Physiological consequences of starvation in Pseudomonas putida: degradation of intracellular protein and loss of activity of the inducible enzymes of L-arginine catabolism

Abstract

We investigated the degradation of radioisotopically labeled intracellular protein in starved, intact cells of Pseudomonas putida P2 (ATCC 25571) and the regulation of this process. Intracellular protein isotopically labeled with L-[4,5-'H]leucine during log-phase growth at 30 C is degraded at rates of 1 to 2%/h in log-phase cells and 7 to 9%/h in starved cells. Rifampin, chloramphenicol, and tosyllysine chloromethylketone lower the rate of protein degradation by starved cells. Addition to starved cells of a nutrient upon which the culture is induced for growth rapidly lowers the rate of protein degradation from 7 to 9%/h to less than 1.5%/h. A nutrient that is oxidized but that cannot immediately support growth also lowers the rate of starvation-induced protein degradation. Proteolytic activity of cell extracts requires a divalent metal ion and may be inhibited up to 60% by tosyllysine chloromethylketone or p-toluenesulfonyl fluoride. Rifampin and chloramphenicol have no effect. In contrast to intact cells, extracts of growing or starving cells degrade protein at equivalent rates. We also investigated the stabilities of the inducible transport system and of four inducible intracellular enzymes of L-arginine catabolism. These include: the membraneassociated, L-arginine-specific transport system; L-arginine oxidase (oxidase); a-ketoarginine decarboxylase (decarboxylase); y-guanidinobutyraldehyde dehydrogenase (dehydrogenase); and y-guanidinobutyrate amidinohydrolase (hydro

Surface Colonization and Activity of the 2,6-Dichlorobenzamide (BAM) Degrading Aminobacter sp. Strain MSH1 at Macro- and Micropollutant BAM Concentrations

“…MSH1 cells with reduced BAM degrading activity can be explained by reduced BbdA production due to physiological responses to starvation such as the intracellular degradation of proteins or RNA or both, including BbdA and/or bbdA transcripts. 39 Based on the BAM removal data of experiment 2, we calculated the specific BAM degradation rate in flow systems receiving 1 μg/L BAM 1 day after inoculation as 4.1 ± 0.3 × 10 −12 μg BAM/cell/min, i.e., similar to that of suspended fresh MSH1 cells in batch, supporting our hypothesis that long-term starvation conditions affect degradation. A similar explanation can be assumed for 1 mg/L BAM, which corresponds with 125 μg/L AOC close to the average AOC found in groundwater and presumably as additional AOC in our flow chambers (see above).…”

“…Even viable cells (i.e., cells forming CFU) showed 10 to 20 times lower specific degradation activity compared to that of fresh cells in suspended batch conditions (Table ). MSH1 cells with reduced BAM degrading activity can be explained by reduced BbdA production due to physiological responses to starvation such as the intracellular degradation of proteins or RNA or both, including BbdA and/or bbdA transcripts . Based on the BAM removal data of experiment 2, we calculated the specific BAM degradation rate in flow systems receiving 1 μg/L BAM 1 day after inoculation as 4.1 ± 0.3 × 10 –12 μg BAM/cell/min, i.e., similar to that of suspended fresh MSH1 cells in batch, supporting our hypothesis that long-term starvation conditions affect degradation.…”

The guanidinobutyrase GbuA is essential for the alkylquinolone‐regulated pyocyanin production during parasitic growth of Pseudomonas aeruginosa in co‐culture with Aeromonas hydrophila

“…In this phase of the co-culture strain PAO1 likely faces nutrient limitation. During nutrient limitation bacteria degrade proteins (Postgate and Hunter, 1962;Pine, 1972;Fan and Rodwell, 1975;Miller, 1996) and polyamines (Kim, 1966). It could be speculated that internal metabolites deriving from such degradation, e.g.…”