Single-stranded DNA structures play a significant role in biological systems, in particular during replication, translation, and DNA repair. Tracts of simple repetitive DNA are associated with slipped-strand mispairing, which can lead to genetic diseases. Recent NMR studies of TTTA and CCTG repeats have shown that these sequences form mini-dumbbells (MDBs), leading to frameshift mutations. Here we explore the energy landscapes of (CCTG)₂ and (TTTA)₂, which are currently the smallest known molecules to form MDBs. While (CCTG)₂ MDBs are stable, (TTTA)₂ exhibits numerous other structures with lower energies. A key factor identified in the stabilization of MDB structures is the bonding strength between residues 1 and 4, and 5 and 8.

中文翻译：

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迷你哑铃DNA八核苷酸的能量态势

单链DNA结构在生物系统中起着重要作用，尤其是在复制，翻译和DNA修复过程中。简单重复DNA的片段与链错配有关，可能导致遗传疾病。TTTA和CCTG重复序列的最新NMR研究表明，这些序列形成了微型哑铃（MDB），导致移码突变。在这里，我们探索（CCTG）₂和（TTTA）₂的能量分布，它们是目前形成MDB的已知最小分子。尽管（CCTG）₂ MDB稳定，但（TTTA）₂具有许多其他具有较低能量的结构。稳定MDB结构的关键因素是残基1和4、5和8之间的结合强度。