Requena J M, López M C, Jimenez-Ruiz A, de la Torre J C, Alonso C
Centro de Biología Molecular, Universidad Autónoma de Madrid, Spain.
Nucleic Acids Res. 1988 Feb 25;16(4):1393-406. doi: 10.1093/nar/16.4.1393.
We describe the isolation and characterization of the T. cruzi hsp 70 DNA coding region which was found to be formed by multigene copies organized in a tandem array in a head-to-tail manner. The restriction pattern of one of the repetition units within the largest clone obtained from the genomic library, clone Tc70.6, shows that the hsp70 coding region should be formed by at least seven identical copies of 2.5 kb. We have found, however, the presence of restriction polymorphisms (Pvu II) within these repeats. Subsequent analysis of the time course of nuclear DNA digestion has revealed that the copy number per haploid genome could be as greater as 10. The analysis of the DNA and amino acid sequence of a fragment (70%) of one of the repetition units has shown the existence of a high homology with all the hsp70 genes of other organisms. The protein sequence homology of the fragment analyzed is as high as 88% when compared with that of the T. brucei hsp70. On the other hand, there are significant restriction site variations between both. The T. cruzi hsp70 contains at the C-terminal end a tetrapeptide repeat of the structure (GMPG)9.
我们描述了克氏锥虫热休克蛋白70（hsp 70）DNA编码区的分离和特性，发现其由多基因拷贝组成，这些拷贝以头对尾的方式串联排列。从基因组文库中获得的最大克隆之一，即克隆Tc70.6，其中一个重复单元的限制性图谱显示，hsp70编码区应由至少七个2.5 kb的相同拷贝组成。然而，我们发现这些重复序列中存在限制性多态性（Pvu II）。随后对核DNA消化时间进程的分析表明，单倍体基因组中的拷贝数可能高达10个。对其中一个重复单元的一个片段（70%）的DNA和氨基酸序列分析表明，它与其他生物的所有hsp70基因存在高度同源性。与布氏锥虫hsp70相比，所分析片段的蛋白质序列同源性高达88%。另一方面，两者之间存在显著的限制性位点差异。克氏锥虫hsp70在C末端含有结构为（GMPG）9的四肽重复序列。
