title: Analysis of a Coxiella burnetti gene product that activates capsule synthesis in Escherichia coli: requirement for the heat shock chaperone DnaK and the two-component regulator RcsC.
abstract: A 1.2-kb EcoRI genomic DNA fragment of Coxiella burnetti, when cloned onto a multicopy plasmid, was found to induce capsule synthesis (mucoidy) in Escherichia coli. Nucleotide sequence analysis revealed the presence of an open reading frame that could encode a protein of 270 amino acids. Insertion of a tet cassette into a unique NruI restriction site resulted in the loss of induction of mucoidy. Because of its ability to induce mucoidy, we designated this gene mucZ. Computer search for homologies to mucZ revealed 42% identity to an open reading frame located at 1 min of the E. coli chromosome. Interestingly, the C-terminal amino acid residues of MucZ share significant homology with the J domain of the DnaJ protein and its homologs, suggesting potential interactions between MucZ and components of the DnaK-chaperone machinery. Results presented in this paper suggest that E. coli requires DnaK-chaperone machinery for Lon-RcsA-mediated induction of capsule synthesis, as noticed first by S. Gottesman (personal communication). The induction caused by MucZ is independent of Lon-RcsA and is mediated through the two-component regulators RcsC and RcsB. DnaK and GrpE but not DnaJ are also required for the RcsB-mediated MucZ induction, and we propose that MucZ is a DnaJ-like chaperone protein that might be required for the formation of an active RcsA-RcsB complex and for the RcsC-dependent phosphorylation of RcsB. Discussions are presented that suggest three different roles for alternative forms of the DnaK-chaperone machinery in capsule production.
authors.affiliation: Toxinology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702-5011, USA.
authors.forename: M
authors.initials: M
authors.lastname: Zuber
authors.forename: T A
authors.initials: TA
authors.lastname: Hoover
authors.forename: D L
authors.initials: DL
authors.lastname: Court
mesh_terms: D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000096:biosynthesis / Q000235:genetics; D000595:Amino Acid Sequence; D016667:Bacterial Capsules / Q000096:biosynthesis* / Q000235:genetics; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D016384:Consensus Sequence; D016997:Coxiella burnetii / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D010749:Phosphoprotein Phosphatases; D049070:Protease La; D011494:Protein Kinases; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; C068113:GrpE protein, Bacteria; C489400:GrpE protein, E coli; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; C095073:MucZ protein, Coxiella burnetti; D009097:Multienzyme Complexes; C489568:RcsB protein, E coli; D014157:Transcription Factors; C489728:rcsC protein, E coli; C074889:RcsB protein, Bacteria; C067572:RcsA protein, E coli; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La; D000251:Adenosine Triphosphatases; C063842:dnaK protein, E coli