菌株及豌豆根瘤菌RI PRE中也都检测到与RSRa同源的DNA片段。序列测定的结果表明RSRa其结构类似于IS因子,具有原核插入顺序的一些特点。RSRa全长1468bp,在RSRa的两个末端具有反向重复顺序,RSRa中有一个大的开放阅读框架(ORF)。由ORF推定的蛋白与大肠杆菌插入顺序IS903推定的转座酶有较高的同源性。
A DNA repeated sequence has been found in the Rhizobium astragali genome designated as RSRa. It is repeated 4 - 5 times in the genome. One copy of it is located upstream of nifH. By using of a 1.25kb Pvul fragment as a specific probe, homologous RSRa was detected in different strains of R. astragali and also in one strain of R. leguminosarum PRE tested. Nucleotide sequence analysis revealed that RSRa possesses the structural characteristics of prokaryotic insertion sequence elements. RSRa is 1468 bp in length with 398 bp terminal inverted repeats. A large open reading frame, putatively the gene coding for transponase, was found in the RSRa. Comparison of the putative protein encoded with sequences derived from the GeneBank and SWISS-Prot datebase showed significant similarity between the putative transponase encoded by RSRa and that encoded by E. coli IS903.
出处
《微生物学报》
CAS
CSCD
北大核心
1997年第3期171-178,共8页
Acta Microbiologica Sinica
