title: Ethyl-substituted erythromycin derivatives produced by directed metabolic engineering.
abstract: A previously unknown chemical structure, 6-desmethyl-6-ethylerythromycin A (6-ethylErA), was produced through directed genetic manipulation of the erythromycin (Er)-producing organism Saccharopolyspora erythraea. In an attempt to replace the methyl side chain at the C-6 position of the Er polyketide backbone with an ethyl moiety, the methylmalonate-specific acyltransferase (AT) domain of the Er polyketide synthase was replaced with an ethylmalonate-specific AT domain from the polyketide synthase involved in the synthesis of the 16-member macrolide niddamycin. The genetically altered strain was found to produce ErA, however, and not the ethyl-substituted derivative. When the strain was provided with precursors of ethylmalonate, a small quantity of a macrolide with the mass of 6-ethylErA was produced in addition to ErA. Because substrate for the heterologous AT seemed to be limiting, crotonyl-CoA reductase, a primary metabolic enzyme involved in butyryl-CoA production in streptomycetes, was expressed in the strain. The primary macrolide produced by the reengineered strain was 6-ethylErA.
authors.affiliation: Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, IL 60064, USA. diane.stassi@abbott.com
authors.forename: D L
authors.initials: DL
authors.lastname: Stassi
authors.forename: S J
authors.initials: SJ
authors.lastname: Kakavas
authors.forename: K A
authors.initials: KA
authors.lastname: Reynolds
authors.forename: G
authors.initials: G
authors.lastname: Gunawardana
authors.forename: S
authors.initials: S
authors.lastname: Swanson
authors.forename: D
authors.initials: D
authors.lastname: Zeidner
authors.forename: M
authors.initials: M
authors.lastname: Jackson
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.forename: A
authors.initials: A
authors.lastname: Buko
authors.forename: L
authors.initials: L
authors.lastname: Katz
mesh_terms: D000214:Acyl Coenzyme A / Q000378:metabolism; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D018942:Macrolides; D008826:Microbial Sensitivity Tests; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010957:Plasmids; D015202:Protein Engineering; D015183:Restriction Mapping; D016930:Saccharopolyspora / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D000214:Acyl Coenzyme A; D000900:Anti-Bacterial Agents; D018942:Macrolides; C102829:ethylmalonyl-coenzyme A; C012454:niddamycin; D004917:Erythromycin