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A phasin with many faces: structural insights on PhaP from Azotobacter sp. FA8.

Mezzina MP, Wetzler DE, Catone MV, Bucci H, Di Paola M, Pettinari MJ - PLoS ONE (2014)

Bottom Line: Phasins are a group of proteins associated to granules of polyhydroxyalkanoates (PHAs).Several experimental data support that it is a tetramer, probably due to interactions between coiled-coil regions.These structural features have also been detected in other phasins, and may be related to their functional diversity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.

ABSTRACT
Phasins are a group of proteins associated to granules of polyhydroxyalkanoates (PHAs). Apart from their structural role as part of the PHA granule cover, different structural and regulatory functions have been found associated to many of them, and several biotechnological applications have been developed using phasin protein fusions. Despite their remarkable functional diversity, the structure of these proteins has not been analyzed except in very few studies. PhaP from Azotobacter sp. FA8 (PhaPAz) is a representative of the prevailing type in the multifunctional phasin protein family. Previous work performed in our laboratory using this protein have demonstrated that it has some very peculiar characteristics, such as its stress protecting effects in recombinant Escherichia coli, both in the presence and absence of PHA. The aim of the present work was to perform a structural characterization of this protein, to shed light on its properties. Its aminoacid composition revealed that it lacks clear hydrophobic domains, a characteristic that appears to be common to most phasins, despite their lipid granule binding capacity. The secondary structure of this protein, consisting of α-helices and disordered regions, has a remarkable capacity to change according to its environment. Several experimental data support that it is a tetramer, probably due to interactions between coiled-coil regions. These structural features have also been detected in other phasins, and may be related to their functional diversity.

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PhaPAz Helical Wheel Diagram.The representation was performed using Pepwheel (http://emboss.bioinformatics.nl/cgi-bin/emboss/pepwheel) that detects potencial amphipathic helices. Residues ACFGILMVWY (polar) are marked as blue squares and all other residues are unmarked.
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pone-0103012-g002: PhaPAz Helical Wheel Diagram.The representation was performed using Pepwheel (http://emboss.bioinformatics.nl/cgi-bin/emboss/pepwheel) that detects potencial amphipathic helices. Residues ACFGILMVWY (polar) are marked as blue squares and all other residues are unmarked.

Mentions: To further investigate if these predicted helices have amphipathic characteristics that could explain the interactions of PhaPAz with PHA granules, we represented these helices using Pepwheel (http://emboss.bioinformatics.nl/cgi-bin/emboss/pepwheel). (Fig. 2). This representation showed that the first helix (L6 to L57) and the fourth one (E131 to A177) seem to have clearly defined polar and non-polar sides. These amphipathic helices could be involved in the simultaneous interaction of phasins with PHA and an aqueous environment, and also in protein-protein interactions.


A phasin with many faces: structural insights on PhaP from Azotobacter sp. FA8.

Mezzina MP, Wetzler DE, Catone MV, Bucci H, Di Paola M, Pettinari MJ - PLoS ONE (2014)

PhaPAz Helical Wheel Diagram.The representation was performed using Pepwheel (http://emboss.bioinformatics.nl/cgi-bin/emboss/pepwheel) that detects potencial amphipathic helices. Residues ACFGILMVWY (polar) are marked as blue squares and all other residues are unmarked.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4117528&req=5

pone-0103012-g002: PhaPAz Helical Wheel Diagram.The representation was performed using Pepwheel (http://emboss.bioinformatics.nl/cgi-bin/emboss/pepwheel) that detects potencial amphipathic helices. Residues ACFGILMVWY (polar) are marked as blue squares and all other residues are unmarked.
Mentions: To further investigate if these predicted helices have amphipathic characteristics that could explain the interactions of PhaPAz with PHA granules, we represented these helices using Pepwheel (http://emboss.bioinformatics.nl/cgi-bin/emboss/pepwheel). (Fig. 2). This representation showed that the first helix (L6 to L57) and the fourth one (E131 to A177) seem to have clearly defined polar and non-polar sides. These amphipathic helices could be involved in the simultaneous interaction of phasins with PHA and an aqueous environment, and also in protein-protein interactions.

Bottom Line: Phasins are a group of proteins associated to granules of polyhydroxyalkanoates (PHAs).Several experimental data support that it is a tetramer, probably due to interactions between coiled-coil regions.These structural features have also been detected in other phasins, and may be related to their functional diversity.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, IQUIBICEN-CONICET, Buenos Aires, Argentina.

ABSTRACT
Phasins are a group of proteins associated to granules of polyhydroxyalkanoates (PHAs). Apart from their structural role as part of the PHA granule cover, different structural and regulatory functions have been found associated to many of them, and several biotechnological applications have been developed using phasin protein fusions. Despite their remarkable functional diversity, the structure of these proteins has not been analyzed except in very few studies. PhaP from Azotobacter sp. FA8 (PhaPAz) is a representative of the prevailing type in the multifunctional phasin protein family. Previous work performed in our laboratory using this protein have demonstrated that it has some very peculiar characteristics, such as its stress protecting effects in recombinant Escherichia coli, both in the presence and absence of PHA. The aim of the present work was to perform a structural characterization of this protein, to shed light on its properties. Its aminoacid composition revealed that it lacks clear hydrophobic domains, a characteristic that appears to be common to most phasins, despite their lipid granule binding capacity. The secondary structure of this protein, consisting of α-helices and disordered regions, has a remarkable capacity to change according to its environment. Several experimental data support that it is a tetramer, probably due to interactions between coiled-coil regions. These structural features have also been detected in other phasins, and may be related to their functional diversity.

Show MeSH
Related in: MedlinePlus