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Schuld NJ, Vervacke JS, Lorimer EL, Simon NC, Hauser AD, Barbieri JT, Distefano MD, Williams CL. 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; 289:6862-6876. [PMID: 24415755 PMCID: PMC3945348 DOI: 10.1074/jbc.m113.527192] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/09/2014] [Indexed: 12/31/2022] Open
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.
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Affiliation(s)
- Nathan J Schuld
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Jeffrey S Vervacke
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55414
| | - Ellen L Lorimer
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Nathan C Simon
- Department of Microbiology, Immunology, and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Andrew D Hauser
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Joseph T Barbieri
- Department of Microbiology, Immunology, and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Mark D Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55414
| | - Carol L Williams
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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Corech R, Rao A, Laxova A, Moss J, Rock MJ, Li Z, Kosorok MR, Splaingard ML, Farrell PM, Barbieri JT. Early immune response to the components of the type III system of Pseudomonas aeruginosa in children with cystic fibrosis. J Clin Microbiol 2005; 43:3956-62. [PMID: 16081936 PMCID: PMC1233990 DOI: 10.1128/jcm.43.8.3956-3962.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Revised: 01/05/2005] [Accepted: 04/13/2005] [Indexed: 11/20/2022] Open
Abstract
The lungs of patients with cystic fibrosis (CF) are colonized initially by Pseudomonas aeruginosa, which is associated with progressive lung destruction and increased mortality. The pathogenicity of P. aeruginosa is caused by a number of virulence factors, including exotoxin A (ETA) and the type III cytotoxins (ExoS, ExoT, ExoU, and ExoY). P. aeruginosa contacts the plasma membrane to deliver type III cytotoxins through a channel formed by PopB, PopD, and PcrV; ETA enters mammalian cells via receptor-mediated endocytosis. The Wisconsin CF Neonatal Screening Project is a longitudinal investigation to assess the potential benefits and risks of newborn screening for CF; the project was the source of serum samples used in this study. Past studies evaluated the longitudinal appearance of antibodies to ETA and elastase and P. aeruginosa infections in patients with CF. The current study characterized the longitudinal appearance of antibodies to components of the type III system in children with CF. Western blot analyses showed that serum antibodies to PopB, PcrV, and ExoS were common. Longitudinal enzyme-linked immunosorbent assays determined that the first detection of antibodies to pooled ExoS/PopB occurred at a time similar to those of detection of antibodies to a P. aeruginosa cell lysate and the identification of oropharyngeal cultures positive for P. aeruginosa. This indicates that children with CF are colonized early with P. aeruginosa expressing the type III system, implicating it in early pathogenesis, and implies that surveillance of clinical symptoms, oropharyngeal cultures, and seroconversion to type III antigens may facilitate early detection of P. aeruginosa infections.
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Affiliation(s)
- R. Corech
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - A. Rao
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - A. Laxova
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - J. Moss
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - M. J. Rock
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - Z. Li
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - M. R. Kosorok
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - M. L. Splaingard
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - P. M. Farrell
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
| | - J. T. Barbieri
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin, Department of Pediatrics, University of Wisconsin Medical School, Madison, Wisconsin, Pulmonary Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, Department of Biostatistics and Medical Informatics, University of Wisconsin Medical School, Madison, Wisconsin
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