The Lactococcus lactis nisin-sucrose conjugative transposon Tn5276

<p>The aim of the research described in this thesis was to identify and characterize the genetic element carrying the information for nisin biosynthesis and sucrose proficiency, the nisin-sucrose element. The thesis has the following outline. Chapter 2 describes our current knowledge of nisin genetics and the recent advances in the protein engineering of nisin. The cloning and analysis of several parts of the nisin-sucrose element of <em>L. lactis</em> strain NIZO R5 are described in the next two chapters. Chapter 3 deals with the prenisin gene, <em>nis</em> A, and its surrounding region, which includes the insertion sequence IS <em>1068</em> . In Chapter 4, the organization and transcription of the sucrose ( <em>sac</em> ) operon and the characterization of the gene for sucrose-6-phosphate hydrolase are described. The different parts of the nisin-sucrose element were used as DNA probes to investigate the nature and location of this element (Chapter 5). It was shown that the nisin-sucrose element of <em>L. lactis</em> NIZO R5 is a large (70 kb), conjugative transposon, designated Tn <em>5276.</em> Chapter 6 describes the isolation and analysis of the genes that encode the transposition functions of Tn <em>5276.</em> The experiments leading to a model for excision and insertion of Tn <em>5276</em> are described in Chapter 7. Chapter 8 deals with the distribution and evolution of nisin-sucrose elements in <em>L. lactis</em> . The thesis is completed with the summary and concluding remarks (Chapter 9) and a Dutch summary (Chapter 10)