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

Abstract

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, PhaFPs (GA36) and PhaIPs (GA18) were identified from P(3HB-co-3HA) granules. In this study, the gene encoding GA24 associated with P(3HB) granule was identified as phbPPs. PhbPPs was composed of 192 amino acids with a calculated molecular mass of 20.4 kDa and was assumed to be a phasin. phbFPs gene and unknown ORF were also found on phb locus. PhbFPs was anticipated to be the transcriptional repressor of phbPPs gene. PhbPPs was bound to the P(3HB-co-3HA) granules with 3HB composition of more than 87 mol%, and PhaIPs and PhaFPs were bound to the P(3HB-co-3HA) granules with 3HA (C6-C12) composition of more than 13 mol% in the producing cells, suggesting that localization of these proteins is attributed to the monomer compositions of the copolymers.

Transcriptional profiling of threePseudomonas syringaepv.actinidiaebiovars reveals different responses to apoplast-like conditions related to strain virulence

“…We also observed the strong common induction of a MaoC-like hydratase (MaoC), an (R)-hydratase that links β-oxidation to the PHA biosynthesis pathways (38)(39)(40)(41). PHAs provide intracellular carbon and energy reserves under nutrient-limited conditions with excess carbon (37), so this pathway may provide a common adaptive response allowing P. syringae to overcome nutrient limitation within the apoplast.…”

“…The modulated genes included those encoding sigma factors (which control the transcription of broad sets of target genes) and proteins related to phosphate starvation, including a PhoH-like protein, the transcriptional regulator PhoP, the phosphate starvation-inducible protein PsiF, and the phosphonate metabolism protein PhnM. Phosphate limitation has a pleiotropic effect on bacterial physiology, triggering the degradation of polyphosphate, the accumulation of phosphate-free membrane lipids, and the accumulation of polyhydroxyalkanoate (PHA) in regulatory granules (36,37). The Psa biovars and Pto induced two main genes related to PHA synthesis, encoding the phasins PhaI and PhaF.…”

Phasins, Multifaceted Polyhydroxyalkanoate Granule-Associated Proteins

“…A recent study that characterized granules containing different polymer compositions in Pseudomonas sp. 61-3 determined that phasins PhaF and PhaI, which have the Phasin domain (Table 1), were found on the surface of PHAmcl granules while PhbP, which belongs to the largest phasin family (PF09361) containing the Phasin_2 domain, was bound to PHB granules in this organism (14), suggesting that phasins have a certain degree of specificity. The ability of Pseudomonas strains to accumulate PHB could have been acquired by horizontal gene transfer (15,16), so it is possible that genes encoding the PHBrelated phasins in these bacteria could have also been acquired in this manner.…”

“…accumulate only PHAmcl, several strains, such as Pseudomonas sp. 61-3 (14), P. extremaustralis (15), and P. pseudoalcaligenes (16), have been observed to accumulate both PHAmcl and PHB. These bacteria contain separate biosynthesis gene clusters for each polymer and different phasins that belong to different phasin families.…”

Footprint area analysis of binary imaged Cupriavidus necator cells to study PHB production at balanced, transient, and limited growth conditions in a cascade process

“…In this context, PHA synthase activity is triggered by external factors such as pH value, temperature, or substrate concentration; this activity determines molar masses (Rehm and Steinbüchel 1999) and even defines the intracellular granule location (Sudesh et al 2002). Particularities of the microbial production strain additionally impact PHA granule formation and granule structure (Hauf et al 2015; Hokamura et al 2015; Zinn et al 2001). From the technological point of view, larger PHA granules facilitate PHA recovery grace to their rather low density (Wang et al 2014).…”