An isoprenylation and palmitoylation motif promotes intraluminal vesicle delivery of proteins in cells from distant species

PLoS One. 2014 Sep 10;9(9):e107190. doi: 10.1371/journal.pone.0107190. eCollection 2014.

Abstract

The C-terminal ends of small GTPases contain hypervariable sequences which may be posttranslationally modified by defined lipid moieties. The diverse structural motifs generated direct proteins towards specific cellular membranes or organelles. However, knowledge on the factors that determine these selective associations is limited. Here we show, using advanced microscopy, that the isoprenylation and palmitoylation motif of human RhoB (-CINCCKVL) targets chimeric proteins to intraluminal vesicles of endolysosomes in human cells, displaying preferential co-localization with components of the late endocytic pathway. Moreover, this distribution is conserved in distant species, including cells from amphibians, insects and fungi. Blocking lipidic modifications results in accumulation of CINCCKVL chimeras in the cytosol, from where they can reach endolysosomes upon release of this block. Remarkably, CINCCKVL constructs are sorted to intraluminal vesicles in a cholesterol-dependent process. In the lower species, neither the C-terminal sequence of RhoB, nor the endosomal distribution of its homologs are conserved; in spite of this, CINCCKVL constructs also reach endolysosomes in Xenopus laevis and insect cells. Strikingly, this behavior is prominent in the filamentous ascomycete fungus Aspergillus nidulans, in which GFP-CINCCKVL is sorted into endosomes and vacuoles in a lipidation-dependent manner and allows monitoring endosomal movement in live fungi. In summary, the isoprenylated and palmitoylated CINCCKVL sequence constitutes a specific structure which delineates an endolysosomal sorting strategy operative in phylogenetically diverse organisms.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Aspergillus nidulans / genetics
  • Aspergillus nidulans / metabolism
  • Biological Transport
  • Conserved Sequence
  • Endocytosis
  • Endosomes / metabolism
  • Female
  • Fibroblasts / cytology
  • Fibroblasts / metabolism*
  • HeLa Cells
  • Humans
  • Lipoylation
  • Lysosomes / metabolism
  • Molecular Sequence Data
  • Moths / cytology
  • Moths / metabolism
  • Ovary / cytology
  • Ovary / metabolism
  • Prenylation
  • Primary Cell Culture
  • Protein Processing, Post-Translational*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Sequence Homology, Amino Acid
  • Transport Vesicles / metabolism*
  • Xenopus laevis / genetics
  • Xenopus laevis / metabolism
  • rhoB GTP-Binding Protein / genetics
  • rhoB GTP-Binding Protein / metabolism*

Substances

  • Recombinant Fusion Proteins
  • rhoB GTP-Binding Protein

Grants and funding

This work was supported by grants SAF2009-11642 and SAF2012-36519 from MINECO and RETIC RD12/0013/0008 to DPS, grants BIO2012-30695 from MINECO and S2010/BMD-2414 from Comunidad de Madrid to MAP, and grants from the Norwegian Cancer Society and the South-Eastern Norway Regional Health Authority to HS. CLO is supported by the FPI program from MINECO (BES-2010-033718). The stay of CLO at HS laboratory was supported by the short stay grant EEBB-I-12-04482 from MINECO. J. Martínez Turrión has been the recipient of a JAE Intro Fellowship from CSIC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.