Interplay of the modified nucleotide phosphoadenosine 5'-phosphosulfate (PAPS) with global regulatory proteins in Escherichia coli: modulation of cyclic AMP (cAMP)-dependent gene expression and interaction with the HupA regulatory protein.
In the bacterium Escherichia coli, some intermediates of the sulfate assimilation and cysteine biosynthesis pathway can act as signal molecules and modulate gene expression. In addition to sensing and utilization of sulphur sources, these signaling mechanisms also impact more global cell processes, such as resistance to antimicrobial agents and biofilm formation. In a recent work, we have shown that inactivation of the cysH gene, encoding phosphoadenosine-phosphosulfate (PAPS) reductase, and the consequent increase in intracellular PAPS concentration, strongly affect production of several cell surface-associated structures, enhancing surface adhesion and cell aggregation. In order to identify the molecular mechanism relaying intracellular PAPS concentration to regulation of cell surface-associated structures, we looked for mutations able to suppress the effects of cysH inactivation. We found that mutations in the adenylate cyclase-encoding cyaA gene abolished the effects of PAPS accumulation; consistent with this result, cyclic AMP (cAMP)-dependent gene expression appears to be increased in the cysH mutant. Experiments aimed at the direct identification of proteins interacting with either CysC or CysH, i.e. the PAPS-related proteins APS kinase and PAPS reductase, allowed us to identify several regulators, namely, CspC, CspE, HNS and HupA. Protein-protein interaction between HupA and CysH was confirmed by a bacterial two hybrid system, and inactivation of the hupA gene enhanced the effects of the cysH mutation in terms of production of cell surface-associated factors. Our results indicate that PAPS can modulate different regulatory systems, providing evidence that this molecule acts as a global signal molecule in E. coli.
Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy. Electronic address: francesca.longo@unimi.it.
Francesca
F
Longo
Institute of Biomedical Technologies, National Research Council, Via Fratelli Cervi 93, 20090, Segrate, Milan, Italy. Electronic address: sara.motta@itb.cnr.it.
Sara
S
Motta
Institute of Biomedical Technologies, National Research Council, Via Fratelli Cervi 93, 20090, Segrate, Milan, Italy. Electronic address: pierluigi.mauri@itb.cnr.it.
Pierluigi
P
Mauri
Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy. Electronic address: paolo.landini@unimi.it.
Paolo
P
Landini
Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133, Milan, Italy. Electronic address: elioros@biosustain.dtu.dk.
Elio
E
Rossi
D001426:Bacterial Proteins / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D009154:Mutation; D010724:Phosphoadenosine Phosphosulfate / Q000378:metabolism*; D015398:Signal Transduction
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C490937:hupA protein, E coli; D010724:Phosphoadenosine Phosphosulfate; D000242:Cyclic AMP; D003545:Cysteine
Adenylate cyclase CyaA; Cyclic adenosine monophosphate (cAMP); Gene expression regulation; Histone-like HU protein; Phosphoadenosine 5′-phosphosulphate (PAPS); Signal molecule