title: Cysteine desulphurase-encoding gene sufS2 is required for the repressor function of RirA and oxidative resistance in Agrobacterium tumefaciens.
abstract: The Agrobacterium tumefaciens genome contains a cluster of genes that are predicted to encode Fe-S cluster assembly proteins, and this cluster is known as the sufS2BCDS1XA operon. sufS2 is the first gene in the operon, and it was inactivated to determine its physiological function. The sufS2 mutant exhibited a small colony phenotype, grew slower than the wild-type strain and was more sensitive to various oxidants including peroxide, organic hydroperoxide and superoxide. The sufS2 gene was negatively regulated by iron response regulator (Irr) and rhizobial iron regulator (RirA) under low and high iron conditions, respectively, and was inducible in response to oxidative stress. The oxidant-induced expression of sufS2 was controlled by Irr, RirA and an additional but not yet identified mechanism. sufS2 was required for RirA activity in the repression of a sufS2 promoter-lacZ fusion. RirA may use Fe-S as its cofactor. sufS2 disruption may cause a defect in the Fe-S supply and could thereby affect the RirA activity. The three conserved cysteine residues (C91, C99 and C105) in RirA were predicted to coordinate with the Fe-S cluster and were shown to be essential for RirA repression of the sufS2-lacZ fusion. These results suggested that sufS2 is important for the survival of A. tumefaciens.
authors.affiliation: Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.|Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand.
authors.forename: Sakkarin
authors.initials: S
authors.lastname: Bhubhanil
authors.affiliation: Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.|Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand.
authors.forename: Phettree
authors.initials: P
authors.lastname: Niamyim
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.|Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.|Applied Biological Sciences, Chulabhorn Graduate Institute, Lak Si, Bangkok 10210, Thailand.
authors.forename: Rojana
authors.initials: R
authors.lastname: Sukchawalit
authors.affiliation: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.|Laboratory of Biotechnology, Chulabhorn Research Institute, Lak Si, Bangkok 10210, Thailand.|Center of Excellence on Environmental Health and Toxicology (EHT), Ministry of Education, Bangkok, Thailand.
authors.forename: Skorn
authors.initials: S
authors.lastname: Mongkolsuk
mesh_terms: D016960:Agrobacterium tumefaciens / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000502:physiology; D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000378:metabolism*; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D017930:Genes, Reporter; D050296:Microbial Viability; D016877:Oxidants / Q000633:toxicity; D018384:Oxidative Stress; D012097:Repressor Proteins / Q000378:metabolism*; D013312:Stress, Physiological; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D016877:Oxidants; D012097:Repressor Proteins; D001616:beta-Galactosidase; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase