Baker K P, Baron W F, Henzel W J, Spencer S A
Department of Molecular Biology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
Gene. 1998 Jul 30;215(2):281-9. doi: 10.1016/s0378-1119(98)00280-7.
We have cloned and sequenced novel cDNAs that encode human and murine DNase II, the acidic deoxyribonuclease. Sequence analysis predicts that huDNase II contains an N-terminal signal sequence and that mature DNase II has 344 residues with a calculated molecular mass of 38 032 Da. DNase II is a novel enzyme with no homologies to proteins of known function. Surprisingly, C. elegans appears to possess a family of DNase II homologs. Unlike DNase I-like enzymes that have tissue-specific expression patterns, huDNase II is ubiquituously expressed at low levels. When huDNase II is expressed in human 293 cells, we observe secretion of a novel 42-44 kDa glycoprotein; approximately 20-30% of recombinant human DNase II activity is secreted in this system. The secreted enzyme possesses DNA hydrolytic activity and shares biochemical properties with purified DNase II obtained from other species. We also show that the mechanism by which DNase II cuts DNA is similar to DNase I in that the enzyme produces nicks rather than double-strand cuts.
我们已经克隆并测序了编码人和鼠酸性脱氧核糖核酸酶II（DNase II）的新cDNA。序列分析预测，人DNase II含有一个N端信号序列，成熟的DNase II有344个氨基酸残基，计算分子量为38032Da。DNase II是一种新型酶，与已知功能的蛋白质无同源性。令人惊讶的是，秀丽隐杆线虫似乎拥有一个DNase II同源物家族。与具有组织特异性表达模式的DNase I样酶不同，人DNase II在所有组织中均低水平表达。当人DNase II在人293细胞中表达时，我们观察到一种新的42 - 44kDa糖蛋白的分泌；在该系统中约20 - 30%的重组人DNase II活性被分泌。分泌的酶具有DNA水解活性，并与从其他物种获得的纯化DNase II具有共同的生化特性。我们还表明，DNase II切割DNA的机制与DNase I相似，即该酶产生切口而非双链切割。
