Native Electron Capture Dissociation Maps to Iron-Binding Channels in Horse Spleen Ferritin

Owen S. Skinner*, Michael O. McAnally, Richard P. Van Duyne, George C. Schatz, Kathrin Breuker, Philip D. Compton, Neil L. Kelleher

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Native electron capture dissociation (NECD) is a process during which proteins undergo fragmentation similar to that from radical dissociation methods, but without the addition of exogenous electrons. However, after three initial reports of NECD from the cytochrome c dimer complex, no further evidence of the effect has been published. Here, we report NECD behavior from horse spleen ferritin, a ∼490 kDa protein complex ∼20-fold larger than the previously studied cytochrome c dimer. Application of front-end infrared excitation (FIRE) in conjunction with low- and high-m/z quadrupole isolation and collisionally activated dissociation (CAD) provides new insights into the NECD mechanism. Additionally, activation of the intact complex in either the electrospray droplet or the gas phase produced c-type fragment ions. Similar to the previously reported results on cytochrome c, these fragment ions form near residues known to interact with iron atoms in solution. By mapping the location of backbone cleavages associated with c-type ions onto the crystal structure, we are able to characterize two distinct iron binding channels that facilitate iron ion transport into the core of the complex. The resulting pathways are in good agreement with previously reported results for iron binding sites in mammalian ferritin. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)10711-10716
Number of pages6
JournalAnalytical Chemistry
Volume89
Issue number20
DOIs
StatePublished - Oct 17 2017

Funding

The authors acknowledge generous support from the W. M. Keck Foundation (DT061512). OSS and MOM are supported by National Science Foundation Graduate Research Fellowships (2014171659 and DGE-0824162, respectively). KB is supported by FWF projects Y372 and P27347. The authors would also like to acknowledge helpful insight from Eva-Maria Schneeberger and Nicole Haverland.

ASJC Scopus subject areas

  • Analytical Chemistry

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