Membrane-active Polymers: NCMNP13-x, NCMNP21-x and NCMNP21b-x for Membrane Protein Structural Biology

Abstract

Membrane proteins are a ubiquitous group of bio-macromolecules responsible for many crucial biological processes and serve as drug targets for a wide range of modern drugs. Detergent-free technologies such as styrene-maleic acid lipid particles (SMALP), diisobutylene-maleic acid lipid particles (DIBMALP), and native cell membrane nanoparticles (NCMN) systems have recently emerged as revolutionary alternatives to the traditional detergent-based approaches for membrane protein research. NCMN systems aim to create a membrane-active polymer library suitable for high-resolution structure determination. Herein, we report our design, synthesis, characterization and comparative application analyses of three novel classes of NCMN polymers, NCMNP13-x, NCMNP21-x and NCMNP21b-x. Although each NCMN polymer can solubilize various model membrane proteins and conserve native lipids into NCMN particles, only the NCMNP21b-x series reveals lipid-protein particles with good buffer compatibility and high homogeneity suitable for single-particle cryo-EM analysis. Consequently, the NCMNP21b-x polymers that bring out high-quality NCMN particles are particularly attractive for membrane protein structural biology. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=154 SRC="FIGDIR/small/475744v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@dbc1f3org.highwire.dtl.DTLVardef@19a5ff0org.highwire.dtl.DTLVardef@10beceorg.highwire.dtl.DTLVardef@15ec66a_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIDemonstrate straightforward strategies for tailoring styrene-maleic co-polymer (SMA) that revealed novel buffer compatible polymers, NCMNP13-50, NCMNP21-20 and NCMNP21b-x. C_LIO_LIElucidate how modification factors alter the membrane-active properties of these polymers, i.e., membrane protein extraction efficiency, morphology, etc. C_LIO_LIProvide valuable insights into the rational design of membrane-active polymers for membrane protein structural biology. C_LIO_LINCMNP21b-x polymers are highly compatible with high-resolution structure determination using an emerging technique, cryo-EM. C_LI