Characterization of the replication region of the Bacillus subtilis plasmid pLS20: a novel type of replicon.

AUTOR(ES)

Meijer, W J

RESUMO

A 3.1 kb fragment of the large (approximately 55 kb) Bacillus subtilis plasmid pLS20 containing all the information for autonomous replication was cloned and sequenced. In contrast to the parental plasmid, derived minireplicons were unstably maintained. Using deletion analysis the fragment essential and sufficient for replication was delineated to 1.1 kb. This 1.1 kb fragment is located between two divergently transcribed genes, denoted orfA and orfB, neither of which is required for replication. orfA shows homology to the B.subtilis chromosomal genes rapA (spoOL, gsiA) and rapB (spoOP). The 1.1 kb fragment, which is characterized by the presence of several regions of dyad symmetry, contains no open reading frames of more than 85 codons and shows no similarity with other known plasmid replicons. The structural organization of the pLS20 minimal replicon is entirely different from that of typical rolling circle plasmids from Gram-positive bacteria. The pLS20 minireplicons replicate in polA5 and recA4 B.subtilis strains. Taken together, these results strongly suggest that pLS20 belongs to a new class of theta replicons.

Documentos Relacionados

• Bacillus subtilis (natto) plasmid pLS20 mediates interspecies plasmid transfer.
• Identification of the origin and direction of replication of the broad-host-range plasmid pLS1.
• Cloning and characterization of the Inc A/C plasmid RA1 replicon.
• Purification and characterization of RepA, a protein involved in the copy number control of plasmid pLS1.
• In vitro recognition of the replication origin of pLS1 and of plasmids of the pLS1 family by the RepB initiator protein.