The C-terminal sequence of RhoB directs protein degradation through an endo-lysosomal pathway.
BACKGROUND
Protein degradation is essential for cell homeostasis. Targeting of proteins for degradation is often achieved by specific protein sequences or posttranslational modifications such as ubiquitination.


RESULTS
By using biochemical and genetic tools we have monitored the localization and degradation of endogenous and chimeric proteins in live primary cells by confocal microscopy and ultra-structural analysis. Here we identify an eight amino acid sequence from the C-terminus of the short-lived GTPase RhoB that directs the rapid degradation of both RhoB and chimeric proteins bearing this sequence through a lysosomal pathway. Elucidation of the RhoB degradation pathway unveils a mechanism dependent on protein isoprenylation and palmitoylation that involves sorting of the protein into multivesicular bodies, mediated by the ESCRT machinery. Moreover, RhoB sorting is regulated by late endosome specific lipid dynamics and is altered in human genetic lipid traffic disease.


CONCLUSIONS
Our findings characterize a short-lived cytosolic protein that is degraded through a lysosomal pathway. In addition, we define a novel motif for protein sorting and rapid degradation, which allows controlling protein levels by means of clinically used drugs.
Pérez-Sala
Dolores
D
Department of Chemical and Physical Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain. dperezsala@cib.csic.es
Boya
Patricia
P
Ramos
Irene
I
Herrera
Mónica
M
Stamatakis
Konstantinos
K
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism* / Q000648:ultrastructure; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism; D008247:Lysosomes / Q000378:metabolism* / Q000648:ultrastructure; D051379:Mice; D008969:Molecular Sequence Data; D057146:Multivesicular Bodies / Q000648:ultrastructure; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals; D055550:Protein Stability; D021381:Protein Transport; D013329:Structure-Activity Relationship; D013347:Subcellular Fractions / Q000378:metabolism; D020743:rhoB GTP-Binding Protein / Q000737:chemistry* / Q000378:metabolism*
D056827:Endosomal Sorting Complexes Required for Transport; D021382:Protein Sorting Signals; D049452:Green Fluorescent Proteins; D020743:rhoB GTP-Binding Protein