R. BEAUDET, INRS-Institut Armand-Frappier F. LÉPINE, INRS-Institut Armand-Frappier R. VILLEMUR, INRS-Institut Armand-Frappier
Title
Proteomic Study of Desulfitobacterium frappieri PCP-1 Induced by 3,5-Dichlorophenol.
Abstract Text
Desulfitobacterium frappieri PCP-1 dechlorinates pentachlorophenol at the ortho, meta and para positions. It also dechlorinates various chlorobenzenes substituted with hydroxyl or amino groups. Two distinct reductive dehalogenases (I and II) are involved; the dehalogenase I performs ortho-dechlorination and the dehalogenase II dechlorinates at the meta and para positions. The purified dehalogenase II was characterized by mass spectrometry and a proteomic approach was used to study the induced and repressed proteins of the cytoplasmic and membranous fractions from PCP-1 cells grown with or without 3,5-dichlorophenol (3,5-DCP). Six induced and six repressed proteins were detected in 2-dimensional electrophoresis from cells cultured in presence of 3,5-DCP. The proteins were digested with trypsin, and the resulting peptides were sequenced by mass spectrometry. These sequences were compared to those of protein data bases. Open reading frames were found for four of the induced proteins in the Desulfitobacterium hafniense genome. One induced protein (58 kDa) was the dehalogenase II which shows a high similarity with a putative reductive dehalogenase encoded by a gene named rdA1. The second protein (53 kDa) shares 85 % identity with the large subunit of a putative Ni/Fe hydrogenase precursor. The third one (42.5 kDa) shares 58 % similarity with a putative electron transport protein and the fourth protein (62 kDa) shares 66% similarity with an uroporphyrinogen III synthase/methyltransferase. One repressed protein (42 kDa) shows 73% similarity with the NAD binding domain of a 2-hydroxyacid dehydrogenase. This work is important to understand the reductive dehalogenation by Desulfitobacterium frappieri.
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