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Title: The polyomavirus BK agnoprotein co-localizes with lipid droplets

Abstract

Agnoprotein encoded by human polyomavirus BK (BKV) is a late cytoplasmic protein of 66 amino acids (aa) of unknown function. Immunofluorescence microscopy revealed a fine granular and a vesicular distribution in donut-like structures. Using BKV(Dunlop)-infected or agnoprotein-transfected cells, we investigated agnoprotein co-localization with subcellular structures. We found that agnoprotein co-localizes with lipid droplets (LD) in primary human renal tubular epithelial cells as well as in other cells supporting BKV replication in vitro (UTA, Vero cells). Using agnoprotein-enhanced green fluorescent protein (EGFP) fusion constructs, we demonstrate that agnoprotein aa 20-42 are required for targeting LD, whereas aa 1-20 or aa 42-66 were not. Agnoprotein aa 22-40 are predicted to form an amphipathic helix, and mutations A25D and F39E, disrupting its hydrophobic domain, prevented LD targeting. However, changing the phosphorylation site serine-11 to alanine or aspartic acid did not alter LD co-localization. Our findings provide new clues to unravel agnoprotein function.

Authors:
; ;  [1];  [2];  [3];  [1];  [4]
  1. Transplantation Virology, Institute for Medical Microbiology, Department of Biomedicine, University of Basel, CH-4003 Basel (Switzerland)
  2. Bio-Optics Facility, Department of Biomedicine, University of Basel, Basel (Switzerland)
  3. Department of Microbiology and Infection Control, University Hospital of North Norway, Tromso (Norway)
  4. (Switzerland)
Publication Date:
OSTI Identifier:
21357607
Resource Type:
Journal Article
Resource Relation:
Journal Name: Virology; Journal Volume: 399; Journal Issue: 2; Other Information: DOI: 10.1016/j.virol.2010.01.011; PII: S0042-6822(10)00028-0; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ALANINES; ASPARTIC ACID; DROPLETS; KIDNEYS; LIPIDS; MUTATIONS; PHOSPHORYLATION; PROTEINS; SERINE; VIRUSES; AMINO ACIDS; BODY; CARBOXYLIC ACIDS; CHEMICAL REACTIONS; HYDROXY ACIDS; MICROORGANISMS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANS; PARASITES; PARTICLES

Citation Formats

Unterstab, Gunhild, Gosert, Rainer, Leuenberger, David, Lorentz, Pascal, Rinaldo, Christine H., Hirsch, Hans H., E-mail: hans.hirsch@unibas.c, and Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel. The polyomavirus BK agnoprotein co-localizes with lipid droplets. United States: N. p., 2010. Web. doi:10.1016/j.virol.2010.01.011.
Unterstab, Gunhild, Gosert, Rainer, Leuenberger, David, Lorentz, Pascal, Rinaldo, Christine H., Hirsch, Hans H., E-mail: hans.hirsch@unibas.c, & Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel. The polyomavirus BK agnoprotein co-localizes with lipid droplets. United States. doi:10.1016/j.virol.2010.01.011.
Unterstab, Gunhild, Gosert, Rainer, Leuenberger, David, Lorentz, Pascal, Rinaldo, Christine H., Hirsch, Hans H., E-mail: hans.hirsch@unibas.c, and Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel. 2010. "The polyomavirus BK agnoprotein co-localizes with lipid droplets". United States. doi:10.1016/j.virol.2010.01.011.
@article{osti_21357607,
title = {The polyomavirus BK agnoprotein co-localizes with lipid droplets},
author = {Unterstab, Gunhild and Gosert, Rainer and Leuenberger, David and Lorentz, Pascal and Rinaldo, Christine H. and Hirsch, Hans H., E-mail: hans.hirsch@unibas.c and Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel},
abstractNote = {Agnoprotein encoded by human polyomavirus BK (BKV) is a late cytoplasmic protein of 66 amino acids (aa) of unknown function. Immunofluorescence microscopy revealed a fine granular and a vesicular distribution in donut-like structures. Using BKV(Dunlop)-infected or agnoprotein-transfected cells, we investigated agnoprotein co-localization with subcellular structures. We found that agnoprotein co-localizes with lipid droplets (LD) in primary human renal tubular epithelial cells as well as in other cells supporting BKV replication in vitro (UTA, Vero cells). Using agnoprotein-enhanced green fluorescent protein (EGFP) fusion constructs, we demonstrate that agnoprotein aa 20-42 are required for targeting LD, whereas aa 1-20 or aa 42-66 were not. Agnoprotein aa 22-40 are predicted to form an amphipathic helix, and mutations A25D and F39E, disrupting its hydrophobic domain, prevented LD targeting. However, changing the phosphorylation site serine-11 to alanine or aspartic acid did not alter LD co-localization. Our findings provide new clues to unravel agnoprotein function.},
doi = {10.1016/j.virol.2010.01.011},
journal = {Virology},
number = 2,
volume = 399,
place = {United States},
year = 2010,
month = 4
}
  • Lipid droplets are cytoplasmic organelles that store neutral lipids for membrane synthesis and energy reserves. In this study, we characterized the lipid and protein composition of purified Caenorhabditis elegans lipid droplets. These lipid droplets are composed mainly of triacylglycerols, surrounded by a phospholipid monolayer composed primarily of phosphatidylcholine and phosphatidylethanolamine. The fatty acid composition of the triacylglycerols is rich in fatty acid species obtained from the dietary Escherichia coli, including cyclopropane fatty acids and cis-vaccenic acid. Unlike other organisms, C. elegans lipid droplets contain very little cholesterol or cholesterol esters. Comparison of the lipid droplet proteomes of wild type andmore » high-fat daf-2 mutant strains shows a very similar proteome in both strains, except that the most abundant protein in the C. elegans lipid droplet proteome, MDT-28, is relatively less abundant in lipid droplets isolated from daf-2 mutants. Functional analysis of lipid droplet proteins identified in our proteomic studies indicated an enrichment of proteins required for growth and fat homeostasis in C. elegans. Finally, we confirmed the localization of one of the newly identified lipid droplet proteins, ACS-4. We found that ACS-4 localizes to the surface of lipid droplets in the C. elegans intestine and skin. This study bolsters C. elegans as a model to study the dynamics and functions of lipid droplets in a multicellular organism.« less
  • Lipid droplets are cytoplasmic organelles that store neutral lipids for membrane synthesis and energy reserves. In this study, we characterized the lipid and protein composition of purified Caenorhabditis elegans lipid droplets. These lipid droplets are composed mainly of triacylglycerols, surrounded by a phospholipid monolayer composed primarily of phosphatidylcholine and phosphatidylethanolamine. The fatty acid composition of the triacylglycerols is rich in fatty acid species obtained from the dietary Escherichia coli, including cyclopropane fatty acids and cis-vaccenic acid. Unlike other organisms, C. elegans lipid droplets contain very little cholesterol or cholesterol esters. Comparison of the lipid droplet proteomes of wild type andmore » high-fat daf-2 mutant strains shows a very similar proteome in both strains, except that the most abundant protein in the C. elegans lipid droplet proteome, MDT-28, is relatively less abundant in lipid droplets isolated from daf-2 mutants. Functional analysis of lipid droplet proteins identified in our proteomic studies indicated an enrichment of proteins required for growth and fat homeostasis in C. elegans. Finally, we confirmed the localization of one of the newly identified lipid droplet proteins, ACS-4. We found that ACS-4 localizes to the surface of lipid droplets in the C. elegans intestine and skin. This study bolsters C. elegans as a model to study the dynamics and functions of lipid droplets in a multicellular organism.« less
  • Lipid droplets are cytoplasmic organelles that store neutral lipids for membrane synthesis and energy reserves. In this study, we characterized the lipid and protein composition of purified C. elegans lipid droplets. These lipid droplets are composed mainly of triacylglycerols, surrounded by a phospholipid monolayer composed primarily of phosphatidylcholine and phosphatidylethanolamine. The fatty acid composition of the triacylglycerols was rich in fatty acid species obtained from the dietary E. coli, including cyclopropane fatty acids and cis-vaccenic acid. Unlike other organisms, C. elegans lipid droplets contain very little cholesterol or cholesterol esters. Comparison of the lipid droplet proteomes of wild type andmore » high-fat daf-2 mutant strains shows a relative decrease of MDT-28 abundance in lipid droplets isolated from daf-2 mutants. Functional analysis of lipid droplet proteins identified in our proteomic studies indicated an enrichment of proteins required for growth and fat homeostasis in C. elegans.« less
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