title: Overlapping protective roles for glutathione transferase gene family members in chemical and oxidative stress response in Agrobacterium tumefaciens.
abstract: In the present work, we describe the characterisation of the glutathione transferase (GST) gene family from Agrobacterium tumefaciens C58. A genome survey revealed the presence of eight GST-like proteins in A. tumefaciens (AtuGSTs). Comparison by multiple sequence alignment generated a dendrogram revealing the phylogenetic relationships of AtuGSTs-like proteins. The beta and theta classes identified in other bacterial species are represented by five members in A. tumefaciens C58. In addition, there are three "orphan" sequences that do not fit into any previously recognised GST classes. The eight GST-like genes were cloned, expressed in Escherichia coli and their substrate specificity was determined towards 17 different substrates. The results showed that AtuGSTs catalyse a broad range of reactions, with different members of the family exhibiting quite varied substrate specificity. The 3D structures of AtuGSTs were predicted using molecular modelling. The use of comparative sequence and structural analysis of the AtuGST isoenzymes allowed us to identify local sequence and structural characteristics between different GST isoenzymes and classes. Gene expression profiling was conducted under normal culture conditions as well as under abiotic stress conditions (addition of xenobiotics, osmotic stress and cold and heat shock) to induce and monitor early stress-response mechanisms. The results reveal the constitutive expression of GSTs in A. tumefaciens and a modulation of GST activity after treatments, indicating that AtuGSTs presumably participate in a wide range of functions, many of which are important in counteracting stress conditions. These functions may be relevant to maintaining cellular homeostasis as well as in the direct detoxification of toxic compounds.
authors: Laboratory of Enzyme Technology, Department of Agricultural Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 11855 Athens, Greece.
authors: Katholiki
authors: K
authors: Skopelitou
authors: Abdi W
authors: AW
authors: Muleta
authors: Ourania
authors: O
authors: Pavli
authors: Georgios N
authors: GN
authors: Skaracis
authors: Emmanouil
authors: E
authors: Flemetakis
authors: Anastassios C
authors: AC
authors: Papageorgiou
authors: Nikolaos E
authors: NE
authors: Labrou
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology / Q000235:genetics* / Q000502:physiology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D010802:Phylogeny; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological / Q000187:drug effects; D040681:Structural Homology, Protein; D013379:Substrate Specificity; D014158:Transcription, Genetic; D015262:Xenobiotics / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D015262:Xenobiotics; D005982:Glutathione Transferase