Unveiling novel streptomyces developmental signal mediated by ABC transporters

Abstract

Streptomyces spp are gram-positive bacteria known for their ecological diversity, their particular development cycle and their ability to produce numerous bioactive molecules. This ecological and therefore genetic diversity requires the ability of its organisms to be able to use a wide variety of carbon sources serving as signals for the production of enzymes such as glycosyl hydrolases or secondary metabolites. However, at present, the regulatory pathways related to the use of these carbon sources are still poorly known since only 6 systems have been studied to date and it is estimated between 10 and 40, the number of systems still unknown. This is why this work aims to complete and expand knowledge on these systems. To do this, we studied the ability of the binding protein MalE to bind malto-oligosaccharides via different methods (intrinsic fluorescence, affinity column and crystallography), we were also interested in the transcriptional regulator MalR associated with this transport system. And during the second part of this work, we sought to discover which ATP Binding Cassette-transporter (ABC-transporter) was involved in the transport of manno-oligosaccharides by testing a candidate binding protein, ManE2. The results obtained during this work showed the ability of MalE to bind maltose and comparisons with other proteins of known structures suggest an ability to bind maltotriose as well as maltotetraose. We were also able to make progress on the production and purification of MalR. And concerning ManE2 we were able to demonstrate by intrinsic fluorescence experiments its ability to bind mannobiose, mannotiose as well as mannotetraose. This study thus makes it possible to complete the knowledge concerning the use of malto-oligosaccharides as well as to identify a new ABC-transporter for manno-oligosaccharides. Finally, this work allowed the use of various methods allowing to study the interactions proteins ligands and being able to be reused for future studies.