Heterologous complementation of the exopolysaccharide synthesis and carbon utilization phenotypes of<i>Sinorhizobium meliloti</i>Rm1021 polyhydroxyalkanoate synthesis mutants

Aneja, Punita; Dai, Meixue; Lacorre, Delphine A.; Pillon, Brent; Charles, Trevor C.

doi:10.1016/j.femsle.2004.08.045

Cited by 39 publications

(35 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Since the double mutant produced a significantly larger amount of glycogen than that produced by the phbC mutant in YMB medium (Table 2), we assume that the inclusion in the double mutant could be glycogen. However, the carbon flow, especially a correlation between PHB and glycogen in rhizobia, is far from clear (1,9,27,38,39). We are pursuing further studies to clarify the role of phasins in regulating storage polymer synthesis and carbon metabolism in S. meliloti.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of the Poly-3-Hydroxybutyrate (PHB) Granule-Associated Proteins (PhaP1 and PhaP2) on PHB Accumulation and Symbiotic Nitrogen Fixation in Sinorhizobium meliloti Rm1021

et al. 2007

Self Cite

View full text Add to dashboard Cite

Sinorhizobium meliloti cells store excess carbon as intracellular poly-3-hydroxybutyrate (PHB) granules that assist survival under fluctuating nutritional conditions. PHB granule-associated proteins (phasins) are proposed to regulate PHB synthesis and granule formation. Although the enzymology and genetics of PHB metabolism in S. meliloti have been well characterized, phasins have not yet been described for this organism. Comparison of the protein profiles of the wild type and a PHB synthesis mutant revealed two major proteins absent from the mutant. These were identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) as being encoded by the SMc00777 (phaP1) and SMc02111 (phaP2) genes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins associated with PHB granules followed by MALDI-TOF confirmed that PhaP1 and PhaP2 were the two major phasins. Double mutants were defective in PHB production, while single mutants still produced PHB, and unlike PHB synthesis mutants that have reduced exopolysaccharide, the double mutants had higher exopolysaccharide levels. Medicago truncatula plants inoculated with the double mutant exhibited reduced shoot dry weight (SDW), although there was no corresponding reduction in nitrogen fixation activity. Whether the phasins are involved in a metabolic regulatory response or whether the reduced SDW is due to a reduction in assimilation of fixed nitrogen rather than a reduction in nitrogen fixation activity remains to be established.The alfalfa root nodule symbiont Sinorhizobium meliloti stores excess carbon as intracellular poly-3-hydroxybutyrate (PHB) granules as its main carbon storage compound. Mutant analysis has demonstrated that PHB metabolism plays a role in rhizobium-legume symbiosis (19,38,39,43), although the metabolic role of the PHB cycle during nitrogen fixation is still not completely understood (28). While the enzymology and genetics of PHB biosynthesis have been studied extensively with various bacteria (35), less is known about the regulation of this process in S. meliloti. So far, the following two major types of PHB accumulation effectors have been investigated in several bacteria: (i) the granule-associated proteins, or phasins, encoded by phaP genes, which bind to PHB granules and promote PHB synthesis; and (ii) a regulator, encoded by phaR (15). PhaR was first designated AniA in rhizobia because of its expression under anaerobic growth conditions (27). Although the function of aniA has still to be clarified, Povolo and Casella provided evidence that AniA, in partitioning carbon flow in cells, affects not only PHB production but also the production of extracellularly polymeric substances and nitrogen fixation in S. meliloti Rm41 (27). In Rhizobium etli, this protein has been proposed to be involved in directing carbon flow (8, 9). Phasins have not yet been described for rhizobia.Phasins are characterized by low molecular masses (mostly between 11 and 25 kDa), have an amphiphilic character and a high affinity for polyhyd...

show abstract

Section: Discussionmentioning

confidence: 99%

“…An intriguing result was the increase in EPS synthesis in the phaP mutants under growth conditions that yield reduced levels of EPS synthesis in other PHB synthesis mutants (1). Whether this increased EPS is succinoglycan, galactoglucan, or some other EPS is not known at this point.…”

Section: Discussionmentioning

confidence: 99%

Influence of the Poly-3-Hydroxybutyrate (PHB) Granule-Associated Proteins (PhaP1 and PhaP2) on PHB Accumulation and Symbiotic Nitrogen Fixation in Sinorhizobium meliloti Rm1021

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…39) phbB mutants have also been reported for poor growth and less PHB accumulation in many bacteria, suggesting its usefulness during PHB synthesis process. 40) Additionally, many previous studies have amplified phbB gene in the isolates to deduce the molecular nature of PHB production in them. 41,42) Thus, in order to confirm the role of phbB gene of phb operon during pathway of PHB synthesis, amplification of phbB gene was carried out in the isolates.…”

Section: Discussionmentioning

confidence: 99%

Production, optimization and characterization of polyhydroxybutyrate, a biodegradable plastic by Bacillus spp.

Bhagowati

Pradhan

Dash

et al. 2015

Bioscience, Biotechnology, and Biochemistry

View full text Add to dashboard Cite

Poly-β-hydroxybutyrate (PHB) is the intracellular lipid reserve accumulated by many bacteria. The most potent terrestrial bacterium Bacillus cereus SE-1 showed more PHB accumulating cells (22.1 and 40% after 48 and 72 h) than that of the marine Bacillus sp. CS-605 (5 and 33% after 48 and 72 h). Both the isolates harbored phbB gene and the characteristics C=O peak was observed in the extracted PHB by Fourier transformed infrared spectroscopy analysis. Maltose was found to be the most suitable carbon source for the accumulation of PHB in B. cereus SE-1. The extracted PHB sample from B. cereus SE-1 was blended with a thermoplastic starch (TS) and an increased thermoplasticity and decreased crystallinity were observed after blending in comparison to the standard PHB. The melting temperature (Tm), melting enthalpy (∆Hf), and crystallinity (Xc) of the blended PHB sample were found to be 109.4 °C, 64.58 J/g, and 44.23%, respectively.

show abstract

“…However, more recent proteomic and transcriptomic studies have indicated that both phaC1 and phaC2 are present in nodule bacteroids (13,14). In a different study, Aneja and coworkers attempted to complement a phaC-defective Ensifer (formerly Sinorhizobium) meliloti mutant with a B. japonicum cosmid library in order to isolate genes encoding functional PHA synthases in this rhizobial species and were successful only with phaC1 (15).…”

mentioning

confidence: 99%

Analysis of Two Polyhydroxyalkanoate Synthases in Bradyrhizobium japonicum USDA 110

Quelas

Mongiardini

Pérez-Giménez

et al. 2013

Journal of Bacteriology

View full text Add to dashboard Cite

bBradyrhizobium japonicum USDA 110 has five polyhydroxyalkanoate (PHA) synthases (PhaC) annotated in its genome: bll4360 (phaC1), bll6073 (phaC2), blr3732 (phaC3), blr2885 (phaC4), and bll4548 (phaC5). All these proteins possess the catalytic triad and conserved amino acid residues of polyester synthases and are distributed into four different PhaC classes. We obtained mutants in each of these paralogs and analyzed phaC gene expression and PHA production in liquid cultures. Despite the genetic redundancy, only phaC1 and phaC2 were expressed at significant rates, while PHA accumulation in stationary-phase cultures was impaired only in the ⌬phaC1 mutant. Meanwhile, the ⌬phaC2 mutant produced more PHA than the wild type under this condition, and surprisingly, the phaC3 transcript increased in the ⌬phaC2 background. A double mutant, the ⌬phaC2 ⌬phaC3 mutant, consistently accumulated less PHA than the ⌬phaC2 mutant. PHA accumulation in nodule bacteroids followed a pattern similar to that seen in liquid cultures, being prevented in the ⌬phaC1 mutant and increased in the ⌬phaC2 mutant in relation to the level in the wild type. Therefore, we used these mutants, together with a ⌬phaC1 ⌬phaC2 double mutant, to study the B. japonicum PHA requirements for survival, competition for nodulation, and plant growth promotion. All mutants, as well as the wild type, survived for 60 days in a carbon-free medium, regardless of their initial PHA contents. When competing for nodulation against the wild type in a 1:1 proportion, the ⌬phaC1 and ⌬phaC1 ⌬phaC2 mutants occupied only 13 to 15% of the nodules, while the ⌬phaC2 mutant occupied 81%, suggesting that the PHA polymer is required for successful competitiveness. However, the bacteroid content of PHA did not affect the shoot dry weight accumulation.

show abstract

Heterologous complementation of the exopolysaccharide synthesis and carbon utilization phenotypes ofSinorhizobium melilotiRm1021 polyhydroxyalkanoate synthesis mutants

Cited by 39 publications

References 45 publications

Influence of the Poly-3-Hydroxybutyrate (PHB) Granule-Associated Proteins (PhaP1 and PhaP2) on PHB Accumulation and Symbiotic Nitrogen Fixation in Sinorhizobium meliloti Rm1021

Influence of the Poly-3-Hydroxybutyrate (PHB) Granule-Associated Proteins (PhaP1 and PhaP2) on PHB Accumulation and Symbiotic Nitrogen Fixation in Sinorhizobium meliloti Rm1021

Production, optimization and characterization of polyhydroxybutyrate, a biodegradable plastic by Bacillus spp.

Analysis of Two Polyhydroxyalkanoate Synthases in Bradyrhizobium japonicum USDA 110

Contact Info

Product

Resources

About