G-quadruplexes can multimerize under certain conditions, but the sequence requirements of such structures are not well understood. In this study, we investigated the ability of all possible variants of the central tetrad in a monomeric, parallel-strand G-quadruplex to form higher-order structures. Although most of these 256 variants existed primarily as monomers under the conditions of our screen, ∼10% formed dimers or tetramers. These structures could form in a wide range of monovalent and divalent metal ions, and folding was highly cooperative in both KCl and MgCl₂. As was previously shown for G-quadruplexes that bind GTP and promote peroxidase reactions, G-quadruplexes that form dimers and tetramers have distinct sequence requirements. Some mutants could also form heteromultimers, and a second screen was performed to characterize the sequence requirements of these structures. Taken together, these experiments provide new insights into the sequence requirements and structures of both homomultimeric and heteromultimeric G-quadruplexes.

中文翻译：

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G-四链体的多聚化规则

G-四链体可以在某些条件下多聚，但是这种结构的序列要求尚不十分清楚。在这项研究中，我们研究了在单体，平行链G-四链体中中心四联体的所有可能变体形成高阶结构的能力。尽管在我们筛选的条件下，这256个变体中的大多数主要以单体形式存在，但约有10％形成了二聚体或四聚体。这些结构可以在广泛的一价和二价金属离子中形成，并且折叠在KCl和MgCl ₂中都高度协作。如先前针对结合GTP并促进过氧化物酶反应的G-四链体所显示的，形成二聚体和四聚体的G-四链体具有不同的序列要求。一些突变体也可以形成异源多聚体，并进行第二次筛选以表征这些结构的序列要求。综上所述，这些实验提供了对同多聚体和异多聚体G-四链体的序列要求和结构的新见解。