Regulation of Pseudomonas putida genes involved in the metabolism of acidic amino acids
Pseudomonas putida KT2440 has the ability to utilize a wide range of amino acids as carbon and nitrogen sources. Rapid growth of this organism is supported by the acidic amino acids (Asp and Glu) and their amides (Asn and Gln) when supplied as sole source of carbon and nitrogen, or in combination wi...
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|Pseudomonas putida KT2440 has the ability to utilize a wide range of amino acids as carbon and nitrogen sources. Rapid growth of this organism is supported by the acidic amino acids (Asp and Glu) and their amides (Asn and Gln) when supplied as sole source of carbon and nitrogen, or in combination with other carbon and nitrogen sources such as glucose and NH4+. A proteomics study based on two-dimensional gel electrophoresis revealed that during growth of P. putida KT2440 in Glu containing medium a set of at least 9 major proteins were up-regulated in a coordinate fashion, whereas 4 other proteins were specifically induced during growth in NH4+/Glucose. Most of the identified proteins have some role in the uptake and utilization of amino acids. Based on their assigned functions genetic organization, we propose that they form a regulon involved in the metabolism of amino acids. By transposon mutagenesis it was found that the expression of that regulon depends on a functional gltB gene which encodes the major subunit of glutamate synthase (GOGAT). Finally, a novel two-component system (aau) was identified which seems to be involved in the utilization of acidic amino acids. Disruption mutants defective in the response regulator (AauR) and the sensor kinase component (AauS), respectively, were constructed and the resulting phenotype analyzed. Growth of both mutants was severely impaired in glutamate and glutamine-containing media. By contrast, both strains grew at normal rates when succinate was supplied in addition to amino acids. This finding indicate that the aau system is related to, but not identical with the dct two-component system which is involved in the utilization of succinate by rhizobia.