Erent M, Gonin P, Cherfils J, Tissier P, Raschellà G, Giartosio A, Agou F, Sarger C, Lacombe M L, Konrad M, Lascu I
Institut de Biochimie et Génétique Cellulaires (UMR 5095), Centre National de la Recherche Scientifique et Université de Bordeaux-2, France.
Eur J Biochem. 2001 Apr;268(7):1972-81. doi: 10.1046/j.1432-1327.2001.2076.doc.x.
The human DRnm23 gene was identified by differential screening of a cDNA library obtained from chronic myeloid leukaemia-blast crisis primary cells. The over-expression of this gene inhibits differentiation and induces the apoptosis of myeloid precursor cell lines. We overproduced in bacteria a truncated form of the encoded protein lacking the first 17 N-terminal amino acids. This truncated protein was called nucleoside diphosphate (NDP) kinase CDelta. NDP kinase CDelta had similar kinetic properties to the major human NDP kinases A and B, but was significantly more stable to denaturation by urea and heat. Analysis of denaturation by urea, using size exclusion chromatography, indicated unfolding without the dissociation of subunits, whereas renaturation occurred via a folded monomer. The stability of the protein depended primarily on subunit interactions. Homology modelling of the structure of NDP kinase CDelta, based on the crystal structure of NDP kinase B, indicated that NDP kinase CDelta had several additional stabilizing interactions. The overall structure of the two enzymes appears to be identical because NDP kinase CDelta readily formed mixed hexamers with NDP kinase A. It is possible that mixed hexamers can be observed in vivo.
人类DRnm23基因是通过对从慢性髓性白血病急变期原代细胞获得的cDNA文库进行差异筛选而鉴定出来的。该基因的过表达会抑制分化并诱导髓系前体细胞系凋亡。我们在细菌中过量表达了编码蛋白的截短形式，该截短形式缺少前17个N端氨基酸。这种截短蛋白被称为核苷二磷酸（NDP）激酶CDelta。NDP激酶CDelta具有与主要的人类NDP激酶A和B相似的动力学特性，但对尿素和热变性的稳定性明显更高。使用尺寸排阻色谱法对尿素变性进行分析表明，其解折叠过程中没有亚基解离，而复性是通过折叠的单体进行的。该蛋白的稳定性主要取决于亚基相互作用。基于NDP激酶B的晶体结构对NDP激酶CDelta的结构进行同源建模表明，NDP激酶CDelta具有几种额外的稳定相互作用。这两种酶的整体结构似乎是相同的，因为NDP激酶CDelta很容易与NDP激酶A形成混合六聚体。在体内有可能观察到混合六聚体。
