Membrane Shape Transformation Induced by Banana-Shaped Proteins

Shape deformations of biomembranes are controlled by various proteins. Many of theseproteins contain a binding module known as the BAR (Bin-Amphiphysin-Rvs) domain,which consists of a banana-shaped dimer. We have revealed anisotropic spontaneouscurvatures of banana-shaped domains induce assembly of the protein rods and changemembrane shapes using implicit-solvent meshless membrane simulations. The proteinrods cooperatively induce tubulation as well as formatin of percolated rod networks,striped bumps, polygonal tubes, and polyhedral vesicles [1-6].

Hiroshi NoguchiInstitute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan

noguchi@issp.u-tokyo.ac.jp

[1] H. Noguchi, EPL 108, 48001 (2014). [3] H. Noguchi, Sci. Rep. 6, 20935 (2016). [5] H. Noguchi and J.-B. Fournier, Soft Matter, 13, 4099 (2017).[2] H. Noguchi, J. Chem. Phys. 143, 243109 (2015). [4] H. Noguchi, Phys. Rev. E 93, 052404 (2016). [6] H. Noguchi, Soft Matter, 13, 7771 (2017).

BAR domain

McMahon & Gallop, Nature 438, 590 (2005).

φrod = 0.3 φrod = 0.4

tetrahedron

triangular prism0

0.5

1

5 10CrodRves

x

y

z

tri

dis

triangular hosohedron

elliptic disk

Formation of polyhedral vesicle

Membrane and Protein ModelsMembrane particles, which have orientationaldegrees of freedom, self-assemble to form one-layer membrane. A protein rod is modeled by alinear chain of membrane particles.No direct attractive interactions are takenbetween the rods. The rods are assembled bymembrane-mediated interactions.

1/Cside

1/Crod

Tubulation from Flat Membrane [3,6]

Csiderrod= -1

Percolated networks aretransiently formed at Cside< 0.

0

0.5

1

0 4000 8000t/τ

Csiderrod =

-1

0

1

0

0.5

1

Csiderrod = -1

0

1

3

4

-1 0 1Csiderrod

isolatetubulation

partial

network

Csiderrod= 1Tubulation via percolated network at high rod density φrod = 0.4

Acceleration of tubulation by addition of smallinclusions with isotropic spontaneous curvature

φrod = 0.1

straight clusterformation

budding

tubulation

random distribution

coexistence

Membrane Structures Induced byTwo Types of Protein Rods [5]

straightassembly

stripeassembly

Cr1rrod= 4Cr2= 0

Cr2rrod= -2 Cr2rrod= -3

Cr2rrod= -1

Two types of rods of opposite curavatures form straight andstripe bumps. Positive tension stabilizes stripe assembly.

surface tension

Rod Self-assembly on Vesicle [1-6]

rods of negativeside curvature

rods with isotropicinclusions two types of rods