Force-induced melting of DNA--evidence for peeling and internal melting from force spectra on short synthetic duplex sequences.
Force-induced melting of DNA--evidence for peeling and internal melting from force spectra on short synthetic duplex sequences.
复制标题
DOI：
10.1093/nar/gku441
复制
发表时间：
2014-07
影响因子：
14.9
通讯作者：
Nordén B
中科院分区：
文献类型：
--
作者：
Bosaeus N;El-Sagheer AH;Brown T;Åkerman B;Nordén B
当扭转不受约束的双链DNA分子被其末端拉伸时，DNA的过度拉伸发生在约60-70 pN。在过渡期间，轮廓长度增加高达70%，而没有完全链解离。有三种机制被认为是相关的：力诱导的单链DNA融合，其中一条或两条链都带有张力，或者B到S的转变成为更长的，仍然是碱基配对的构象。我们拉伸序列设计的寡核苷酸，努力隔离这三个过程，专注于力诱导的熔化。通过在64 bp富含AT的双链体的一端或两端引入位点特异性链间交联，我们可以在5 mM和1 M单价盐下重复进行两个解链过程。我们发现，当一端是密封的AT丰富的序列经历剥离表现出滞后在低和高盐。当两个末端都被密封时，AT序列反而经历内部熔化。第三，剥离熔融研究在复合寡核苷酸，其中相同的AT丰富的序列连接到一个GC丰富的序列，已知进行B到S的过渡，而不是熔化。然后，构建体首先在富含AT的部分中熔化，随后在较高的力下在GC部分中由B到S转变，表明DNA过度拉伸模式是加性的。
Overstretching of DNA occurs at about 60–70 pN when a torsionally unconstrained double-stranded DNA molecule is stretched by its ends. During the transition, the contour length increases by up to 70% without complete strand dissociation. Three mechanisms are thought to be involved: force-induced melting into single-stranded DNA where either one or both strands carry the tension, or a B-to-S transition into a longer, still base-paired conformation. We stretch sequence-designed oligonucleotides in an effort to isolate the three processes, focusing on force-induced melting. By introducing site-specific inter-strand cross-links in one or both ends of a 64 bp AT-rich duplex we could repeatedly follow the two melting processes at 5 mM and 1 M monovalent salt. We find that when one end is sealed the AT-rich sequence undergoes peeling exhibiting hysteresis at low and high salt. When both ends are sealed the AT sequence instead undergoes internal melting. Thirdly, the peeling melting is studied in a composite oligonucleotide where the same AT-rich sequence is concatenated to a GC-rich sequence known to undergo a B-to-S transition rather than melting. The construct then first melts in the AT-rich part followed at higher forces by a B-to-S transition in the GC-part, indicating that DNA overstretching modes are additive.
登录
查看更多内容
影响因子：
56.9
作者：
Cluzel, P;Lebrun, A;Caron, F
通讯作者：
Caron, F
影响因子：
3.4
作者：
Bianco, Pasquale;Bongini, Lorenzo;Lombardi, Vincenzo
通讯作者：
Lombardi, Vincenzo
影响因子：
6.8
作者：
Killian, Jessica L.;Li, Ming;Wang, Michelle D.
通讯作者：
Wang, Michelle D.
影响因子：
8.6
作者：
Léger, JF;Romano, G;Marko, JF
通讯作者：
Marko, JF
影响因子：
14.9
作者：
Bongini L;Melli L;Lombardi V;Bianco P
通讯作者：
Bianco P