Transcriptomic and proteomic characterization of the Fur modulon in the metal-reducing bacterium Shewanella oneidensis.
The availability of the complete genome sequence for Shewanella oneidensis MR-1 has permitted a comprehensive characterization of the ferric uptake regulator (Fur) modulon in this dissimilatory metal-reducing bacterium. We have employed targeted gene mutagenesis, DNA microarrays, proteomic analysis using liquid chromatography-mass spectrometry, and computational motif discovery tools to define the S. oneidensis Fur regulon. Using this integrated approach, we identified nine probable operons (containing 24 genes) and 15 individual open reading frames (ORFs), either with unknown functions or encoding products annotated as transport or binding proteins, that are predicted to be direct targets of Fur-mediated repression. This study suggested, for the first time, possible roles for four operons and eight ORFs with unknown functions in iron metabolism or iron transport-related functions. Proteomic analysis clearly identified a number of transporters, binding proteins, and receptors related to iron uptake that were up-regulated in response to a fur deletion and verified the expression of nine genes originally annotated as pseudogenes. Comparison of the transcriptome and proteome data revealed strong correlation for genes shown to be undergoing large changes at the transcript level. A number of genes encoding components of the electron transport system were also differentially expressed in a fur deletion mutant. The gene omcA (SO1779), which encodes a decaheme cytochrome c, exhibited significant decreases in both mRNA and protein abundance in the fur mutant and possessed a strong candidate Fur-binding site in its upstream region, thus suggesting that omcA may be a direct target of Fur activation.
Wan
Xiu-Feng
XF
Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6038, USA.
Verberkmoes
Nathan C
NC
McCue
Lee Ann
LA
Stanek
Dawn
D
Connelly
Heather
H
Hauser
Loren J
LJ
Wu
Liyou
L
Liu
Xueduan
X
Yan
Tingfen
T
Leaphart
Adam
A
Hettich
Robert L
RL
Zhou
Jizhong
J
Thompson
Dorothea K
DK
D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D019295:Computational Biology / Q000379:methods; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010084:Oxidation-Reduction; D020543:Proteome; D018085:Regulon; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020592:Shewanella / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D020543:Proteome; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron