Intracellular formation of "undisruptable" dimers of inducible nitric oxide synthase
Intracellular formation of "undisruptable" dimers of inducible nitric oxide synthase
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DOI：
10.1073/pnas.2435290100
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发表时间：
2003-11-25
影响因子：
11.1
通讯作者：
Eissa, NT
中科院分区：
文献类型：
--
作者：
Kolodziejski, PJ;Rashid, MB;Eissa, NT
诱导型一氧化氮合酶（inducible NO synthase，iNOS）过度产生一氧化氮（nitric oxide，NO）参与了多种疾病的发病机制。NOS仅作为同二聚体具有活性。NOS的二聚化代表了治疗干预的潜在关键靶点。在这项研究中，我们表明，细胞内的NOS形式的二聚体是“不可破坏的”沸腾，变性剂，或还原剂。不可破坏的（LID）二聚体是明显区别于容易解离的二聚体形成的NOS在体外。UD二聚体在大肠杆菌表达的NOS中不形成，并且不能在体外组装，这表明它们的形成需要体内细胞过程。NOS UD二聚体不受H4 B细胞内耗竭的影响。然而，Cys-115（对锌结合至关重要）的突变极大地影响UD二聚体的形成。本研究揭示了体内iNOS二聚体形成的机制。UD二聚体代表一类未被怀疑的NOS二聚体。这一出乎意料的发现修正了我们对iNOS二聚化机制的理解，并为未来旨在调节体内iNOS活性的研究奠定了基础。
Overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) has been implicated in the pathogenesis of many diseases. NOS is active only as a homodimer. Dimerization of NOS represents a potentially critical target for therapeutic intervention. In this study, we show that intracellular NOS forms dimers that are "undisruptable" by boiling, denaturants, or reducing agents. Undisruptable (LID) dimers are clearly distinguishable from the easily dissociated dimers formed by NOS in vitro. UD dimers do not form in Escherichia coli-expressed NOS and could not be assembled in vitro, which suggests that an in vivo cellular process is required for their formation. NOS UD dimers are not affected by intracellular depletion of H4B. However, the mutation of Cys-115 (critical for zinc binding) greatly affects the formation of UD dimers. This study reveals insight into the mechanisms of in vivo iNOS dimer formation. UD dimers represent a class of NOS dimers that had not been suspected. This unanticipated finding revises our understanding of the mechanisms of iNOS dimerization and lays the groundwork for future studies aimed at modulating iNOS activity in vivo.