l-3,4-Dihydroxyphenyl alanine-extradiol cleavage is followed by intramolecular cyclization in lincomycin biosynthesis.
The LmbB1 protein, participating in the biosynthesis of lincomycin, was heterologously expressed in Escherichia coli, purified in its active form, and characterized as a dimer of identical subunits. Methods for purification and analysis of the LmbB1 reaction product were developed. Molecular mass and fragmentation pattern of the product revealed by capillary electrophoresis-mass spectrometry were in agreement with its proposed structure, 4-(3-carboxy-3-oxo-propenyl)-2,3-dihydro-1H-pyrrole-2-carboxylic acid. The LmbB1 is therefore a dioxygenase catalysing the 2,3-extradiol cleavage of the l-3,4-dihydroxyphenyl alanine aromatic ring. The final LmbB1 reaction product, a unique compound found in biosynthesis of lincomycin and expected in anthramycins, arises through subsequent cyclization of the primary cleavage product, 2,3-secodopa. A possible role of LmbB1 in 2,3-secodopa cyclization and alternative ways of the cyclization in the formation of biosynthetically related compounds, muscaflavin and stizolobinic acid, are discussed.
Novotná
Jitka
J
Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská, Praha, Czech Republic. jinov@biomed.cas.cz
Honzátko
Ales
A
Bednár
Petr
P
Kopecký
Jan
J
Janata
Jirí
J
Spízek
Jaroslav
J
D002852:Chromatography, Ion Exchange; D003500:Cyclization; D004295:Dihydroxyphenylalanine / Q000378:metabolism*; D019075:Electrophoresis, Capillary; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D004958:Estradiol / Q000378:metabolism*; D008034:Lincomycin / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D013058:Mass Spectrometry; D015394:Molecular Structure; D013302:Streptomyces / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D004958:Estradiol; D004295:Dihydroxyphenylalanine; D008034:Lincomycin