Nitric oxide blocks cellular heme insertion into a broad range of heme proteins.
Although the insertion of heme into proteins enables their function in bioenergetics, metabolism, and signaling, the mechanisms and regulation of this process are not fully understood. We developed a means to study cellular heme insertion into apo-protein targets over a 3-h period and then investigated how nitric oxide (NO) released from a chemical donor (NOC-18) might influence heme (protoporphyrin IX) insertion into seven targets that present a range of protein structures, heme ligation states, and functions (three NO synthases, two cytochrome P450's, catalase, and hemoglobin). NO blocked cellular heme insertion into all seven apo-protein targets. The inhibition occurred at relatively low (nM/min) fluxes of NO, was reversible, and did not involve changes in intracellular heme levels, activation of guanylate cyclase, or inhibition of mitochondrial ATP production. These aspects and the range of protein targets suggest that NO can act as a global inhibitor of heme insertion, possibly by inhibiting a common step in the process.
Waheed
Syed Mohsin
SM
Department of Pathobiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH 44195, USA.
Ghosh
Arnab
A
Chakravarti
Ritu
R
Biswas
Ashis
A
Haque
Mohammad Mahfuzul
MM
Panda
Koustubh
K
Stuehr
Dennis J
DJ
D000818:Animals; D002374:Catalase / Q000096:biosynthesis; D002460:Cell Line; D019389:Cytochrome P-450 CYP2D6 / Q000096:biosynthesis; D051544:Cytochrome P-450 CYP3A / Q000096:biosynthesis; D006418:Heme / Q000378:metabolism*; D006420:Hemeproteins / Q000096:biosynthesis*; D006801:Humans; D020014:K562 Cells; D051379:Mice; D009569:Nitric Oxide / Q000494:pharmacology*; D052248:Nitric Oxide Synthase Type I / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D009603:Nitroso Compounds; D011524:Protoporphyrins / Q000378:metabolism*
D006420:Hemeproteins; C093285:NOC 18; D009603:Nitroso Compounds; D011524:Protoporphyrins; D009569:Nitric Oxide; D006418:Heme; C028025:protoporphyrin IX; D002374:Catalase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D019389:Cytochrome P-450 CYP2D6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human