Abstract

In Pyrococcus furiosus two binding protein–dependent, substrate–specific ABC transporters could be identified, one of it being a trehalose/maltose (TM)–transporter, which is responsible for the uptake of trehalose and maltose. By binding to the respective operator sites TrmB prevents the further binding of transcription factors and subsequent RNA polymerase recruitment, which leads to an inhibition of transcription. With the aid of in vitro transcription assays using purified components of P. furiosus it could be shown that TrmB–mediated inhibition of transcription on both promoters is released by specific carbohydrates with maltose and trehalose being inducers for the TM operon, and maltodextrins as well as sucrose releasing inhibition on the MD promoter.TrmBL1 is homologue to TrmB and is involved in the regulation of genes encoding glycolytic and gluconeogenetic enzymes, respectively, where it recognizes a conserved sequence motif called TGM. It inhibits transcription of glycolytic genes with maltose, maltotriose and fructose as inducers (3). On the other hand TrmBL1 activates the expression of gluconeogenetic genes as well. Since the TGM is not present in the promoter region of the TrmBL1 gene, the TGM is not essential for TrmBL1 target recognition (3).Both TrmB and TrmBL1 share the unique property of recognizing different DNA sequences on different promoters and showing distinctive, promoter–dependent sugar specificity.In vitro transcription assays, EMSA and DNaseI footprinting experiments proved that TrmB and TrmBL1 have at least two different HTH motifs and recognize their respective target promoters with different helices within their N–terminal DNA binding domains.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.