Identification of Pseudomonas proteins coordinately induced by acidic amino acids and their amides: a two-dimensional electrophoresis study.

The acidic amino acids (Asp, Glu) and their amides (Asn, Gln) are excellent growth substrates for many pseudomonads. This paper presents proteomics data indicating that growth of Pseudomonas fluorescens ATCC 13525 and Pseudomonas putida KT2440 on these amino acids as sole source of carbon and nitrogen leads to the induction of a defined set of proteins. Using mass spectrometry and N-terminal sequencing, a number of these proteins were identified as enzymes and transporters involved in amino acid uptake and metabolism. Most of them depended on the alternative sigma factor sigma(54) for expression and were subject to strong carbon catabolite repression by glucose and citrate cycle intermediates. For a subset of the identified proteins, the observed regulatory effects were independently confirmed by RT-PCR. The authors propose that the respective genes (together with others still to be identified) make up a regulon that mediates uptake and utilization of the abovementioned amino acids.