Proline substitution of dimer interface β-strand residues as a strategy for the design of functional monomeric proteins

Prem Raj B Joseph, Krishna Mohan Poluri, Pavani Gangavarapu, Lavanya Rajagopalan, Sandeep Raghuwanshi, Ricardo M. Richardson, Roberto Garofalo, Krishna Rajarathnam

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Proteins that exist in monomer-dimer equilibrium can be found in all organisms ranging from bacteria to humans; this facilitates fine-tuning of activities from signaling to catalysis. However, studying the structural basis of monomer function that naturally exists in monomer-dimer equilibrium is challenging, and most studies to date on designing monomers have focused on disrupting packing or electrostatic interactions that stabilize the dimer interface. In this study, we show that disrupting backbone H-bonding interactions by substituting dimer interface β-strand residues with proline (Pro) results in fully folded and functional monomers, by exploiting proline's unique feature, the lack of a backbone amide proton. In interleukin-8, we substituted Pro for each of the three residues that form H-bonds across the dimer interface β-strands. We characterized the structures, dynamics, stability, dimerization state, and activity using NMR, molecular dynamics simulations, fluorescence, and functional assays. Our studies show that a single Pro substitution at the middle of the dimer interface β-strand is sufficient to generate a fully functional monomer. Interestingly, double Pro substitutions, compared to single Pro substitution, resulted in higher stability without compromising native monomer fold or function. We propose that Pro substitution of interface β-strand residues is a viable strategy for generating functional monomers of dimeric, and potentially tetrameric and higher-order oligomeric proteins.

Original languageEnglish (US)
Pages (from-to)1491-1501
Number of pages11
JournalBiophysical Journal
Volume105
Issue number6
DOIs
StatePublished - Sep 17 2013

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Proline
Proteins
Dimerization
Molecular Dynamics Simulation
Static Electricity
Catalysis
Interleukin-8
Amides
Protons
Fluorescence
Bacteria

ASJC Scopus subject areas

  • Biophysics

Cite this

Proline substitution of dimer interface β-strand residues as a strategy for the design of functional monomeric proteins. / Joseph, Prem Raj B; Poluri, Krishna Mohan; Gangavarapu, Pavani; Rajagopalan, Lavanya; Raghuwanshi, Sandeep; Richardson, Ricardo M.; Garofalo, Roberto; Rajarathnam, Krishna.

In: Biophysical Journal, Vol. 105, No. 6, 17.09.2013, p. 1491-1501.

Research output: Contribution to journalArticle

Joseph PRB, Poluri KM, Gangavarapu P, Rajagopalan L, Raghuwanshi S, Richardson RM et al. Proline substitution of dimer interface β-strand residues as a strategy for the design of functional monomeric proteins. Biophysical Journal. 2013 Sep 17;105(6):1491-1501. https://doi.org/10.1016/j.bpj.2013.08.008
Joseph, Prem Raj B ; Poluri, Krishna Mohan ; Gangavarapu, Pavani ; Rajagopalan, Lavanya ; Raghuwanshi, Sandeep ; Richardson, Ricardo M. ; Garofalo, Roberto ; Rajarathnam, Krishna. / Proline substitution of dimer interface β-strand residues as a strategy for the design of functional monomeric proteins. In: Biophysical Journal. 2013 ; Vol. 105, No. 6. pp. 1491-1501.
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