Binding of the major phasin, PhaP1, from Ralstonia eutropha H16 to poly(3-hydroxybutyrate) granules.

The surface of polyhydroxybutyrate (PHB) storage granules in bacteria is covered mainly by proteins referred to as phasins. The layer of phasins stabilizes the granules and prevents coalescence of separated granules in the cytoplasm and nonspecific binding of other proteins to the hydrophobic surfaces of the granules. Phasin PhaP1(Reu) is the major surface protein of PHB granules in Ralstonia eutropha H16 and occurs along with three homologues (PhaP2, PhaP3, and PhaP4) that have the capacity to bind to PHB granules but are present at minor levels.