Identification of caerulomycin A gene cluster implicates a tailoring amidohydrolase

Area of Science:

• Marine microbiology
• Natural product biosynthesis
• Biochemistry

Background:

• Caerulomycin A is a marine natural product with potential biological activities.
• Understanding its biosynthesis is crucial for producing this compound and discovering related molecules.

Purpose of the Study:

• To elucidate the biosynthetic pathway of caerulomycin A.
• To characterize the enzymes involved in its production.
• To enable heterologous production of caerulomycin A.

Main Methods:

• Cloning and characterization of the biosynthetic gene cluster from *Actinoalloteichus cyanogriseus*.
• Construction and analysis of a *crmL* disruption mutant.
• Enzyme assays using crude CrmL extracts.
• Heterologous expression in *Streptomyces coelicolor*.

Main Results:

• The caerulomycin A biosynthetic gene cluster contains a hybrid polyketide synthase/nonribosomal peptide synthetase system.
• A *crmL* disruption mutant accumulated an intermediate (caerulomycin L) with an extra leucine residue.
• CrmL enzyme demonstrated leucine-removing amidohydrolase activity.
• Heterologous expression of the gene cluster in *Streptomyces coelicolor* successfully produced caerulomycin A.

Conclusions:

• The identified gene cluster is responsible for caerulomycin A biosynthesis.
• CrmL is an amidohydrolase that removes a leucine residue during the pathway.
• Heterologous expression provides a viable method for producing caerulomycin A.