Lysine source for ε-poly-l-lysine biosynthesis depends on diaminopimelate pathway during its production in...

Area of Science:

• Microbiology
• Biochemistry
• Synthetic Biology

Background:

• Streptomyces albulus NBRC14147 produces ε-poly-l-lysine (ε-PL), a valuable antimicrobial biopolymer.
• ε-PL production relies on l-lysine polymerization, necessitating understanding the l-lysine source for yield enhancement.
• In actinobacteria, l-lysine is synthesized via the diaminopimelate (DAP) pathway.

Purpose of the Study:

• To elucidate the source of l-lysine utilized for ε-PL production in S. albulus.
• To investigate the role of the DAP pathway in supplying l-lysine for ε-PL biosynthesis.
• To identify potential targets for modulating ε-PL yield.

Main Methods:

• Comparative structural analysis of DapB enzymes from Mycobacterium tuberculosis and S. albulus.
• In silico identification of 2,6-pyridine-dicarboxylate (PDC) as a potential DapB inhibitor.
• Experimental validation of PDC's inhibitory effect on S. albulus growth and ε-PL production.

Main Results:

• 2,6-pyridine-dicarboxylate (PDC) was identified as an inhibitor of the DAP pathway enzyme DapB.
• PDC addition to S. albulus cultures inhibited bacterial growth.
• PDC addition during early ε-PL production phase caused accumulation of upstream metabolites and terminated ε-PL synthesis.

Conclusions:

• De novo synthesized l-lysine from the DAP pathway is a significant contributor to ε-PL production.
• Inhibiting the DAP pathway effectively halts ε-PL production, confirming the pathway's role.
• Targeting the DAP pathway offers a strategy for controlling and potentially enhancing ε-PL yield.