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Signal transduction and adaptive regulation through bacterial two-component systems: the Escherichia coli AtoSC paradigm
No full textJournal URL: http://www.springer.at/amino_acidsAdaptive signal transduction within microbial cells involves a multi-faceted regulated phosphotransfer mechanism that comprises structural rearrangements of sensor histidine kinases upon ligand-binding and phosphorylation- induced conformational changes in response regulators of versatile two-component systems (TCS), arisen early in bacterial evolution. In Escherichia coli, cross-talk between the AtoS histidine kinase and the AtoC response regulator, forming the AtoSC TCS, through His ? Asp phosphotransfer, activates AtoC directly to induce atoDAEB operon expression, thus modulating diverse fundamental cellular processes such as short-chain fatty acid catabolism, poly-(R)-3-hydroxybutyrate biosynthesis and chemotaxis. Among the inducers hitherto identified, acetoacetate is the classical activator. The AtoSC TCS functional modulation by polyamines, histamine and Ca2?, as well as the role of AtoC as transcriptional regulator, add new promising perspectives in the physiological significance and potential pharmacological exploitation of this TCS in cell proliferation, bacteria–host interactions, chemotaxis, and adaptation
Καινοτομία Έρευνα και Τεχνολογία. τ.68, Ανοικτή Πρόσβαση: Όταν η γνώση συναντά την κοινωνία
No full text36 σ.: εικ., πίνακεςΤεύχος Σεπτέμβριος - Οκτώβριος 200
Ποσοτικός χαρακτηρισμός υλικών στην γραμμή παραγωγής: Βιομηχανική εφαρμογή φασματοσκοπίας εγγύς υπερύθρου
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Αφιέρωμα στον Γιάννη Ρίτσο: Ομιλία, απαγγελίες, μουσικό πρόγραμμα, προβολές
No full textΤο 2009 ανακηρύχθηκε από το Υπουργείο Πολιτισμού έτος Γιάννη Ρίτσου με αφορμή τη συμπλήρωση 100 χρόνων από τη γέννησή του. Το Εθνικό Ίδρυμα Ερευνών, αναγνωρίζοντας την προσφορά του μεγάλου Έλληνα ποιητή στον πολιτισμό, συμμετέχει στον εορτασμό διοργανώνοντας ένα αφιέρωμα για να τιμήσει τη μνήμη του
E. coli genome-wide promoter analysis in search for potential AtoC target elements
No full textJournal URL: http://www3.interscience.wiley.com/journal/119878145Abstract Poster PresentationThe AtoSC two-component system in E. coli activates atoDAEB operon genes to catabolize short-chain fatty acids, acetoacetate being the inducer. The AtoC response regulator was first described as the Antizyme of the polyamine biosynthetic ornithine decarboxylase. The AtoC binding site within the ato promoter was experimentally verified as an inverted 20 bp palindromic repeat. Transcriptome and phenotypic analyses however, indicated the involvement of atoSC to various other cellular activities, such as flagellar synthesis. Here we report a bioinformatic analysis for the localization of the AtoC binding motif within the E. coli genome that could indicate a putative implication, direct or indirect, of the AtoC in other operons regulation. A genome-wide promoter analysis was performed using a program for the de novo detection of overrepresented motifs within promoters. The motif sampling was initiated using the intergenic region where the AtoC binding site is located. By applying an iterative algorithm, including TCS regulated promoters, the program resulted to promoter sets comprising high-scoring putative cis-regulatory elements. The AtoC binding ability to these elements was tested by chromatin immunoprecipitation, using anti-AtoC polyclonal antibody. MotifScanner identified occurrences of different motifs connected to the ato palindromic sequence, and those related to established AtoC functions were singled out and used as templates for the design of primers, in order to analyse the immunoprecipitated chromatin in strains lacking or comprising atoSC, with or without acetoacetate induction. Experimental verification of predicted correlations could provide an insight to gene regulatory networks in bacteria, enabling us to foresee potential targets for response regulators