Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487256
Title: Nitrilase activity in plant-associated Pseudomonas
Author: Howden, Andrew
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2007
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Abstract:
Pseudomonas fluorescens SBW25 (P.f.SBW25) is a plant growth-promoting rhizobacterium (PGPR) that efficiently colonises the rhizosphere of a range of plants. Previously In Vivo Expression Technology (IVET) has identified a rhizosphereinduced gene (pinA) in P.f.SBW25 that shows homology to members of the nitrilase group of hydrolyzing enzymes. Nitrilase enzymes catalyse the hydrolysis of nitrile ;J) compounds (R-CN) to the corresponding carboxylic acid and ammonia. These enzymes have been described in plants, animals, bacteria and fungi and may be important in hormone synthesis, detoxification of toxic nitriles and nitrogen acquisition. In this investigation· nitrilase activity has been examined in P.f.SBW25 and in a range of other plant-associated Pseudomonas to identify the substrates and potential roles of nitrilase enzymes in bacteria colonising the plant environment. ~-cyanoalanine (AlaCN), a nitrile produced by plants and bacteria during cyanide detoxification, acts as a inducing chemical and a substrate for pinA activity. pinA expression is also induced by the substrates for AlaCN synthesis, cyanide and cysteine. Heterologous expression of pinA in bacteria and plants confers AlaCN hydrolysing activity and increased tolerance to toxic levels of AlaCN, suggesting a role for pinA in AlaCN detoxification. AlaCN-hydrolysing activity has also been observed in Pseudomonas f1uorescens PfO-1 and Pf-5. Nitrilase activity has also been detected in the plant pathogenic bacterium Pseudomonas syringae pv. syringae B728a (P.s.B728a). This bacterium hydrolyses arylacetonitriles, such as indoleacetonitrile, which are abundant in the plant environment and may do so for the purposes of nitrogen utilisation, detoxification or to modify plant growth and development.
Supervisor: Not available Sponsor: Not available
Qualification Name: University of Oxford, 2007 Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.487256  DOI: Not available
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