Orme W, Walker A R, Gupta R, Gray J C
Department of Plant Sciences and Cambridge Centre for Molecular Recognition, University of Cambridge, UK.
Plant Mol Biol. 2001 Jul;46(5):615-26. doi: 10.1023/a:1010665702621.
Arabidopsis cDNAs encoding ATJ11, the smallest known J-domain protein, have been isolated and characterized. The precursor protein of 161 amino acid residues was synthesized in vitro and imported by isolated pea chloroplasts where it was localized to the stroma and cleaved to a mature protein of 125 amino acid residues. The mature protein consists of an 80 amino acid J-domain, and N- and C-terminal extensions of 24 and 21 amino acid residues, respectively, which show no similarity to regions in other DnaJ-related proteins. ATJ11 produced in Escherichia coli stimulated the weak ATPase activity of E. coli DnaK, but was unable to stimulate refolding of firefly luciferase by DnaK, and inhibited refolding by DnaK, DnaJ and GrpE. ATJ11 is encoded by a single-copy gene on chromosome 4, and is expressed in all plant organs examined. A paralogue of ATJ11, showing 72% identity, is encoded in a 4.5 Mb duplication of chromosome 4 on chromosome 2. These proteins represent a novel class of J-domain proteins.
已分离并鉴定出编码已知最小的J结构域蛋白ATJ11的拟南芥cDNA。由161个氨基酸残基组成的前体蛋白在体外合成，并被分离的豌豆叶绿体导入，在叶绿体中它定位于基质并被切割成由125个氨基酸残基组成的成熟蛋白。成熟蛋白由一个80个氨基酸的J结构域以及分别为24个和21个氨基酸残基的N端和C端延伸组成，这与其他DnaJ相关蛋白的区域没有相似性。在大肠杆菌中产生的ATJ11刺激了大肠杆菌DnaK的微弱ATP酶活性，但无法刺激DnaK对萤火虫荧光素酶的重折叠，并且抑制了DnaK、DnaJ和GrpE的重折叠。ATJ11由位于4号染色体上的单拷贝基因编码，并在所检测的所有植物器官中表达。在2号染色体上4号染色体4.5 Mb的重复片段中编码了与ATJ11具有72%同一性的一个旁系同源物。这些蛋白代表了一类新型的J结构域蛋白。
