Engineering Pseudochelin Production in Myxococcus xanthus.

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Myxobacteria use siderophores like myxochelin A and B for iron homeostasis.
• Pseudoalteromonas piscicida S2040 produces myxochelin A, B, and a derivative, pseudochelin A, featuring an imidazoline ring.
• The imidazoline moiety in pseudochelin A was hypothesized to form from myxochelin B via intramolecular condensation.

Purpose of the Study:

• To identify the enzyme responsible for pseudochelin A formation from myxochelin B.
• To confirm the enzyme's activity in vitro and in vivo.
• To establish a heterologous expression system for pseudochelin A biosynthesis in Myxococcus xanthus.

Main Methods:

• Comparative analysis of myxochelin regulons between different bacterial strains.
• In vitro enzymatic assays using recombinant amidohydrolase and myxochelin B.
• Heterologous expression of the identified amidohydrolase gene in Myxococcus xanthus using inducible and constitutive promoters.

Main Results:

• A novel amidohydrolase gene, exclusive to the P. piscicida S2040 myxochelin regulon, was identified.
• In vitro reconstitution confirmed the enzyme's ability to convert myxochelin B to pseudochelin A.
• Heterologous expression in M. xanthus successfully produced pseudochelin A, with increased yields using a constitutive promoter.

Conclusions:

• The identified amidohydrolase is responsible for imidazoline formation in pseudochelin biosynthesis.
• This study demonstrates successful heterologous gene expression in M. xanthus without chromosomal integration.
• M. xanthus serves as a viable host for reconstituting and manipulating biosynthetic pathways, expanding expression strategies for myxobacteria.