Biosynthesis of the orthosomycin antibiotic avilamycin A: deductions from the molecular analysis of the avi biosynthetic gene cluster of Streptomyces viridochromogenes Tü57 and production of new antibiotics.
BACKGROUND
Streptomyces viridochromogenes Tü57 is the producer of avilamycin A. The antibiotic consists of a heptasaccharide side chain and a polyketide-derived dichloroisoeverninic acid as aglycone. Molecular cloning and characterization of the genes governing the avilamycin A biosynthesis is of major interest as this information might set the direction for the development of new antimicrobial agents.


RESULTS
A 60-kb section of the S. viridochromogenes Tü57 chromosome containing genes involved in avilamycin biosynthesis was sequenced. Analysis of the DNA sequence revealed 54 open reading frames. Based on the putative function of the gene products a model for avilamycin biosynthesis is proposed. Inactivation of aviG4 and aviH, encoding a methyltransferase and a halogenase, respectively, prevented the mutant strains from producing the complete dichloroisoeverninic acid moiety resulting in the accumulation of new antibiotics named gavibamycins.


CONCLUSIONS
The avilamycin A biosynthetic gene cluster represents an interesting system to study the formation and attachment of unusual deoxysugars. Several enzymes putatively responsible for specific steps of this pathway could be assigned. Two genes encoding enzymes involved in post-PKS tailoring reactions were deleted allowing the production of new analogues of avilamycin A.
Weitnauer
G
G
Albert-Ludwigs-Universität Freiburg, Institut für Pharmazeutische Biologie, Germany.
Mühlenweg
A
A
Trefzer
A
A
Hoffmeister
D
D
Süssmuth
R D
RD
Jung
G
G
Welzel
K
K
Vente
A
A
Girreser
U
U
Bechthold
A
A
D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000494:pharmacology; D001426:Bacterial Proteins; D003001:Cloning, Molecular; D023061:Gene Order; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000494:pharmacology; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010226:Parabens / Q000378:metabolism; D011134:Polysaccharides / Q000235:genetics / Q000378:metabolism; D017421:Sequence Analysis; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D009844:Oligosaccharides; D010226:Parabens; D011134:Polysaccharides; C436979:dichloroisoeverninic acid; C436980:gavibamycin A3; C436981:gavibamycin B3; C436978:AviH protein, Streptomyces viridochromogenes; D010088:Oxidoreductases; C436977:AviG4 protein, Streptomyces viridochromogenes; D008780:Methyltransferases; C436976:avilamycin A