title: Proteomic characterization of a pilR regulatory mutant of Azoarcus sp. strain BH72 with the aid of gel-based and gel-free approaches.
abstract: The proteome of the grass endophyte Azoarcus sp. strain BH72 was analyzed by a combination of gel-based methods by means of 2-DE and MS and a gel-free approach via LC-MS/MS. Among the identified 785 proteins, synthesis of around 100 conserved hypothetical proteins could be confirmed. Membrane proteins were detected at a higher rate in the gel-free than in the gel-based approach. The abundance of proteins in the constructed proteome reference map was analyzed and the 30 most abundant proteins were determined. The reference map was then used as a starting point to characterize the regulon under control of the response regulator PilR. PilR is part of the two-component regulatory system PilSR controlling type IV pilin gene (pilAB) expression in strain BH72, which was strongly decreased (19.7-fold) in the pilR-mutant. Changes of protein composition in the wild type and the regulatory mutant were compared by the gel-based and gel-free analyses. Proteins responsible for amino acid and energy metabolism, chaperones as well as proteins that are involved in iron metabolism and iron storage were present in a pilR-mutant at different levels than in the wild-type strain. Levels of the transcriptional regulator Flp were also dependent on PilR, indicating that PilR might be part of a hierarchical regulatory cascade.
authors.affiliation: Laboratory for General Microbiology, University Bremen, Bremen, Germany.
authors.forename: Lena
authors.initials: L
authors.lastname: Hauberg
authors.forename: Frank
authors.initials: F
authors.lastname: Schmidt
authors.forename: Christian
authors.initials: C
authors.lastname: Scharf
authors.forename: Juliane
authors.initials: J
authors.lastname: Dörr
authors.forename: Uwe
authors.initials: U
authors.lastname: Völker
authors.forename: Barbara
authors.initials: B
authors.lastname: Reinhold-Hurek
mesh_terms: D020627:Azoarcus / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D009154:Mutation; D051922:PII Nitrogen Regulatory Proteins / Q000378:metabolism*; D020543:Proteome / Q000235:genetics*; D040901:Proteomics / Q000379:methods
chemical_list: D051922:PII Nitrogen Regulatory Proteins; D020543:Proteome