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"SP-G", a putative new surfactant protein--tissue localization and 3D structure.

Rausch F, Schicht M, Paulsen F, Ngueya I, Bräuer L, Brandt W - PLoS ONE (2012)

Bottom Line: In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G.With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level.This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany.

ABSTRACT
Surfactant proteins (SP) are well known from human lung. These proteins assist the formation of a monolayer of surface-active phospholipids at the liquid-air interface of the alveolar lining, play a major role in lowering the surface tension of interfaces, and have functions in innate and adaptive immune defense. During recent years it became obvious that SPs are also part of other tissues and fluids such as tear fluid, gingiva, saliva, the nasolacrimal system, and kidney. Recently, a putative new surfactant protein (SFTA2 or SP-G) was identified, which has no sequence or structural identity to the already know surfactant proteins. In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G. With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level. The localization of this protein in different human tissues, sequence based prediction tools for posttranslational modifications and molecular dynamic simulations reveal that SP-G has physicochemical properties similar to the already known surfactant proteins B and C. This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G. In conclusion, the results indicate SP-G as a new surfactant protein which represents an until now unknown surfactant protein class.

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Related in: MedlinePlus

Root-mean-square deviation (RMSD) plot for the SP-G backbone atoms.The RMSD was calculated over the whole simulation process to check the stability of the unmodified (black) and posttranslationally modified (red) protein structure model. Rare and small plot fluctuations indicate a stable model.
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pone-0047789-g003: Root-mean-square deviation (RMSD) plot for the SP-G backbone atoms.The RMSD was calculated over the whole simulation process to check the stability of the unmodified (black) and posttranslationally modified (red) protein structure model. Rare and small plot fluctuations indicate a stable model.

Mentions: Knowing that the overall quality of the protein model is appropriate for further studies, a 20 ns MD simulation in a water box was performed with YASARA which showed the model stability. There are no significant changes to the secondary structure visible and no hints for an unfolding of the protein structure can be observed. The results of the validation programs thereby are comparable to the aforementioned. The plot of the root-mean-square deviation (RMSD) over the simulation time as a measure for the distance between the starting and the resulting structure of the simulation also shows the stability of the 3D model (black plot, Figure 3). The RMSD reaches a plateau after about 10 ns over two clearly distinguishable phases. From this point, there are only very small fluctuations and the model can be considered as equilibrated.


"SP-G", a putative new surfactant protein--tissue localization and 3D structure.

Rausch F, Schicht M, Paulsen F, Ngueya I, Bräuer L, Brandt W - PLoS ONE (2012)

Root-mean-square deviation (RMSD) plot for the SP-G backbone atoms.The RMSD was calculated over the whole simulation process to check the stability of the unmodified (black) and posttranslationally modified (red) protein structure model. Rare and small plot fluctuations indicate a stable model.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475697&req=5

pone-0047789-g003: Root-mean-square deviation (RMSD) plot for the SP-G backbone atoms.The RMSD was calculated over the whole simulation process to check the stability of the unmodified (black) and posttranslationally modified (red) protein structure model. Rare and small plot fluctuations indicate a stable model.
Mentions: Knowing that the overall quality of the protein model is appropriate for further studies, a 20 ns MD simulation in a water box was performed with YASARA which showed the model stability. There are no significant changes to the secondary structure visible and no hints for an unfolding of the protein structure can be observed. The results of the validation programs thereby are comparable to the aforementioned. The plot of the root-mean-square deviation (RMSD) over the simulation time as a measure for the distance between the starting and the resulting structure of the simulation also shows the stability of the 3D model (black plot, Figure 3). The RMSD reaches a plateau after about 10 ns over two clearly distinguishable phases. From this point, there are only very small fluctuations and the model can be considered as equilibrated.

Bottom Line: In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G.With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level.This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Halle, Germany.

ABSTRACT
Surfactant proteins (SP) are well known from human lung. These proteins assist the formation of a monolayer of surface-active phospholipids at the liquid-air interface of the alveolar lining, play a major role in lowering the surface tension of interfaces, and have functions in innate and adaptive immune defense. During recent years it became obvious that SPs are also part of other tissues and fluids such as tear fluid, gingiva, saliva, the nasolacrimal system, and kidney. Recently, a putative new surfactant protein (SFTA2 or SP-G) was identified, which has no sequence or structural identity to the already know surfactant proteins. In this work, computational chemistry and molecular-biological methods were combined to localize and characterize SP-G. With the help of a protein structure model, specific antibodies were obtained which allowed the detection of SP-G not only on mRNA but also on protein level. The localization of this protein in different human tissues, sequence based prediction tools for posttranslational modifications and molecular dynamic simulations reveal that SP-G has physicochemical properties similar to the already known surfactant proteins B and C. This includes also the possibility of interactions with lipid systems and with that, a potential surface-regulatory feature of SP-G. In conclusion, the results indicate SP-G as a new surfactant protein which represents an until now unknown surfactant protein class.

Show MeSH
Related in: MedlinePlus