title: Optical biosensors for environmental monitoring based on computational and biotechnological tools for engineering the photosynthetic D1 protein of Chlamydomonas reinhardtii.
abstract: Homology-based protein modelling and computational screening followed by virtual mutagenesis analyses were used to identify functional amino acids in the D1 protein of the photosynthetic electron transfer chain interacting with herbicides. A library of functional mutations in the unicellular green alga Chlamydomonas reinhardtii for preparing biomediators was built and their interactions with herbicides were calculated. D1 proteins giving the lowest and highest binding energy with herbicides were considered as suitable for preparing the environmental biosensors for detecting specific herbicide classes. Arising from the results of theoretical calculations, three mutants were prepared by site-directed mutagenesis and characterized by fluorescence analysis. Their adsorption and selective recognition ability were studied by an equilibrium-adsorption method. The S268C and S264K biomediators showed high sensitivity and resistance, respectively, to both triazine and urea classes of herbicides. When immobilized on a silicon septum, the biomediators were found to be highly stable, remaining so for at least 1-month at room temperature. The fluorescence properties were exploited and a reusable and portable multiarray optical biosensor for environmental monitoring was developed with limits of detection between 0.8 x 10(-11) and 3.0 x 10(-9), depending on the target analyte. In addition, biomediator regeneration without obvious deterioration in performance was demonstrated.
authors.affiliation: Institute of Crystallography, Area of Research of Rome, Department of Agrofood, CNR, Via Salaria km 29.300, 00015, Monterotondo Scalo, Rome, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Giardi
authors.forename: Viviana
authors.initials: V
authors.lastname: Scognamiglio
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Rea
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rodio
authors.forename: Amina
authors.initials: A
authors.lastname: Antonacci
authors.forename: Maya
authors.initials: M
authors.lastname: Lambreva
authors.forename: Gianni
authors.initials: G
authors.lastname: Pezzotti
authors.forename: Udo
authors.initials: U
authors.lastname: Johanningmeier
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation*; D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D004784:Environmental Monitoring / Q000295:instrumentation*; D004785:Environmental Pollutants / Q000032:analysis; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006540:Herbicides / Q000032:analysis*; D055096:Optical Devices; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D015202:Protein Engineering / Q000379:methods; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D014159:Transducers
chemical_list: D004785:Environmental Pollutants; D006540:Herbicides; D045332:Photosystem II Protein Complex; C422369:photosystem II, psbA subunit