Faculty Collaboration Database

The chaperone protein SmgGDS interacts with small GTPases entering the prenylation pathway by recognizing the last amino acid in the CAAX motif. J Biol Chem 2014 Mar 07;289(10):6862-6876

Date

01/15/2014

Pubmed ID

24415755

Pubmed Central ID

PMC3945348

DOI

10.1074/jbc.M113.527192

Scopus ID

2-s2.0-84896783691 (requires institutional sign-in at Scopus site)   34 Citations

Abstract

Ras family small GTPases localize at the plasma membrane, where they can activate oncogenic signaling pathways. Understanding the mechanisms that promote membrane localization of GTPases will aid development of new therapies to inhibit oncogenic signaling. We previously reported that SmgGDS splice variants promote prenylation and trafficking of GTPases containing a C-terminal polybasic region and demonstrated that SmgGDS-607 interacts with nonprenylated GTPases, whereas SmgGDS-558 interacts with prenylated GTPases in cells. The mechanism that SmgGDS-607 and SmgGDS-558 use to differentiate between prenylated and nonprenylated GTPases has not been characterized. Here, we provide evidence that SmgGDS-607 associates with GTPases through recognition of the last amino acid in the CAAX motif. We show that SmgGDS-607 forms more stable complexes in cells with nonprenylated GTPases that will become geranylgeranylated than with nonprenylated GTPases that will become farnesylated. These binding relationships similarly occur with nonprenylated SAAX mutants. Intriguingly, farnesyltransferase inhibitors increase the binding of WT K-Ras to SmgGDS-607, indicating that the pharmacological shunting of K-Ras into the geranylgeranylation pathway promotes K-Ras association with SmgGDS-607. Using recombinant proteins and prenylated peptides corresponding to the C-terminal sequences of K-Ras and Rap1B, we found that both SmgGDS-607 and SmgGDS-558 directly bind the GTPase C-terminal region, but the specificity of the SmgGDS splice variants for prenylated versus nonprenylated GTPases is diminished in vitro. Finally, we present structural homology models and data from functional prediction software to define both similar and unique features of SmgGDS-607 when compared with SmgGDS-558.

Author List

Schuld NJ, Vervacke JS, Lorimer EL, Simon NC, Hauser AD, Barbieri JT, Distefano MD, Williams CL

Authors

Joseph T. Barbieri PhD Professor in the Microbiology and Immunology department at Medical College of Wisconsin
Carol L. Williams PhD Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acid Motifs
Amino Acid Sequence
Guanine Nucleotide Exchange Factors
HEK293 Cells
Humans
Models, Chemical
Molecular Sequence Data
Monomeric GTP-Binding Proteins
Prenylation
Sequence Analysis, Protein
Software