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An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein

BACKGROUND: Profilins are critical to cytoskeletal dynamics in eukaryotes; however, little is known about their viral counterparts. In this study, a poxviral profilin homolog, ectromelia virus strain Moscow gene 141 (ECTV-PH), was investigated by a variety of experimental and bioinformatics techniqu...

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Autores principales: Butler-Cole, Christine, Wagner, Mary J, Da Silva, Melissa, Brown, Gordon D, Burke, Robert D, Upton, Chris
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1964790/
https://www.ncbi.nlm.nih.gov/pubmed/17650322
http://dx.doi.org/10.1186/1743-422X-4-76
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author Butler-Cole, Christine
Wagner, Mary J
Da Silva, Melissa
Brown, Gordon D
Burke, Robert D
Upton, Chris
author_facet Butler-Cole, Christine
Wagner, Mary J
Da Silva, Melissa
Brown, Gordon D
Burke, Robert D
Upton, Chris
author_sort Butler-Cole, Christine
collection PubMed
description BACKGROUND: Profilins are critical to cytoskeletal dynamics in eukaryotes; however, little is known about their viral counterparts. In this study, a poxviral profilin homolog, ectromelia virus strain Moscow gene 141 (ECTV-PH), was investigated by a variety of experimental and bioinformatics techniques to characterize its interactions with cellular and viral proteins. RESULTS: Profilin-like proteins are encoded by all orthopoxviruses sequenced to date, and share over 90% amino acid (aa) identity. Sequence comparisons show highest similarity to mammalian type 1 profilins; however, a conserved 3 aa deletion in mammalian type 3 and poxviral profilins suggests that these homologs may be more closely related. Structural analysis shows that ECTV-PH can be successfully modelled onto both the profilin 1 crystal structure and profilin 3 homology model, though few of the surface residues thought to be required for binding actin, poly(L-proline), and PIP(2 )are conserved. Immunoprecipitation and mass spectrometry identified two proteins that interact with ECTV-PH within infected cells: alpha-tropomyosin, a 38 kDa cellular actin-binding protein, and the 84 kDa product of vaccinia virus strain Western Reserve (VACV-WR) 148, which is the truncated VACV counterpart of the orthopoxvirus A-type inclusion (ATI) protein. Western and far-western blots demonstrated that the interaction with alpha-tropomyosin is direct, and immunofluorescence experiments suggest that ECTV-PH and alpha-tropomyosin may colocalize to structures that resemble actin tails and cellular protrusions. Sequence comparisons of the poxviral ATI proteins show that although full-length orthologs are only present in cowpox and ectromelia viruses, an ~ 700 aa truncated ATI protein is conserved in over 90% of sequenced orthopoxviruses. Immunofluorescence studies indicate that ECTV-PH localizes to cytoplasmic inclusion bodies formed by both truncated and full-length versions of the viral ATI protein. Furthermore, colocalization of ECTV-PH and truncated ATI protein to protrusions from the cell surface was observed. CONCLUSION: These results suggest a role for ECTV-PH in intracellular transport of viral proteins or intercellular spread of the virus. Broader implications include better understanding of the virus-host relationship and mechanisms by which cells organize and control the actin cytoskeleton.
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spelling pubmed-19647902007-09-06 An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein Butler-Cole, Christine Wagner, Mary J Da Silva, Melissa Brown, Gordon D Burke, Robert D Upton, Chris Virol J Research BACKGROUND: Profilins are critical to cytoskeletal dynamics in eukaryotes; however, little is known about their viral counterparts. In this study, a poxviral profilin homolog, ectromelia virus strain Moscow gene 141 (ECTV-PH), was investigated by a variety of experimental and bioinformatics techniques to characterize its interactions with cellular and viral proteins. RESULTS: Profilin-like proteins are encoded by all orthopoxviruses sequenced to date, and share over 90% amino acid (aa) identity. Sequence comparisons show highest similarity to mammalian type 1 profilins; however, a conserved 3 aa deletion in mammalian type 3 and poxviral profilins suggests that these homologs may be more closely related. Structural analysis shows that ECTV-PH can be successfully modelled onto both the profilin 1 crystal structure and profilin 3 homology model, though few of the surface residues thought to be required for binding actin, poly(L-proline), and PIP(2 )are conserved. Immunoprecipitation and mass spectrometry identified two proteins that interact with ECTV-PH within infected cells: alpha-tropomyosin, a 38 kDa cellular actin-binding protein, and the 84 kDa product of vaccinia virus strain Western Reserve (VACV-WR) 148, which is the truncated VACV counterpart of the orthopoxvirus A-type inclusion (ATI) protein. Western and far-western blots demonstrated that the interaction with alpha-tropomyosin is direct, and immunofluorescence experiments suggest that ECTV-PH and alpha-tropomyosin may colocalize to structures that resemble actin tails and cellular protrusions. Sequence comparisons of the poxviral ATI proteins show that although full-length orthologs are only present in cowpox and ectromelia viruses, an ~ 700 aa truncated ATI protein is conserved in over 90% of sequenced orthopoxviruses. Immunofluorescence studies indicate that ECTV-PH localizes to cytoplasmic inclusion bodies formed by both truncated and full-length versions of the viral ATI protein. Furthermore, colocalization of ECTV-PH and truncated ATI protein to protrusions from the cell surface was observed. CONCLUSION: These results suggest a role for ECTV-PH in intracellular transport of viral proteins or intercellular spread of the virus. Broader implications include better understanding of the virus-host relationship and mechanisms by which cells organize and control the actin cytoskeleton. BioMed Central 2007-07-24 /pmc/articles/PMC1964790/ /pubmed/17650322 http://dx.doi.org/10.1186/1743-422X-4-76 Text en Copyright © 2007 Butler-Cole et al; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( (http://creativecommons.org/licenses/by/2.0) ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Research
Butler-Cole, Christine
Wagner, Mary J
Da Silva, Melissa
Brown, Gordon D
Burke, Robert D
Upton, Chris
An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein
title An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein
title_full An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein
title_fullStr An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein
title_full_unstemmed An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein
title_short An ectromelia virus profilin homolog interacts with cellular tropomyosin and viral A-type inclusion protein
title_sort ectromelia virus profilin homolog interacts with cellular tropomyosin and viral a-type inclusion protein
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1964790/
https://www.ncbi.nlm.nih.gov/pubmed/17650322
http://dx.doi.org/10.1186/1743-422X-4-76
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