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Title: Analysis of quorum sensing and prodigiosin biosynthetic genes in Serratia marcescens
Author: Harris, A. K. P.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2003
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Serratia marcescens 274 contains a prodigiosin biosynthetic gene cluster, termed the pig cluster. The pig cluster contains 14 pig genes, pigA to N that were cloned on the cosmid pPIG4. The pPIG4 cosmid was able to direct the synthesis of prodigiosin in Escherichia coli. This is the first example of reconstitution of prodigiosin synthesis in this host. pPIG4 also encoded production of pigment in a biosynthetic mutant of Serratia sp. 39006, though not in Erwinia carotovora subsp. carotovora. The pigments from Serratia sp. 39006 and S. marcescens 274 were purified and analysed using ES-MS. The pig genes, pigA to N, were sequenced, as were the genes flanking the cluster: cueR 5’ of pigA and copA 3’ of pigN. The pig gene cluster is arranged similarly to the Serratia sp. 39006 pig cluster, with pigABCDEFGHJKLMN all in one direction of transcription, suggesting an operon. Two striking differences between the Serratia sp. 39006 and the S. marcescens 274 pig clusters are that (1) the Serratia sp. 39006 pig cluster contains an extra gene, pigO, the product of which shows low similarity to a VirR related protein and (2) the S. marcescens 274 pig cluster is flanked by cueR and copA homologues. These genes, which encode a regulator and a copper transporter respectively, are typically adjacent and divergently transcribed in other bacteria. The Serratia sp. 39006 and S. marcescens 274 pig genes encode proteins that are from 52 to 85% similar to each other. The pig genes also show similarity to genes found in the red cluster of Streptomyces coelicolor. The red cluster encodes 23 proteins that direct the synthesis of undecylprodigiosin. At least 12 of the red genes have homologues among the pig genes. Red and Pig homologues share between 23 to 43% similarity with each other. The order and orientation of the red genes compared to the pig genes is completely different, indicating gene rearrangement if these two clusters arose by divergent evolution.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available