The Remorin C-terminal Anchor was shaped by convergent evolution among membrane binding domains

Abstract

StREM1.3 Remorin is a well-established plant raftophilic protein, predominantly associated with sterol- and sphingolipid-rich membrane rafts. We recently identified a C-terminal domain (RemCA) required and sufficient for StREM1.3 anchoring to the plasma membrane. Here, we report a search for homologs and analogs of RemCA domain in publicly available protein sequence and structure databases. We could not identify RemCA homologous domains outside the Remorin family but we identified domains sharing bias in amino-acid composition and predicted structural fold with RemCA in bacterial, viral and animal proteins. These results suggest that RemCA emerged by convergent evolution among unrelated membrane binding domain.

Keywords: convergent evolution; lipid rafts; membrane anchor; remorin.

Figure 1. Diversity of RemCA domains across the plant kingdom and the identification of analogous membrane binding domains. (A) Natural diversity and conservation in the RemCA sequence illustrated by a sequence logo based on the alignment of 117 RemCA peptides from 26 plant species. (B) Analysis of bias in amino acid composition found in RemCA sequences. Frequencies are given as the average number of amino acids per 28 amino-acid long peptides in RemCA (Y-axis) or random 28- amino-acid long peptides extracted from the Uniprot database (Y-axis). (C) Two examples of membrane binding domains analogs of RemCA domain. The domains are shown in the context of the full-length protein structure (left) and superimposed with StREM1.3 RemCA model (right).