The Pseudomonas aeruginosa Chemotaxis Methyltransferase CheR1 Impacts on Bacterial Surface Sampling

The characterization of factors contributing to the formation and development of surface-associated bacterial communities known as biofilms has become an area of intense interest since biofilms have a major impact on human health, the environment and industry. Various studies have demonstrated that motility, including swimming, swarming and twitching, seems to play an important role in the surface colonization and establishment of structured biofilms. Thereby, the impact of chemotaxis on biofilm formation has been less intensively studied. Pseudomonas aeruginosa has a very complex chemosensory system with two Che systems implicated in flagella-mediated motility. In this study, we demonstrate that the chemotaxis protein CheR1 is a methyltransferase that binds S-adenosylmethionine and transfers a methyl group from this methyl donor to the chemoreceptor PctA, an activity which can be stimulated by the attractant serine but not by glutamine. We furthermore demonstrate that CheR1 does not only play a role in flagella-mediated chemotaxis but that its activity is essential for the formation and maintenance of bacterial biofilm structures. We propose a model in which motility and chemotaxis impact on initial attachment processes, dispersion and reattachment and increase the efficiency and frequency of surface sampling in P. aeruginosa

Clinical evaluation of the neuroprotective effect of alpha-tocopherol against glaucomatous damage

PURPOSE. To evaluate the vasoregulatory effect of antioxidant alpha-tocopherol on retina via protein kinase C pathway

The influence of chernobyl on the radiocesium contamination in lichens in Turkey

Lichen samples collected before and after the Chernobyl accident were analysed for radiocesium activity. 137Cs activity was detected in some samples collected before Chernobyl. 134Cs and 137Cs were detected in all the samples after the accident. The levels of the total cesium activity counted in the samples proved that the eastern region of the Black Sea was affected by Chernobyl at a very high degree compared with other parts of Turkey. © 1992, Taylor & Francis Group, LLC. All rights reserved

Structural and mechanistic determinants of c-di-GMP signalling

Bis-(3'-5' -cyclic dimeric GMP (c-di-GMP) is a ubiquito us second messenger that regulates cell surface-associated traits in bacteria. Components of this regulatory network include GGDEF and EAL domain-containing proteins that det ermine the cellular concentrations of c-di-GMP by mediatin g its synthesis and degradation, respectively. Crystal str ucture analyses in combination with functional studies have revealed the catalytic mechanisms and regulatory princip les involved. Downstream, c-di-GMP is recognized by PilZ d omain-containing receptors that can undergo large-scale do main rearrangements on ligand binding. Here, we review rec ent data on the structure and functional properties of the protein families that are involved in c-di-GMP signalling and discuss the mechanistic implications