<i>Serratia marcescens </i>274 contains a prodigiosin biosynthetic gene cluster, termed the <i>pig</i> cluster. The <i>pig</i> cluster contains 14 <i>pig</i> genes, <i>pigA</i> to <i>N</i> that were cloned on the cosmid pPIG4. The pPIG4 cosmid was able to direct the synthesis of prodigiosin in <i>Escherichia coli</i>. This is the first example of reconstitution of prodigiosin synthesis in this host. pPIG4 also encoded production of pigment in a biosynthetic mutant of <i>Serratia </i>sp. 39006, though not in <i>Erwinia carotovora</i> subsp. <i>carotovora. </i>The pigments from <i>Serratia </i>sp. 39006 and <i>S. marcescens </i>274 were purified and analysed using ES-MS. The <i>pig </i>genes, <i>pigA</i> to <i>N</i>, were sequenced, as were the genes flanking the cluster: <i>cueR </i>5’ of <i>pigA</i> and <i>copA </i>3’ of <i>pigN. </i>The <i>pig</i> gene cluster is arranged similarly to the <i>Serratia </i>sp. 39006 <i>pig</i> cluster, with <i>pigABCDEFGHJKLMN </i>all in one direction of transcription, suggesting an operon. Two striking differences between the <i>Serratia </i>sp. 39006 and the <i>S. marcescens </i>274 <i>pig </i>clusters are that (1) the <i>Serratia</i> sp. 39006 <i>pig </i>cluster contains an extra gene, <i>pigO</i>, the product of which shows low similarity to a VirR related protein and (2) the <i>S. marcescens </i>274 <i>pig</i> cluster is flanked by <i>cueR</i> and <i>copA</i> homologues. These genes, which encode a regulator and a copper transporter respectively, are typically adjacent and divergently transcribed in other bacteria. The <i>Serratia </i>sp. 39006 and <i>S. marcescens </i>274 <i>pig</i> genes encode proteins that are from 52 to 85% similar to each other. The <i>pig</i> genes also show similarity to genes found in the <i>red </i>cluster of <i>Streptomyces coelicolor</i>. The <i>red</i> cluster encodes 23 proteins that direct the synthesis of undecylprodigiosin. At least 12 of the <i>red</i> genes have homologues among the <i>pig</i> genes. Red and Pig homologues share between 23 to 43% similarity with each other. The order and orientation of the <i>red</i> genes compared to the <i>pig</i> genes is completely different, indicating gene rearrangement if these two clusters arose by divergent evolution.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:603740 |
| Date | January 2003 |
| Creators | Harris, A. K. P. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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