The genes lmbB1 and lmbB2 of Streptomyces lincolnensis encode enzymes involved in the conversion of L-tyrosine to propylproline during the biosynthesis of the antibiotic lincomycin A.
The genes lmbA,B1,B2 in the lincomycin A production gene cluster of Streptomyces lincolnensis were shown to form a common transcription unit with the promoter located directly upstream of lmbA. The proteins LmbB1 (mol. mass, 18 kDa) and LmbB2 (mol. mass 34 kDa), when over-produced together in Escherichia coli, brought about enzyme activities for the specific conversion of both L-tyrosine and L-3,4-dihydroxyphenylalanine (L-DOPA) to a yellow-colored product. The LmbB1 protein alone catalyzed the conversion of L-DOPA, but not of L-tyrosine. The purified LmbB1 protein showed a Km for L-DOPA of 258.3 microM. The L-tyrosine converting activity could not been demonstrated in vitro. The preliminary interpretation of these data suggests that the protein LmbB1 is an L-DOPA extradiol-cleaving 2,3-dioxygenase and that the protein LmbB2, either alone or in accord with LmbB1, represents an L-tyrosine 3-hydroxylase. This sequence of putative oxidation reactions on L-tyrosine seems to represent a new pathway different from the ones catalyzed by mammalian L-tyrosine hydroxylases or the wide-spread tyrosinases. The protein LmbA seemed not to be involved in this process. The labile, yellow-colored product from L-DOPA could not be converted to a picolinic acid derivative [3-(2-carboxy-5-pyridyl)alanine] in the presence of ammonia. Therefore, it probably is not a derivative of a cis, cis-3-hydroxymuconic acid semialdehyde; instead, its speculative structure represents a heterocyclic precursor of the propylhygric acid moiety of lincomycin A.
Neusser
D
D
Bergische Universitat GH, Mikrobiologie-FB 9, Gaussstrasse 20, D-42097 Wuppertal, Germany.
Schmidt
H
H
Spizèk
J
J
Novotnà
J
J
Peschke
U
U
Kaschabeck
S
S
Tichy
P
P
Piepersberg
W
W
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000032:analysis / Q000737:chemistry; D001483:Base Sequence; D004295:Dihydroxyphenylalanine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D049308:Dioxygenases; D005798:Genes, Bacterial / Q000235:genetics*; D008034:Lincomycin / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D011392:Proline / Q000031:analogs & derivatives* / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; C067196:3-propylproline; D014443:Tyrosine; D004295:Dihydroxyphenylalanine; D011392:Proline; D008034:Lincomycin; D010105:Oxygenases; D049308:Dioxygenases; C074272:2,3-dihydroxybiphenyl oxygenase; D014446:Tyrosine 3-Monooxygenase