Abstract
Zinc modulates the biological function of histidine-rich glycoprotein (HRG) through binding to its His-rich region (HRR). The Zn2+-binding properties of a 35 amino-acid biologically-active peptide mimic of the HRR, HRGP330, were investigated using dissociative mass spectrometry approaches in addition to travelling-wave ion mobility mass spectrometry (TWIM-MS). Native mass spectrometry confirmed zinc binding to HRGP330; however, broadening of the 1H NMR resonances upon addition of Zn2+ ions precluded the attainment of structural information. A complementary approach employing TWIM-MS indicated that HRGP330 has a more compact structure in the presence of Zn2+ ions. Top-down MS/MS data supported a metal-binding-induced conformational change, as fewer fragments were observed for Zn2+-bound HRGP330. Zn2+-bound fragments of both N-terminal and C-terminal ends of the peptide were identified from collision-induced dissociation (CID) and electron transfer dissociation/proton transfer reaction (ETD/PTR) experiments, suggesting that multiple binding sites exist within this region of HRG. The combination of mass spectrometry and NMR approaches provides new insight into the highly dynamic interaction between zinc and this His-rich peptide.
Highlights
Histidine-rich peptides, loops and regions are ubiquitous in the proteomes of all organisms[1,2]
The broad-spectrum antimicrobial activities of histidine-rich glycoprotein (HRG) and HRG-derived His-rich peptides are Zn2+ dependent[13]. These findings suggest that peptides which correspond to particular sections of the His-rich region (HRR) mimic some of the molecular properties associated with HRG or its large proteolytic fragment
Crude synthetic HRGP330 was purified by Reverse-Phase-HPLC (Supplementary Fig. S1) and its identity was confirmed by ESI-MS
Summary
Histidine-rich peptides, loops and regions are ubiquitous in the proteomes of all organisms[1,2]. An important property of His-rich proteins and peptides is their ability to bind metal ions, and in many cases, this ability relates to their biological function In organisms, they are predominantly associated with Ni2+, Cu2+, and Zn2+ 1. Other binding partners include heparins and heparan sulfate[21], heme[22,23], and metal cations such as Cu2+ and Zn2+ 24 In this context, the HRR is a interesting part of the protein, as are the imidazole nitrogens of this region thought to play a major role in Zn2+ binding, but the latter has been shown to enhance many of the reported HRG-ligand interactions, at physiologically relevant concentrations[25,26,27,28,29,30].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
