Characterization and identification of the proteins bound to two types of polyhydroxyalkanoate granules in Pseudomonas sp 61-3

Pseudomonas sp. 61-3 accumulates two types of polyhydroxyalkanoates (PHAs), poly(3-hydroxybutyrate) [P(3HB)], and poly(3HB-co-3-hydroxyalkanoates) [P(3HB-co-3HA)], and some proteins associated with their PHA granules have been identified. To date, PhaF(Ps) (GA36) and PhaI(Ps) (GA18) were identified from P(3HB-co-3HA) granules. In this study, the gene encoding GA24 associated with P(3HB) granule was identified as phbP(Ps). PhbP(Ps) was composed of 192 amino acids with a calculated molecular mass of 20.4kDa and was assumed to be a phasin. phbF(Ps) gene and unknown ORF were also found on phb locus. PhbF(Ps) was anticipated to be the transcriptional repressor of phbP(Ps) gene. PhbP(Ps) was bound to the P(3HB-co-3HA) granules with 3HB composition of more than 87mol%, and PhaI(Ps) and PhaF(Ps) were bound to the P(3HB-co-3HA) granules with 3HA (C-6-C-12) composition of more than 13mol% in the producing cells, suggesting that localization of these proteins is attributed to the monomer compositions of the copolymers.