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In enzymology, diguanylate cyclase, also known as diguanylate kinase (), is an enzyme that catalyzes the chemical reaction: 2 Guanosine triphosphate ↔ 2 diphosphate + cyclic di-3',5'-guanylate The substrates of diguanylate cyclases (DGCs) are two molecules of guanosine triphosphate (GTP) and the products are two molecules of diphosphate and one molecule of cyclic di-3’,5’-guanylate (cyclic di-GMP). Degradation of cyclic di-GMP to guanosine monophosphate (GMP) is catalyzed by a phosphodiesterase (PDE). == Structure == Diguanylate cyclases are characterized by the conserved amino acid sequence motifs “GGDEF” (Gly-Gly-Asp-Glu-Phe) or “GGEEF” (Gly-Gly-Glu-Glu-Phe), which constitute the domain of the DGC active site.〔 〕 These domains are often found coupled to other signaling domains within multidomain proteins. Often, GGDEF domains with DGC activity are found in the same proteins as c-di-GMP-specific phosphodiesterase (PDE) EAL (Glu-Ala-Leu) domains.〔 〕〔 〕 DGC is thought to only be active as a dimer consisting of two subunits, both with GGDEF domains.〔 〕 The active (or catalytic) site is located at the interface between the two subunits, each binding one molecule of GTP. (See Activation mechanism and Regulation section for more information) Weak sequence similarity and pronounced secondary structure similarity between GGDEF domains and the catalytic domains of adenylate cyclases (AC) have led to the hypothesis that DGCs and ACs share a similar fold.〔 〕 This was verified with the resolution of the crystal structure of the DGC PleD from ''Caulobacter crescentus'' in complex with c-di-GMP.〔 As shown in the figure, active PleD, shown as a dimer, is composed of the catalytic DCG domain (labeled DGC) and two CheY-like receiver domains (labeled D1/D2). The DGC domain of each subunit is linked to the two CheY-like domains by a flexible peptide linkage chain.〔 The DCG domain closely resembles the domain of the AC catalytic core which consists of a five-stranded β-sheet surrounded by helices. As of mid-2011, 11 crystal structures of confirmed or putative DGCs have been solved, with PDB accession codes , , , , , , , , , , and . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「diguanylate cyclase」の詳細全文を読む スポンサード リンク
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