Open AccessImpaired polyhydroxybutyrate biosynthesis from glucose in Pseudomonas sp. 14‐3 is due to a defective β‐ketothiolase gene
Author(s) -
Ayub Nicolás D.,
Julia Pettinari M.,
Méndez Beatriz S.,
López Nancy I.
Publication year - 2006
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2006.00446.x
Subject(s) - polyhydroxybutyrate , biosynthesis , pseudomonas , biochemistry , chemistry , gene , biology , microbiology and biotechnology , bacteria , genetics
Pseudomonas sp. 14‐3 accumulates polyhydroxybutyrate (PHB) from octanoate, but not from glucose. To elucidate this unusual phenotype, genes responsible for the synthesis of PHB were cloned and analyzed. A PHB polymerase gene ( phaC ) was found downstream from genes coding for a β‐ketothiolase ( phaA ), an acetoacetyl‐coenzyme A reductase ( phaB ) and a putative transcriptional regulator ( phaR ). All genes were similar to pha genes from several related species, but differences were observed in the distal region of phaA . Complementation with heterologous β‐ketothiolase genes from Azotobacter sp. FA8 or Pseudomonas putida GPp104 restored the capability of Pseudomonas sp. 14‐3 to synthesize PHB from glucose, demonstrating that its β‐ketothiolase was nonfunctional. Analysis of the genome sequences of other Pseudomonas species has revealed the existence of putative β‐ketothiolase genes. The functionality of one of these thiolase genes, belonging to P. putida GPp104, was experimentally demonstrated. Pseudomonas sp. 14‐3 is the first natural phaA mutant described, that despite this mutation accumulates high amounts of PHB when growing on fatty acids.