5nc0 | pdb_00005nc0

The 0.91 A resolution structure of the L16G mutant of cytochrome c prime from Alcaligenes xylosoxidans, complexed with nitric oxide

spinqualitylabelsall models 5nc0, resolution 0.91Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5nc0 is a 1 chain structure with sequence from "achromobacter_xylosoxidans"_yabuuchi_and_ohyama_1971 "achromobacter xylosoxidans" yabuuchi and ohyama 1971. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: EDO, HEC, NO, NO2, NO3, SO4 NonStd Res: PCA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [CYCP_ALCXX] Cytochrome c' is the most widely occurring bacterial c-type cytochrome. Cytochromes c' are high-spin proteins and the heme has no sixth ligand. Their exact function is not known. Publication Abstract from PubMed Nitrite coordination to heme cofactors is a key step in the anaerobic production of the signaling molecule nitric oxide (NO). An ambidentate ligand, nitrite has the potential to coordinate via the N- (nitro) or O- (nitrito) atoms in a manner that can direct its reactivity. Distinguishing nitro vs nitrito coordination, along with the influence of the surrounding protein, is therefore of particular interest. In this study, we probed Fe(III) heme-nitrite coordination in Alcaligenes xylosoxidans cytochrome c' (AXCP), an NO carrier that excludes anions in its native state but that readily binds nitrite (Kd approximately 0.5 mM) following a distal Leu16 --> Gly mutation to remove distal steric constraints. Room-temperature resonance Raman spectra (407 nm excitation) identify nu(Fe-NO2), delta(ONO), and nus(NO2) nitrite ligand vibrations in solution. Illumination with 351 nm UV light results in photoconversion to {FeNO}(6) and {FeNO}(7) states, enabling FTIR measurements to distinguish nus(NO2) and nuas(NO2) vibrations from differential spectra. Density functional theory calculations highlight the connections between heme environment, nitrite coordination mode, and vibrational properties and confirm that nitrite binds to L16G AXCP exclusively through the N atom. Efforts to obtain the nitrite complex crystal structure were hampered by photochemistry in the X-ray beam. Although low dose crystal structures could be modeled with a mixed nitrite (nitro)/H2O distal population, their photosensitivity and partial occupancy underscores the value of the vibrational approach. Overall, this study sheds light on steric determinants of heme-nitrite binding and provides vibrational benchmarks for future studies of heme protein nitrite reactions. Distinguishing Nitro vs Nitrito Coordination in Cytochrome c' Using Vibrational Spectroscopy and Density Functional Theory.,Nilsson ZN, Mandella BL, Sen K, Kekilli D, Hough MA, Moenne-Loccoz P, Strange RW, Andrew CR Inorg Chem. 2017 Nov 6;56(21):13205-13213. doi: 10.1021/acs.inorgchem.7b01945. PMID:29053273 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome C 3D structures

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