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Characterisation of actinomycete integrative and conjugative elements

25 April 2008

PhD ceremony: E.M. te Poele, 14.45 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Characterisation of actinomycete integrative and conjugative elements

Promotor: prof. L. Dijkhuizen

Faculty: Mathematical and Natural Sciences

 

Evelien te Poele describes in her thesis the study of small DNA-elements present in actinomycetes. These so-called actinomycete integrative and conjugative elements (AICEs) are integrated in a specific tRNA gene of the host genome, and are capable of conjugative transfer. Her research has provided more insight into the functional properties, origin and evolution of AICEs. One of the most important results is the identification of a unique replication initiator protein, RepAM. This protein forms the basis of a novel group of AICEs, the pMEA-elements, to which for example pMEA300 of Amycolatopsis methanolica belongs to.

Furthermore, screening of a large collection of Amycolatopsis isolates for pMEA-specific sequences allowed the identification of multiple pMEA-like elements. These elements could be separated into two distinct populations from different geographical origins. One group was found in isolates from Australia and Asia and the other group was present in European isolates. Apparently, Amycolatopsis strains dispersed at some point in its evolution, giving rise to the Australasian and European lineages with which the elements coevolved.

Database searches of bacterial genome sequences showed that AICEs are present in diverse genera of actinomycetes. It appears that AICEs have a highly conserved structural organisation, with functional modules for excision/integration, replication, conjugative transfer, and regulation. Analysis of these newly found AICEs and their host genomes indicates that AICEs act as modulators of host genome diversity and are also involved in the acquisition of secondary metabolite clusters and foreign DNA via horizontal gene transfer. The data provided suggest the AICEs play an important role in the evolution of actinomycetes.

 

Last modified:15 September 2017 3.37 p.m.
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