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Sense Changes (sense + change)
Selected AbstractsSaccharomyces cerevisiae plasma membrane nutrient sensors and their role in PKA signalingFEMS YEAST RESEARCH, Issue 2 2010Marta Rubio-Texeira Abstract The ability to elicit a fast intracellular signal leading to an adaptive response is crucial for the survival of microorganisms in response to changing environmental conditions. Therefore, in order to sense changes in nutrient availability, the yeast Saccharomyces cerevisiae has evolved three different classes of nutrient-sensing proteins acting at the plasma membrane: G protein-coupled receptors or classical receptor proteins, which detect the presence of certain nutrients and activate signal transduction in association with a G protein; nontransporting transceptors, i.e. nutrient carrier homologues with only a receptor function, previously called nutrient sensors; and transporting transceptors, i.e. active nutrient carriers that combine the functions of a nutrient transporter and receptor. Here, we provide an updated overview of the proteins involved in sensing nutrients for rapid activation of the protein kinase A pathway, which belong to the first and the third category, and we also provide a comparison with the best-known examples of the second category, the nontransporting transceptors, which control the expression of the regular transporters for the nutrient sensed by these proteins. [source] Long-range effects of chirality in aromatic poly(isocyanide)sJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2006David B. Amabilino Abstract The preparation of optically active atropoisomeric polymers which present chiral backbones, thanks to induction during their synthesis from stereogenic centers, located far away from the skeleton is possible, thanks principally to semirigid conformations of the promesogenic spacers between them. The result is that chiral "information" can be passed as far as 21 Å from the asymmetric center to the carbon atom that forms the polymeric chain in poly(isocyanide)s. The sense of chiral induction in these conformationally rigid polymers parallels the helical sense of the cholesteric phases, as well as to the helical senses of chiral smectic C phases, induced by the monomers in nematic and smectic C phases, respectively. All these phenomena obey the odd,even rules proposed for chiral sense changes in these liquid crystalline phases. Noncovalent interactions play an important part in the induction process, in which steric arguments can be used to justify the inductions observed. The methodology can be used to prepare macromolecules, which display switching behavior upon thermal or electrochemical stimulus. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3161,3174, 2006 [source] LIGHT REGULATION OF PHYCOBILISOME BIOSYNTHESIS AND CONTROL BY A PHYTOCHROME-LIKE PHOTORECEPTORJOURNAL OF PHYCOLOGY, Issue 2000K. Terauchi Ambient light quality changes dramatically affect the composition of light harvesting structures, the phycobilisomes, in many cyanobacterial species. In the cyanobacterium Fremyella diplosiphon, shifts in the ratio of red to green light lead to transcriptional changes and altered synthesis of several phycobilisome components. This process is called complementary chromatic adaptation (CCA). These two colors have opposite effects: red light activates an operon encoding the biliprotein phycocyanin (PC) and inactivates the operon encoding phycoerythrin (PE), whereas green light activates PE synthesis and shuts down PC synthesis. The effects of red and green light on CCA are photoreversible. Thus, CCA is similar to transcriptional processes that are controlled by phytochromes, a family of eukaryotic red/far red photoreversible photoreceptors. We are using molecular genetics to determine the mechanisms by which F. diplosiphon senses changes in the color of light of its environment. Initial mutant generation and complementation lead to the discovery of three CCA regulatory components that are part of a complex two component system. The most interesting of these is RcaE (regulator of chromatic adaptation), a histidine kinase-class protein containing a region in its amino-terminal half with similarity to the chromophore binding domains of phytochromes. Within this region, RcaE contains a cysteine residue in a similar location as that used for covalent attachment of the open-chain tetrapyrrole chromophore in phytochromes. We will present recent data characterizing RcaE, including in vivo analysis of the chromophore that is attached to RcaE, as well as results from our recent isolation of a new CCA regulatory component. [source] Characterization of CetA and CetB, a bipartite energy taxis system in Campylobacter jejuniMOLECULAR MICROBIOLOGY, Issue 5 2008Kathryn T. Elliott Summary The energy taxis receptor Aer, in Escherichia coli, senses changes in the redox state of the electron transport system via an flavin adenine dinucleotide cofactor bound to a PAS domain. The PAS domain (a sensory domain named after three proteins Per, ARNT and Sim, where it was first identified) is thought to interact directly with the Aer HAMP domain to transmit this signal to the highly conserved domain (HCD) found in chemotaxis receptors. An apparent energy taxis system in Campylobacter jejuni is composed of two proteins, CetA and CetB, that have the domains of Aer divided between them. CetB has a PAS domain, while CetA has a predicted transmembrane region, HAMP domain and the HCD. In this study, we examined the expression of cetA and cetB and the biochemical properties of the proteins they encode. cetA and cetB are co-transcribed independently of the flagellar regulon. CetA has two transmembrane helices in a helical hairpin while CetB is a peripheral membrane protein tightly associated with the membrane. CetB levels are CetA dependent. Additionally, we demonstrated that both CetA and CetB participate in complexes, including a likely CetB dimer and a complex that may include both CetA and CetB. This study provides a foundation for further characterization of signal transduction mechanisms within CetA/CetB. [source] | ||||||||||