Abstract
Four pap genes (papA, papB, papC, papM) were found by sequencing near
to snbA, a Streptomyces pristinaespiralis gene which was previously
shown to encode one of the pristinamycin I (PI) synthetases. Analysis
of the homologies observed from the deduced amino acid sequences
suggested that these four genes could be involved in the biosynthesis
of the PI precursor 4-dimethylamino-L-phenylalanine (DMPAPA). This
was first verified when disruption of papA in S. pristinaespiralis
led to a PI- phenotype, which was reversed by the addition of DMPAPA
into the culture medium. Further confirmation was obtained when
papM was overexpressed in Escherichia coli and the corresponding
protein purified to homogeneity. It catalysed the two successive
N-methylation steps of 4-amino-L-phenylalanine leading to DMPAPA
via 4-methylamino-L-phenylalanine. These results allowed us to assign
a function to each of the four pap genes and to propose a biosynthetic
pathway for DMPAPA.
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