FleQ of Pseudomonas putida KT2440 is a multimeric cyclic diguanylate binding protein that differentially regulates expression of biofilm matrix components.

The intracellular signal molecule cyclic di-GMP (c-di-GMP) is an important element in regulation of biofilm formation by bacteria. In Pseudomonas aeruginosa, FleQ functions as a c-di-GMP-dependent transcriptional regulator of expression of flagellar genes and the exopolysaccharide (EPS) Pel, a component of the biofilm extracellular matrix. In the plant-beneficial bacterium Pseudomonas putida KT2440, a mutation in fleQ reduces biofilm formation and colonization of plant surfaces.

Molecular Binding Mechanism of TtgR Repressor to Antibiotics and Antimicrobials.

A disturbing phenomenon in contemporary medicine is the prevalence of multidrug-resistant pathogenic bacteria. Efflux pumps contribute strongly to this antimicrobial drug resistance, which leads to the subsequent failure of clinical treatments. The TtgR protein of Pseudomonas putida is a HTH-type transcriptional repressor that controls expression of the TtgABC efflux pump, which is the main contributor to resistance against several antimicrobials and toxic compounds in this microbe.

Fish β-parvalbumin acquires allergenic properties by amyloid assembly.

Principles: Amyloids are highly cross-β-sheet-rich aggregated states that confer protease resistance, membrane activity and multivalence properties to proteins, all essential features for the undesired preservation of food proteins transiting the gastrointestinal tract and causing type I allergy.

Methods: Amyloid propensity of β-parvalbumin, the major fish allergen, was theoretically analysed and assayed under gastrointestinal-relevant conditions using the binding of thioflavin T, the formation of sodium dodecyl sulphate- (SDS-) resistant aggregates, circular dichroism spectroscopy and atomic force microscopy fibril imaging. Impact of amyloid aggregates on allergenicity was assessed with dot blot.

Engineering Biological Approaches for Detection of Toxic Compounds: A New Microbial Biosensor Based on the Pseudomonas putida TtgR Repressor.

Environmental contamination by toxic organic compounds and antimicrobials is one of the causes for the recent surge of multidrug-resistant pathogenic bacteria. Monitoring contamination is therefore the first step in containment of antimicrobial resistance and requires the development of simple, sensitive, and quantitative tools that detect a broad spectrum of toxic compounds. In this study, we have engineered a new microbial biosensor based on the ttgR-regulated promoter that controls expression of the TtgABC extrusion efflux pump of Pseudomonas putida, coupled to a gfp reporter.

Novel BRAFI599Ins Mutation Identified in a Follicular Variant of a Papillary Thyroid Carcinoma: A Molecular Modeling Approach.

Objective: BRAF mutations are the most common genetic alteration found in papillary thyroid carcinoma (PTC). Approximately, 90% correspond to BRAFV600E, although other less common BRAF mutations have been described. The aim of this study was to describe a new mutation on BRAF gene discovered on the previous thyroid cytology of a patient diagnosed with a follicular variant of PTC (FV-PTC).

Identification and characterization of the PhhR regulon in Pseudomonas putida.

Pseudomonas putida is a soil microorganism that utilizes aromatic amino acids present in root exudates as a nitrogen source. We have previously shown that the PhhR transcriptional regulator induces phhAB genes encoding a phenylalanine hydroxylase. In this study we show, using microarray assays and promoter fusions, that PhhR is a global regulator responsible for the activation of genes essential for phenylalanine degradation, phenylalanine homeostasis and other genes of unknown function.

Conformational stability and activity of circular Enterocin AS-48 derivatives.

Four AS-48 mutants (Trp24Ala, Gly13Lys, Leu40Lys and Ala53Ser) were obtained by site-directed mutagenesis. The minimal inhibitory concentration of each peptide showed that only residue Trp24 was unquestionably involved in the biological activity. Guanidine hydrochloride-induced unfolding assays showed a three-state transition denaturation process, suggesting a molten-globule-like conformation after the first transition.

Effect of replacing glutamic residues upon the biological activity and stability of the circular enterocin AS-48.

Background: Bacteriocins are antimicrobial peptides produced by bacteria and have a relatively narrow range of activity against closely related strains. AS-48 is a circular bacteriocin produced by Enterococcus faecalis that acts against many gram-positive and some gram-negative bacteria, and could well serve as a natural food preservative and antimicrobial agent. The structure of AS-48 is a five-helix bundle in which a hypothetical plane containing the C(alpha) atoms of E4, E20, E49 and E58 segregates a patch of positively charged residues from the rest of the hydrophobic or uncharged surface residues.

Design and NMR conformational study of a beta-sheet peptide based on Betanova and WW domains.

A good approach to test our current knowledge on formation of protein beta-sheets is de novo protein design. To obtain a three-stranded beta-sheet mini-protein, we have built a series of chimeric peptides by taking as a template a previously designed beta-sheet peptide, Betanova-LLM, and incorporating N- and/or C-terminal extensions taken from WW domains, the smallest natural beta-sheet domain that is stable in absence of disulfide bridges. Some Betanova-LLM strand residues were also substituted by those of a prototype WW domain.