title: Analysis of methanobactin from Methylosinus trichosporium OB3b via ion mobility mass spectrometry.
abstract: Methanobactins (mbs) are Low molecular mass copper binding chromopeptides analogous to pyoverdin class iron-binding siderophores. Mb produced by Methylosinus trichosporium OB3b (mb-oB3b) has been used as a model molecuLe for methanobactin although the amino acid sequence of mb-OB3b differs significantly from other characterized mbs. In particular, there is the presence of a pair of cystine residues which are absent in other characterized mbs. The role of the Cys3-Cys6 in copper binding, Cu(ll) reduction and its role on the mb-OB3b structure remains in debate. Here, we use a single-step dithiothreitol treatment as an effective method in reducing the disulfide bond allowing in-depth ion mobility-mass spectrometry (IM-MS) analysis. The IM-MS results show mb-oB3b exists in the gas-phase as three different negatively-charged states and exists in multiple conformational states, when introduced via electrospray ionization from aqueous solution near physiological pH. The disulfide bond serves a structural role and is not involved in the Cu(I/ll) binding capability of mb-OB3b, with the binding of a second Cu(I/ll) related to a further deprotonation of mb-OB3b. Overall, these findings are in good correlation with expected solution-phase behavior of mb-OB3b. The results suggest IM-MS is an effective tool for better understanding the complex nature of this intriguing peptide.
authors: Department of BioLogical & Environmental Sciences, Texas A&M University-Commerce, 2600 S Neat St., Commerce. TX 75428, USA.
authors: DongWon
authors: D
authors: Choi
authors: Ramakrishna
authors: R
authors: Sesham
authors: Yuri
authors: Y
authors: Kim
authors: Laurence A
authors: LA
authors: Angel
mesh_terms: D001665:Binding Sites; D003300:Copper / Q000378:metabolism*; D004220:Disulfides / Q000737:chemistry; D004229:Dithiothreitol / Q000737:chemistry; D004867:Equipment Design; D007093:Imidazoles / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D020602:Methylosinus trichosporium / Q000737:chemistry* / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods
chemical_list: D004220:Disulfides; D007093:Imidazoles; D009842:Oligopeptides; C491147:methanobactin; D003300:Copper; D004229:Dithiothreitol