Genome-wide analysis of the regulation of sugar transport in the archaeon Sulfolobus solfataricus

Sulfolobus solfataricus is an organism that belongs to the group of extreme thermoacidophilic
archaea. These grow under very hostile conditions of high temperature and very acidic pH
values, such as found in acidic volcanic mud pools. These environments are low in the availability
of nutrients such as sugars and other organic molecules. The aim of this thesis was to obtain an
insight in the regulation of the uptake of sugars by Sulfolobales. Remarkably, sugar uptake in
these organisms is mediated by high-affinity binding protein dependent ABC transporters that
have the ability to efficiently scavenge sugars at a very low concentration. Our focus was on the
expression and regulation of the arabinose and glucose transporters. While the glucose
transporter is constitutively present, the arabinose transport system is expressed only when the
substrate is present in the growth media. Interestingly, expression of the arabinose transporter is
repressed by a selective group of amino acids suggesting the existence of catabolite repression in
Sulfolobus. In a strain with a gene deletion of an essential component of the arabinose transport
system, two potential candidates for transcriptional regulators of the ara operon are differentially
expressed. Remarkably, this strain is still able to grow on arabinose and this correlates with an
overexpression of a transporter that might be responsible for this alternative uptake of arabinose.
This study suggests a complex mechanism of regulation of sugar transport in Sulfolobales and
the presence of back-up mechanisms to ensure the efficient utilization of sugars and other
carbon sources.

	Title and contents
	Chapter 1
	Chapter 2
	Chapter 3
	Chapter 4
	Chapter 5
	Chapter 6
	Podsumowanie po polsku
	Abbreviations
	References
	Complete thesis

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