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Impact of arginine–phosphate interactions on the reentrant condensation of disordered proteins

DOI: 10.1021/acs.biomac.0c01765 DOI Help

Authors: Samuel Lenton (Lund University) , Stefan Hervø-Hansen (Lund University) , Anton M. Popov (European Synchroton Radiation Facility) , Mark D. Tully (European Synchrotron Radiation Facility (ESRF)) , Mikael Lund (Lund University; LINXS—Lund Institute of Advanced Neutron and X-ray Science) , Marie Skepö (Lund University; LINXS—Lund Institute of Advanced Neutron and X-ray Science)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biomacromolecules

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 24294

Open Access Open Access

Abstract: Re-entrant condensation results in the formation of a condensed protein regime between two critical ion concentrations. The process is driven by neutralization and inversion of the protein charge by oppositely charged ions. Re-entrant condensation of cationic proteins by the polyvalent anions, pyrophosphate and tripolyphosphate, has previously been observed, but not for citrate, which has similar charge and size compared to the polyphosphates. Therefore, besides electrostatic interactions, other specific interactions between the polyphosphate ions and proteins must contribute. Here, we show that additional attractive interactions between arginine and tripolyphosphate determine the re-entrant condensation and decondensation boundaries of the cationic, intrinsically disordered saliva protein, histatin 5. Furthermore, we show by small-angle X-ray scattering (SAXS) that polyvalent anions cause compaction of histatin 5, as would be expected based solely on electrostatic interactions. Hence, we conclude that arginine–phosphate-specific interactions not only regulate solution properties but also influence the conformational ensemble of histatin 5, which is shown to vary with the number of arginine residues. Together, the results presented here provide further insight into an organizational mechanism that can be used to tune protein interactions in solution of both naturally occurring and synthetic proteins.

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: B21-High Throughput SAXS

Other Facilities: BM29 at ESRF

Added On: 28/03/2021 10:43


Discipline Tags:

Life Sciences & Biotech Chemistry Biochemistry

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)