title: Identification of the chelocardin biosynthetic gene cluster from Amycolatopsis sulphurea: a platform for producing novel tetracycline antibiotics.
abstract: Tetracyclines (TCs) are medically important antibiotics from the polyketide family of natural products. Chelocardin (CHD), produced by Amycolatopsis sulphurea, is a broad-spectrum tetracyclic antibiotic with potent bacteriolytic activity against a number of Gram-positive and Gram-negative multi-resistant pathogens. CHD has an unknown mode of action that is different from TCs. It has some structural features that define it as 'atypical' and, notably, is active against tetracycline-resistant pathogens. Identification and characterization of the chelocardin biosynthetic gene cluster from A. sulphurea revealed 18 putative open reading frames including a type II polyketide synthase. Compared to typical TCs, the chd cluster contains a number of features that relate to its classification as 'atypical': an additional gene for a putative two-component cyclase/aromatase that may be responsible for the different aromatization pattern, a gene for a putative aminotransferase for C-4 with the opposite stereochemistry to TCs and a gene for a putative C-9 methylase that is a unique feature of this biosynthetic cluster within the TCs. Collectively, these enzymes deliver a molecule with different aromatization of ring C that results in an unusual planar structure of the TC backbone. This is a likely contributor to its different mode of action. In addition CHD biosynthesis is primed with acetate, unlike the TCs, which are primed with malonamate, and offers a biosynthetic engineering platform that represents a unique opportunity for efficient generation of novel tetracyclic backbones using combinatorial biosynthesis.
authors.affiliation: Acies Bio d.o.o., Tehnološki Park 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Tadeja
authors.initials: T
authors.lastname: Lukežič
authors.affiliation: Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.|Acies Bio d.o.o., Tehnološki Park 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Urška
authors.initials: U
authors.lastname: Lešnik
authors.affiliation: Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CIPKeBiP), Jamova 39, SI-1000 Ljubljana, Slovenia.|Acies Bio d.o.o., Tehnološki Park 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Ajda
authors.initials: A
authors.lastname: Podgoršek
authors.affiliation: Acies Bio d.o.o., Tehnološki Park 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Jaka
authors.initials: J
authors.lastname: Horvat
authors.affiliation: Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Tomaž
authors.initials: T
authors.lastname: Polak
authors.affiliation: Analytical Chemistry Laboratory, National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia.
authors.forename: Martin
authors.initials: M
authors.lastname: Šala
authors.affiliation: Centre of Excellence for Integrated Approaches in Chemistry and Biology of Proteins (CIPKeBiP), Jamova 39, SI-1000 Ljubljana, Slovenia.|Acies Bio d.o.o., Tehnološki Park 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Branko
authors.initials: B
authors.lastname: Jenko
authors.affiliation: Department of Food Science and Technology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
authors.forename: Peter
authors.initials: P
authors.lastname: Raspor
authors.affiliation: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Herron
authors.affiliation: Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, UK.
authors.forename: Iain S
authors.initials: IS
authors.lastname: Hunter
authors.affiliation: Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, CSIC, SODERCAN, C/Albert Einstein 22, 39011, Santander, Spain.|Acies Bio d.o.o., Tehnološki Park 21, SI-1000 Ljubljana, Slovenia.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Petković
mesh_terms: D000192:Actinomycetales / Q000235:genetics* / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D053898:Biosynthetic Pathways / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D016366:Open Reading Frames; D017422:Sequence Analysis, DNA; D013754:Tetracyclines / Q000096:biosynthesis*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D013754:Tetracyclines; C000400:chelocardin