Two different pathways are involved in the β‐oxidation of n ‐alkanoic and n ‐phenylalkanoic acids in Pseudomonas putida U: genetic studies and biotechnological applications
2001; Wiley; Volume: 39; Issue: 4 Linguagem: Inglês
10.1046/j.1365-2958.2001.02296.x
ISSN1365-2958
AutoresElı́as R. Olivera, David Carnicero, Belén Prieto García, Baltasar Miñambres, M. Valle, Librada M. Cañedo, Concetta Dirusso, Germán Naharro, José M. Luengo,
Tópico(s)Enzyme Catalysis and Immobilization
ResumoIn Pseudomonas putida U, the degradation of n ‐alkanoic and n ‐phenylalkanoic acids is carried out by two sets of β‐oxidation enzymes (β I and β II ). Whereas the first one (called β I ) is constitutive and catalyses the degradation of n ‐alkanoic and n ‐phenylalkanoic acids very efficiently, the other one (β II ), which is only expressed when some of the genes encoding β I enzymes are mutated, catabolizes n ‐phenylalkanoates ( n > 4) much more slowly. Genetic studies revealed that disruption or deletion of some of the β I genes handicaps the growth of P. putida U in media containing n ‐alkanoic or n ‐phenylalkanoic acids with an acyl moiety longer than C 4 . However, all these mutants regained their ability to grow in media containing n ‐alkanoates as a result of the induction of β II , but they were still unable to catabolize n ‐phenylalkanoates completely, as the β I ‐FadBA enzymes are essential for the β‐oxidation of certain n ‐phenylalkanoyl‐CoA derivatives when they reach a critical size. Owing to the existence of the β II system, mutants lacking β I fad B/A are able to synthesize new poly 3‐OH‐ n ‐alkanoates (PHAs) and poly 3‐OH‐ n ‐phenylalkanoates (PHPhAs) efficiently. However, they are unable to degrade these polymers, becoming bioplastic overproducer mutants. The genetic and biochemical importance of these results is reported and discussed.
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