I quote the passages from:
Giant plasmid-encoded polyketide synthases produce the macrolide toxin of Mycobacterium ulcerans
"...MU contains a 174-kb plasmid, pMUM001, bearing a cluster of genes encoding giant polyketide synthases (PKSs), and polyketide-modifying enzymes, and demonstrate that these are necessary and sufficient for mycolactone synthesis."
"...reflects the acquisition of pMUM001 by horizontal transfer."
"...The 12-membered core of mycolactone is produced by two giant, modular PKSs,
MLSA1 (1.8 MDa) and MLSA2 (0.26 MDa), whereas its side chain is synthesized by MLSB (1.2 MDa), a third modular PKS highly related to MLSA1."
"...There is an extreme level of sequence identity within the different domains of the MLS cluster (>97% amino acid identity), so much so that the 16 ketosynthase domains seem functionally identical."
"..confirming the existence in MU of a circular plasmid, designated pMUM001, comprising 174,155 bp, with a GC content of 62.8% and carrying 81 protein-coding DNA sequences."
"..Replication seems to be initiated by the predicted product of repA, which shares
68.3% amino acid identity with RepA from the cryptic Mycobacterium fortuitum plasmid, pJAZ38 (10)"
"..Two different direct repeat regions were identified 500–1,000 bp upstream of repA, suggesting possible replication origins (ori). GC-skew plots [(G - C) (G+ C)], which highlight compositional biases between leading and lagging DNA strands, displayed a random pattern and did not help pinpoint a possible ori (Fig. 2)."
"..Approximately 2 kb downstream of repA is parA, a gene encoding a chromosome partitioning protein, required for plasmid segregation on cell division. In this region, there is also a potential regulatory gene cluster composed of a serine threonine protein kinase (mup008), a gene encoding a protein of unknown function(mup018) but containing a phosphopeptide recognition domain,a domain found in many regulatory proteins (11), and a WhiB like transcriptional regulator (mup021)."
"...The plasmid is rich in insertion sequences (IS), with 26 examples, including
4 copies of IS2404 and 8 copies of IS2606 (13)."
Circular presentation of pMUM001:
My contribution to pMUM001 plasmid seen from a new perspective by Dot-plot analysis :
by virtual 2G gel:
PKS,polyketide synthase
KS, ketosynthase
TE, thioesterase
by UGENE
