Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity

HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells) is the first member in a new family of protein-lipid complexes with broad tumoricidal activity. Elucidating the molecular structure and the domains crucial for HAMLET formation is fundamental for understanding its tumoricidal function. Here...

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Main Authors: Ho, James C. S., Rydstrom, Anna, Manimekalai, Malathy Sony Subramanian, Svanborg, Catharina, Grüber, Gerhard
Other Authors: School of Biological Sciences
Format: Article
Language:English
Published: 2013
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Online Access:https://hdl.handle.net/10356/98357
http://hdl.handle.net/10220/10905
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-983572023-02-28T17:04:34Z Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity Ho, James C. S. Rydstrom, Anna Manimekalai, Malathy Sony Subramanian Svanborg, Catharina Grüber, Gerhard School of Biological Sciences DRNTU::Science::Biological sciences HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells) is the first member in a new family of protein-lipid complexes with broad tumoricidal activity. Elucidating the molecular structure and the domains crucial for HAMLET formation is fundamental for understanding its tumoricidal function. Here we present the low-resolution solution structure of the complex of oleic acid bound HAMLET, derived from small angle X-ray scattering data. HAMLET shows a two-domain conformation with a large globular domain and an extended part of about 2.22 nm in length and 1.29 nm width. The structure has been superimposed into the related crystallographic structure of human α-lactalbumin, revealing that the major part of α-lactalbumin accommodates well in the shape of HAMLET. However, the C-terminal residues from L105 to L123 of the crystal structure of the human α-lactalbumin do not fit well into the HAMLET structure, resulting in an extended conformation in HAMLET, proposed to be required to form the tumoricidal active HAMLET complex with oleic acid. Consistent with this low resolution structure, we identified biologically active peptide epitopes in the globular as well as the extended domains of HAMLET. Peptides covering the alpha1 and alpha2 domains of the protein triggered rapid ion fluxes in the presence of sodium oleate and were internalized by tumor cells, causing rapid and sustained changes in cell morphology. The alpha peptide-oleate bound forms also triggered tumor cell death with comparable efficiency as HAMLET. In addition, shorter peptides corresponding to those domains are biologically active. These findings provide novel insights into the structural prerequisites for the dramatic effects of HAMLET on tumor cells. Published version 2013-07-03T03:15:34Z 2019-12-06T19:54:02Z 2013-07-03T03:15:34Z 2019-12-06T19:54:02Z 2012 2012 Journal Article Ho, J. C. S., Rydstrom, A., Manimekalai, M. S. S., Svanborg, C., & Grüber, G. (2012). Low Resolution Solution Structure of HAMLET and the Importance of Its Alpha-Domains in Tumoricidal Activity. PLoS ONE, 7(12), e53051. 1932-6203 https://hdl.handle.net/10356/98357 http://hdl.handle.net/10220/10905 10.1371/journal.pone.0053051 23300861 en PLoS ONE © 2012 The Authors. This paper was published in PLoS ONE and is made available as an electronic reprint (preprint) with permission of The Authors. The paper can be found at the following official DOI: [http://dx.doi.org/10.1371/journal.pone.0053051]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Science::Biological sciences
spellingShingle DRNTU::Science::Biological sciences
Ho, James C. S.
Rydstrom, Anna
Manimekalai, Malathy Sony Subramanian
Svanborg, Catharina
Grüber, Gerhard
Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity
description HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells) is the first member in a new family of protein-lipid complexes with broad tumoricidal activity. Elucidating the molecular structure and the domains crucial for HAMLET formation is fundamental for understanding its tumoricidal function. Here we present the low-resolution solution structure of the complex of oleic acid bound HAMLET, derived from small angle X-ray scattering data. HAMLET shows a two-domain conformation with a large globular domain and an extended part of about 2.22 nm in length and 1.29 nm width. The structure has been superimposed into the related crystallographic structure of human α-lactalbumin, revealing that the major part of α-lactalbumin accommodates well in the shape of HAMLET. However, the C-terminal residues from L105 to L123 of the crystal structure of the human α-lactalbumin do not fit well into the HAMLET structure, resulting in an extended conformation in HAMLET, proposed to be required to form the tumoricidal active HAMLET complex with oleic acid. Consistent with this low resolution structure, we identified biologically active peptide epitopes in the globular as well as the extended domains of HAMLET. Peptides covering the alpha1 and alpha2 domains of the protein triggered rapid ion fluxes in the presence of sodium oleate and were internalized by tumor cells, causing rapid and sustained changes in cell morphology. The alpha peptide-oleate bound forms also triggered tumor cell death with comparable efficiency as HAMLET. In addition, shorter peptides corresponding to those domains are biologically active. These findings provide novel insights into the structural prerequisites for the dramatic effects of HAMLET on tumor cells.
author2 School of Biological Sciences
author_facet School of Biological Sciences
Ho, James C. S.
Rydstrom, Anna
Manimekalai, Malathy Sony Subramanian
Svanborg, Catharina
Grüber, Gerhard
format Article
author Ho, James C. S.
Rydstrom, Anna
Manimekalai, Malathy Sony Subramanian
Svanborg, Catharina
Grüber, Gerhard
author_sort Ho, James C. S.
title Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity
title_short Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity
title_full Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity
title_fullStr Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity
title_full_unstemmed Low resolution solution structure of HAMLET and the importance of its alpha-domains in tumoricidal activity
title_sort low resolution solution structure of hamlet and the importance of its alpha-domains in tumoricidal activity
publishDate 2013
url https://hdl.handle.net/10356/98357
http://hdl.handle.net/10220/10905
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