title: Repression of the glucose-inducible outer-membrane protein OprB during utilization of aromatic compounds and organic acids in Pseudomonas putida CSV86.
abstract: Pseudomonas putida CSV86 shows preferential utilization of aromatic compounds over glucose. Protein analysis and [¹⁴C]glucose-binding studies of the outer membrane fraction of cells grown on different carbon sources revealed a 40 kDa protein that was transcriptionally induced by glucose and repressed by aromatics and succinate. Based on 2D gel electrophoresis and liquid chromatography-tandem mass spectrometry analysis, the 40 kDa protein closely resembled the porin B of P. putida KT2440 and carbohydrate-selective porin OprB of various Pseudomonas strains. The purified native protein (i) was estimated to be a homotrimer of 125 kDa with a subunit molecular mass of 40 kDa, (ii) displayed heat modifiability of electrophoretic mobility, (iii) showed channel conductance of 166 pS in 1 M KCl, (iv) permeated various sugars (mono-, di- and tri-saccharides), organic acids, amino acids and aromatic compounds, and (v) harboured a glucose-specific and saturable binding site with a dissociation constant of 1.3 µM. These results identify the glucose-inducible outer-membrane protein of P. putida CSV86 as a carbohydrate-selective protein OprB. Besides modulation of intracellular glucose-metabolizing enzymes and specific glucose-binding periplasmic space protein, the repression of OprB by aromatics and organic acids, even in the presence of glucose, also contributes significantly to the strain's ability to utilize aromatics and organic acids over glucose.
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.
authors.forename: Rahul
authors.initials: R
authors.lastname: Shrivastava
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India.
authors.forename: Bhakti
authors.initials: B
authors.lastname: Basu
authors.affiliation: National Center for Biological Sciences, Bangalore 560 065, India.
authors.forename: Ashwini
authors.initials: A
authors.lastname: Godbole
authors.affiliation: National Center for Biological Sciences, Bangalore 560 065, India.
authors.forename: M K
authors.initials: MK
authors.lastname: Mathew
authors.affiliation: Molecular Biology Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085, India.
authors.forename: Shree K
authors.initials: SK
authors.lastname: Apte
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology-Bombay, Powai, Mumbai 400 076, India.
authors.forename: Prashant S
authors.initials: PS
authors.lastname: Phale
mesh_terms: D000143:Acids / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism*; D006841:Hydrocarbons, Aromatic / Q000378:metabolism*; D013058:Mass Spectrometry; D008970:Molecular Weight; D018272:Porins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016958:Pseudomonas putida / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000143:Acids; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D006841:Hydrocarbons, Aromatic; C086247:OprB protein, Pseudomonas; D018272:Porins; D005947:Glucose