caa a22 4500 60550704X CHVBK 20210128100630.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00775-015-1278-y doi (NATIONALLICENCE)springer-10.1007/s00775-015-1278-y Hydrogen bonding of the dissociated histidine ligand is not required for formation of a proximal NO adduct in cytochrome c' [Elektronische Daten] [Dlzar Ghafoor, Demet Kekilli, Gaylany Abdullah, Florian Dworkowski, Hamid Hassan, Michael Wilson, Richard Strange, Michael Hough] Cytochromes c', that occur in methanotrophic, denitrifying and photosynthetic bacteria, form unusual proximal penta-coordinate NO complexes via a hexa-coordinate distal NO intermediate. Their NO binding properties are similar to those of the eukaryotic NO sensor, soluble guanylate cyclase, for which they provide a valuable structural model. Previous studies suggested that hydrogen bonding between the displaced proximal histidine (His120) ligand (following its dissociation from heme due to trans effects from the distally bound NO) and a conserved aspartate residue (Asp121) could play a key role in allowing proximal NO binding to occur. We have characterized three variants of Alcaligenes xylosoxidans cytochrome c' (AXCP) where Asp121 has been replaced by Ala, Ile and Gln, respectively. In all variants, hydrogen bonding between residue 121 and His120 is abolished yet 5-coordinate proximal NO species are still formed. Our data therefore demonstrate that the His120-Asp121 bond is not essential for proximal NO binding although it likely provides an energy minimum for the displaced His ligand. All variants have altered proximal pocket structure relative to native AXCP. SBIC, 2015 Cytochrome nationallicence Nitric oxide nationallicence X-ray crystallography nationallicence Resonance Raman nationallicence Spectroscopy nationallicence Ligand binding nationallicence CytCp : Cytochrome c' nationallicence AXCP : Alcaligenes xylosoxidans cytochrome c' nationallicence SFCP : Shewanella frigidimarina cytochrome c' nationallicence SLS : Swiss Light Source nationallicence 5c : 5-Coordinate nationallicence 6c : 6-Coordinate nationallicence Ghafoor Dlzar Faculty of Science and Education Science, University of Sulaimani, Sulaymaniyah, Iraq aut Kekilli Demet School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut Abdullah Gaylany Medical Research Center, Hawler Medical University, Erbil, Iraq aut Dworkowski Florian Swiss Light Source, Paul Scherrer Institute (PSI), 5232, Villigen, Switzerland aut Hassan Hamid College of Ibn-Alhaitham, University of Baghdad, Baghdad, Iraq aut Wilson Michael School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut Strange Richard School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut Hough Michael School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut JBIC Journal of Biological Inorganic Chemistry Springer Berlin Heidelberg 20/6(2015-09-01), 949-956 0949-8257 20:6<949 2015 20 775 https://doi.org/10.1007/s00775-015-1278-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00775-015-1278-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ghafoor Dlzar Faculty of Science and Education Science, University of Sulaimani, Sulaymaniyah, Iraq aut NATIONALLICENCE 700 1- Kekilli Demet School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut NATIONALLICENCE 700 1- Abdullah Gaylany Medical Research Center, Hawler Medical University, Erbil, Iraq aut NATIONALLICENCE 700 1- Dworkowski Florian Swiss Light Source, Paul Scherrer Institute (PSI), 5232, Villigen, Switzerland aut NATIONALLICENCE 700 1- Hassan Hamid College of Ibn-Alhaitham, University of Baghdad, Baghdad, Iraq aut NATIONALLICENCE 700 1- Wilson Michael School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut NATIONALLICENCE 700 1- Strange Richard School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut NATIONALLICENCE 700 1- Hough Michael School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK aut NATIONALLICENCE 773 0- JBIC Journal of Biological Inorganic Chemistry Springer Berlin Heidelberg 20/6(2015-09-01), 949-956 0949-8257 20:6<949 2015 20 775