title: Sulfate assimilation pathway intermediate  phosphoadenosine 59-phosphosulfate acts as a  signal molecule affecting production of curli fibres  in Escherichia coli.
abstract: The enterobacterium Escherichia coli can utilize a variety of molecules as sulfur sources, including cysteine, sulfate, thiosulfate and organosulfonates. An intermediate of the sulfate assimilation pathway, adenosine 59-phosphosulfate (APS), also acts as a signal molecule regulating the utilization of different sulfur sources. In this work, we show that inactivation of the cysH gene, leading to accumulation of phosphoadenosine 59-phosphosulfate (PAPS), also an intermediate of the sulfate assimilation pathway, results in increased surface adhesion and cell aggregation by activating the expression of the curli-encoding csgBAC operon. In contrast, curli production was unaffected by the inactivation of any other gene belonging to the sulfate assimilation pathway. Overexpression of the cysH gene downregulated csgBAC transcription, further suggesting a link between intracellular PAPS levels and curli gene expression. In addition to curli components, the Flu, OmpX and Slp proteins were also found in increased amounts in the outer membrane compartment of the cysH mutant; deletion of the corresponding genes suggested that these proteins also contribute to surface adhesion and cell surface properties in this strain. Our results indicate that, similar to APS, PAPS also acts as a signal molecule, albeit with a distinct mechanism and role: whilst APS regulates organosulfonate utilization, PAPS would couple availability of sulfur sources to remodulation of the cell surface, as part of a more global effect on cell physiology.
authors.affiliation: Department of Biosciences, Università degli Studi di Milano, Via Celoria, 26, 20133 Milan, Italy.
authors.forename: Elio
authors.initials: E
authors.lastname: Rossi
authors.affiliation: Institute of Biomedical Technologies, National Research Council, Via Fratelli Cervi 93, 20090 Segrate, Milan, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Motta
authors.affiliation: Institute of Biomedical Technologies, National Research Council, Via Fratelli Cervi 93, 20090 Segrate, Milan, Italy.
authors.forename: Pierluigi
authors.initials: P
authors.lastname: Mauri
authors.affiliation: Department of Biosciences, Università degli Studi di Milano, Via Celoria, 26, 20133 Milan, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Landini
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010724:Phosphoadenosine Phosphosulfate / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C109182:CsgB protein, E coli; C556817:CsgC protein, E coli; D029968:Escherichia coli Proteins; C489688:csgA protein, E coli; C077481:Crl protein, Bacteria; D010724:Phosphoadenosine Phosphosulfate; D010088:Oxidoreductases; C052449:3'-phosphoadenylyl-5'-phosphosulfate reductase