liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
Evolutionary History of the Non-Specific Lipid Transfer Proteins
Linköping University, Department of Physics, Chemistry and Biology, Molecular genetics. Linköping University, The Institute of Technology.
Abo Akad University.
Abo Akad University.
Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular genetics.
2011 (English)In: MOLECULAR PLANT, ISSN 1674-2052, Vol. 4, no 6, 947-964 p.Article in journal (Refereed) Published
Abstract [en]

The non-specific lipid transfer proteins (nsLTPs) are small, basic proteins characterized by a tunnel-like hydrophobic cavity, capable of transferring various lipid molecules between lipid bilayers. Most nsLTPs are synthesized with an N-terminal signal peptide that localizes the protein to the apoplastic space. The nsLTPs have only been identified in seed plants, where they are encoded by large gene families. We have initiated an analysis of the evolutionary history of the nsLTP family using genomic and EST information from non-seed land plants and green algae to determine: (1) when the nsLTP family arose, (2) how often new nsLTP subfamilies have been created, and (3) how subfamilies differ in their patterns of expansion and loss in different plant lineages. In this study, we searched sequence databases and found that genes and transcripts encoding nsLTPs are abundant in liverworts, mosses, and all other investigated land plants, but not present in any algae. The tertiary structures of representative liverwort and moss nsLTPs were further studied with homology modeling. The results indicate that the nsLTP family has evolved after plants conquered land. Only two of the four major subfamilies of nsLTPs found in flowering plants are present in mosses and liverworts. The additional subfamilies have arisen later, during land plant evolution. In this report, we also introduce a modified nsLTP classification system.

Place, publisher, year, edition, pages
Oxford University Press (OUP): Policy B / Oxford University Press (OUP) , 2011. Vol. 4, no 6, 947-964 p.
Keyword [en]
Lipids; evolutionary genetics; molecular biology; molecular evolution; bryophytes; ferns
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-73738DOI: 10.1093/mp/ssr019ISI: 000297377100003OAI: diva2:476391
Available from: 2012-01-12 Created: 2012-01-12 Last updated: 2013-09-30
In thesis
1. Plant lipid transfer proteins: Evolution, expression and function
Open this publication in new window or tab >>Plant lipid transfer proteins: Evolution, expression and function
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The plant non-specific lipid transfer proteins (nsLTPs) are known for the ability to transfer different lipids in vitro, but their in vivo functions have not yet been elucidated. They seem to play a role in the defense against biotic and abiotic stresses; the gene expression of nsLTPs is often upregulated when exposed to stresses. Further, two different nsLTPs have been shown to affect the lipid composition of the plant cuticle, a structure acting as a protective barrier. However, more evidence is needed to prove this hypothesis and to pinpoint their exact role in this process.

In this thesis I have shown that the nsLTPs are found in all land plants, but not in any of the studied algae. This supports a role in defense response, since protection against dehydration, radiation, pathogens and other stresses played a crucial role when plants adapted to a life on land. Characterization of the nsLTPs in early diverging land plant revealed that even though the amino acid similarity towards nsLTPs in flowering plants is not very high, the main properties of the proteins are still the same (Paper I). This includes the protein structure, which consists of α-helices surrounding a lipid binding cavity, a conserved pattern of cysteine residues involved in disulphide bonds and a signal sequence directing the protein to the  extracellular space. Further, the expression of nsLTPs in the moss Physcomitrella patens was shown to respond to stresses, and construction of an YFP-LTP fusion protein confirmed the localization to the periphery of the cell in planta (Paper II). Heterologous expressed Physcomitrella nsLTPs were also shown to have the ability to bind lipids and to be very heat stable, features previously only studied in nsLTPs from flowering plants. By examining the presence of a cuticle in Physcomitrella, a correlation between the nsLTPs´ lipid binding ability and the lipid composition of the cuticle could be found, which further strengthens the involvement of nsLTPs in transfer of lipids for cuticle construction.

In the flowering plant Arabidopsis thaliana, I showed that several of the nsLTPs followed the same expression pattern when examining data from different tissues, stress treatments, hormones, chemical treatments and developmental stages, but also that four of the genes were undergoing alternative splicing resulting in different isoforms of the proteins (Paper III). Based on their expression patterns, the genes could be divided into three different coexpression networks. By examining other genes similarly expressed, each network could be designated to a putative function: Transfer of lipids for synthesis of the cuticle, suberin layer and sporopollenin, respectively. In Paper IV, these hypotheses were tested in vivo by examining knockout mutants of several nsLTPs in Arabidopsis. The involvement in sporopollenin deposition could be confirmed; two of the knockout lines showed collapsed pollen grains. Further, two other lines showed an increased seed coat permeability due to an altered lipid composition of the suberin layer. Together, the results support a role for nsLTPs in construction of the protecting barriers in all land plants.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. 56 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1525
National Category
Natural Sciences
urn:nbn:se:liu:diva-98117 (URN)10.3384/diss.diva-98117 (DOI)978-91-7519-578-0 (print) (ISBN)
Public defence
2013-10-22, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:00 (English)
Available from: 2013-09-30 Created: 2013-09-30 Last updated: 2013-09-30Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Edqvist, Johan
By organisation
Molecular geneticsThe Institute of Technology
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 52 hits
ReferencesLink to record
Permanent link

Direct link