Identification of a 13-kDa protein associated with the polyhydroxyalkanoic acid granules from Acinetobacter spp.

Proteins associated with poly-beta-hydroxybutyrate (PHB) granules were purified from four Acinetobacter strains isolated from modified activated sludge treatment plants. Four predominant proteins of 64 kDa, 41 kDa, 38 kDa and 13 kDa were identified. N-terminal amino acid sequencing of the 64-kDa and 13-kDa proteins from Acinetobacter RA3849 identified these proteins as the products of the phaCAc and phaPAc (formerly designated ORF1) genes, respectively. The expression of the 13-kDa protein (referred to as GA13) is shown to be required for the accumulation of large amounts of PHB in a recombinant Escherichia coli strain.