Glucose uptake and phosphorylation in Pseudomonas fluorescens.

Area of Science:

• Microbiology
• Biochemistry
• Bacterial Physiology

Background:

• Pseudomonas fluorescens utilizes glucose as a carbon source.
• Particulate glucose oxidase (d-glucose:oxygen oxidoreductase, EC 1.1.3.4) is involved in glucose metabolism.
• The necessity of glucose oxidation for glucose uptake remains unclear.

Purpose of the Study:

• To investigate if particulate glucose oxidase activity is essential for glucose uptake in Pseudomonas fluorescens ATCC 13525.
• To elucidate the relationship between glucose transport and glucose catabolism in this bacterium.

Main Methods:

• Comparative analysis of [(14)C]glucose uptake rates in wild-type and a glucose oxidase mutant (gox-7) of P. fluorescens.
• Identification of intracellular glucose metabolites using radiolabeling techniques.
• Enzyme assays for soluble glucose phosphorylation activity.
• Induction studies for glucose transport and catabolism.

Main Results:

• [(14)C]glucose uptake rates were similar in both parent and gox-7 mutant strains.
• Glucose was actively transported and metabolized to glucose-6-phosphate and gluconate-6-phosphate in both strains.
• Soluble kinase activity facilitated glucose phosphorylation.
• Glucose uptake was induced by glucose, not gluconate, indicating independent regulation.

Conclusions:

• Particulate glucose oxidase is not obligatory for glucose permeation in P. fluorescens.
• Glucose transport and catabolism are independently regulated in P. fluorescens.
• A unifying scheme for glucose utilization in aerobic fluorescent pseudomonads is proposed.