The large linear plasmid pSLA2-L of Streptomyces rochei has an unusually condensed gene organization for secondary metabolism.
The complete nucleotide sequence of the large linear plasmid pSLA2-L in Streptomyces rochei strain 7434AN4 has been determined. pSLA2-L was found to be 210 614 bp long with a GC content of 72.8% and carries 143 open reading frames. It is especially noteworthy that three-quarters of the pSLA2-L DNA is occupied by secondary metabolism-related genes, namely two type I polyketide synthase (PKS) gene clusters for lankacidin and lankamycin, a mithramycin synthase-like type II PKS gene cluster, a carotenoid biosynthetic gene cluster and many regulatory genes. In particular, the lankacidin PKS is unique, because it may be a mixture of modular- and iterative-type PKSs and carries a fusion protein of non-ribosomal peptide synthetase and PKS. It is also interesting that all the homologues of the afsA, arpA, adpA and strR genes in the A-factor regulatory cascade in Streptomyces griseus were found on pSLA2-L, and disruption of the afsA homologue caused non-production of both lankacidin and lankamycin. These results, together with the finding of three possible replication origins at 50-63 kb from the right end, suggest that the present form of pSLA2-L might have been generated by a series of insertions of the biosynthetic gene clusters into the left side of the original plasmid.
Mochizuki
Susumu
S
Department of Molecular Biotechnology, Hiroshima University, Higashi-Hiroshima 739-8530, Japan.
Hiratsu
Keiichiro
K
Suwa
Masanori
M
Ishii
Tatsuya
T
Sugino
Fuminori
F
Yamada
Kohei
K
Kinashi
Haruyasu
H
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry; D000903:Antibiotics, Antineoplastic / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D019077:Helix-Turn-Helix Motifs; D018942:Macrolides; D008969:Molecular Sequence Data; D005810:Multigene Family; D010957:Plasmids / Q000235:genetics*; D008926:Plicamycin / Q000096:biosynthesis; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D000903:Antibiotics, Antineoplastic; D001426:Bacterial Proteins; D018942:Macrolides; C008250:lankacidins; D004917:Erythromycin; C100149:kujimycin B; D008926:Plicamycin