Polyhydroxyalkanoate synthases PhaC1 and PhaC2 from Pseudomonas stutzeri 1317 had different substrate specificities

Area of Science:

• Microbiology
• Biochemistry
• Polymer Science

Background:

• Polyhydroxyalkanoates (PHAs) are biodegradable polyesters synthesized by various microorganisms.
• Understanding the genetic basis and enzymatic mechanisms of PHA synthesis is crucial for optimizing production and tailoring polymer properties.

Purpose of the Study:

• To clone and characterize the PHA synthesis gene locus from Pseudomonas stutzeri strain 1317.
• To investigate the substrate specificity of the cloned PHA synthase enzymes, PhaC1Ps and PhaC2Ps.

Main Methods:

• Polymerase Chain Reaction (PCR) cloning strategy was employed to isolate the PHA synthesis gene locus.
• Sequence analysis was performed on the cloned genes (phaC1Ps, phaC2Ps, phaZPs).
• Functional expression of phaC1Ps and phaC2Ps in recombinant Escherichia coli strains for substrate specificity comparison.

Main Results:

• The PHA synthesis gene locus, including phaC1Ps, phaC2Ps, and phaZPs, was successfully cloned from P. stutzeri 1317.
• Sequence analysis revealed high homology of these genes to known Pseudomonas PHA loci.
• Expressed PhaC1Ps and PhaC2Ps exhibited different substrate specificities: PhaC2Ps incorporated both short-chain-length and medium-chain-length 3-hydroxyalkanoates (mcl 3HA), while PhaC1Ps preferentially polymerized mcl 3HA.

Conclusions:

• The study successfully cloned and characterized key PHA synthesis genes from P. stutzeri 1317.
• The distinct substrate specificities of PhaC1Ps and PhaC2Ps offer potential for producing PHAs with tailored compositions.
• These findings contribute to the understanding of PHA biosynthesis diversity in Pseudomonas species.