Multiple and interconnected pathways for L-lysine catabolism in Pseudomonas putida KT2440

Area of Science:

• Microbial metabolism
• Biochemistry
• Genetics

Background:

• L-lysine catabolism in Pseudomonas putida KT2440 was traditionally attributed to the aminovalerate pathway.
• The existence and significance of alternative L-lysine degradation routes remained largely unexplored.

Purpose of the Study:

• To elucidate the complete L-lysine catabolism pathways in Pseudomonas putida KT2440.
• To identify novel genes and enzymes involved in L-lysine metabolism.
• To understand the interplay between different catabolic pathways.

Main Methods:

• Genetic analysis of Pseudomonas putida KT2440 mutants.
• Stable isotope labeling experiments using L-[U-13C, U-15N]lysine.
• Enzyme activity assays and gene identification.

Main Results:

• Demonstrated the operation of the alternative aminoadipate pathway alongside the aminovalerate pathway.
• Identified new genes (davB, davA, amaA, dkpA, amaB) crucial for both pathways.
• Confirmed that mutations in either pathway impair L-lysine utilization as a sole carbon and nitrogen source.
• Revealed interconnections between the D- and L-lysine pathways and at the aminoadipate-glutarate conversion step.

Conclusions:

• Established the simultaneous operation of both aminovalerate and aminoadipate pathways for L-lysine catabolism in P. putida KT2440.
• Highlighted the critical role of these pathways in microbial fitness and plant-rhizosphere interactions.
• Provided a comprehensive understanding of gene-enzyme relationships in L-lysine metabolism.