The goal of our program is to study key proteins involved in nitric oxide metabolism inPseudomonas aeruginosa during persistent infection. Our approach includes biochemical, structural biology and in vivo studies. Recent results include:
- Elucidation of the catalytic mechanism of NO synthesis and release by cd1 nitrite reductase (NiR). We have shown that NO release from reduced heme d1 (the active site of NiR) is fast and explained this observation in terms of the intrinsic properties of this peculiar cofactor and architecture of the heme pocket. See recent papers: Rinaldo et al 2011, Biochem J. 435(1):217-25; Radoul et al. 2011, JACS 133(9):3043-55. Castiglione et al 2012 Antioxid Redox Signal., 17(4):684-716;Rinaldo et al. 2014.Biochem Biophys Res Commun. 451(3):449-54.
- Understanding of the structure and function of DNR, the P.aeruginosa trascription factor acting as a master regulator of NO sensing. We have shown that DNR requires heme to sense NO both in vitro (Giardina et al 2008 J. Mol Biol. 378(5):1002-15) and in vivo (Castiglione et al. 2009, 155:2838-44). We have also shown that a large conformational change, involving ligand exchange, is required for DNR activation (Giardina et al. 2009, 77(1):174-80; Rinaldo et al 2012,Antioxid Redox Signal. 17(9):1178-89;Cutruzzolà et al. 2014 Biometals 27:763-73)