Nucleotidyl Cyclase Activity of Soluble Guanylyl Cyclase α₁β₁

Abstract

Soluble guanylyl cyclase (sGC) regulates several important physiological processes by converting GTP into the second-messenger cGMP. sGC has several structural and functional properties in common with adenylyl cyclases (ACs). Recently, we reported that membranous ACs and sGC are potently inhibited by 2',3'-O-(2,4,6-trinitrophenyl)-substituted purine and pyrimidine nucleoside 5'-triphosphates. Using a highly sensitive high-performance liquid chromatography-tandem mass spectrometry method, we report that highly purified recombinant sGC of rat possesses nucleotidyl cyclase activity. As opposed to GTP, ITP, XTP and ATP, the pyrimidine nucleotides UTP and CTP were found to be sGC substrates in the presence of Mn(2+). When Mg(2+) is used, sGC generates cGMP, cAMP, cIMP, and cXMP. In conclusion, soluble "guanylyl" cyclase possesses much broader substrate specificity than previously assumed. Our data have important implications for cyclic nucleotide-mediated signal transduction.

cIMP synthesized by sGC as a mediator of hypoxic contraction of coronary arteries

“…Due to insufficient sensitivity and specificity of the detection methods, it has only recently become obvious that sGC possesses much broader substrate specificity than previously assumed (4). Thus, using a highly sensitive and specific HPLC tandem mass spectrometry (HPLC-MS/MS) method, Seifert and colleagues (4) demonstrated that, in addition to cGMP, purified rat sGC can generate six different cyclic nucleotides. Among them, the formation rate of inosine 3=,5=-cyclic monophosphate (cIMP) is substantially greater than that of the other cyclic nucleotides except cGMP (4).…”

“…Thus, using a highly sensitive and specific HPLC tandem mass spectrometry (HPLC-MS/MS) method, Seifert and colleagues (4) demonstrated that, in addition to cGMP, purified rat sGC can generate six different cyclic nucleotides. Among them, the formation rate of inosine 3=,5=-cyclic monophosphate (cIMP) is substantially greater than that of the other cyclic nucleotides except cGMP (4). The present study was designed to determine whether or not cIMP may act as the mediator for the above-mentioned endothelium-dependent hypoxic augmentation of vasoconstriction.…”

PDE7A1 hydrolyzes cCMP

“…The lack of sensitive detection methods hampered research activity in this field for many years. With the advent of highly sensitive and selective mass spectrometry-based detection systems [3], it became possible to detect even very low concentrations of cyclic pyrimidine nucleotides in cells, tissues and enzymatically digested samples [4,5]. cCMP is synthesized by soluble adenylyl cyclase [4], by soluble guanylyl cyclase [6] and by the Pseudomonas aeruginosa exotoxin ExoY [7].…”

Recent progress in the field of cIMP research

“…In vitro studies with highly purified sGC and sensitive and specific mass spectrometry methods have unequivocally shown that in addition to cGMP, sGC is also capable of effectively producing inosine 3′,5′cyclic monophosphate (cIMP) (Beste et al, 2012). pGCs generate cIMP as well (Beste et al, 2013).…”