Hierarchical control of PHA biosynthesis in an Antarctic Pseudomonas strain?

CATONE, M.V.; AYUB, N.D.; MÉNDEZ, B.S.; LÓPEZ, N.I.

Mar del Plata

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Hierarchical control of PHA biosynthesis in an Antarctic Pseudomonas strain? Catone, M.V.; Ayub, N.D.; Méndez, B.S. and López, N.I. Dpto. de Química Biológica. Facultad de Ciencias Exactas y Naturales, UBA. mcatone@qb.fcen.uba.ar   Pseudomonas sp. 14-3 is an Antarctic strain isolated in our laboratory that accumulates high amounts of polyhydroxyalkanoates (PHA) in form of polyhydroxybutyrate (PHB) a polymer composed by short chain length monomers. Recently, PHB genes have been characterized. This strain accumulates only PHB when grown on octanoate supplemented medium and no other medium chain length polymer is detected. However, analysis of the polymer production in a phaC mutant strain, unable to accumulate PHB, showed PHA accumulation. In this work we looked for PHA genes in the mutant strain, quantified its PHA production and analyzed the phylogenetic relationships of these genes. Determination of the composition of polymer showed that the wild type and the complemented mutant strain produced only PHB indicating the functionality of classI polymerase (PhaC). By contrast, the mutant strain produced PHA composed by C8 monomers (14.4 ± 1.2 wt %) suggesting that a classII polymerase is involved and a probable hierarchic control of PHA synthesis. PCR amplification and sequencing allowed identify a classII polymerase (phaC2) and phylogenetic analysis showed its association with other Pseudomonas species. These results in line with other literature data could suggest an evolution of PHA biosynthesis in Pseudomonas by gene displacement that probably is associated with a complex net of regulatory mechanisms.