SO2907, A Putative TonB-dependent Receptor, Is Involved in Dissimilatory Iron Reduction by Shewanella oneidensis Strain MR-1
Shewanella oneidensis strain MR-1 utilizes soluble and insoluble ferric ions as terminal electron acceptors during anaerobic respiration. The components of respiratory metabolism are localized in the membrane fractions which include the outer membrane and cytoplasmic membrane. Many of the biological components that interact with the various iron forms are proposed to be localized in these membrane fractions. To identify the iron-binding proteins acting either as an iron transporter or as a terminal iron reductase, we used metal-catalyzed oxidation reactions. This system catalyzed the oxidation of amino acids in close proximity to the iron binding site. The carbonyl groups formed from this oxidation can then be labeled with fluoresceinamine (FLNH2). The peptide harboring the FLNH2 can then be proteolytically digested, purified by HPLC and then identified by MALDI-TOF tandem MS. A predominant peptide was identified to be part of SO2907 that encodes a putative TonB-dependent receptor. Compared to wild type (wt), the so2097 gene deletion (ΔSO2907) mutant has impaired ability to reduce soluble Fe(III), but retains the same ability to respire oxygen or fumarate as the wt. The ΔSO2907 mutant was also impacted in reduction of insoluble iron. Iron binding assays using isothermal titration calorimetry and fluorescence tryptophan quenching demonstrated that a truncated form of heterologous-expressed SO2907 that contains the Fe(III) binding site, is capable of binding soluble Fe(III) forms with Kd of approximate 50 μM. To the best of our knowledge, this is the first report of the physiological role of SO2907 in Fe(III) reduction by MR-1.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1026604
- Report Number(s):
- PNNL-SA-82364; JBCHA3; KP1702030; TRN: US201120%%933
- Journal Information:
- Journal of Biological Chemistry, 286(39):33973-33980, Vol. 286, Issue 39; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
Similar Records
Role of Outer-Membrane Cytochromes MtrC and OmcA in the Biomineralization of Ferrihydrite by Shewanella oneidensis MR-1.
Isolation of a High-Affinity Functional Protein Complex between OmcA and MtrC: Two Outer Membrane Decaheme c-type Cytochromes of Shewanella oneidensis MR-1
Related Subjects
60 APPLIED LIFE SCIENCES
AMINO ACIDS
BACTERIA
BINDING ENERGY
CALORIMETRY
CARBONYLS
ELECTRONS
FLUORESCENCE
GENES
HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY
IRON
IRON IONS
MEMBRANES
METABOLISM
MUTANTS
OXIDATION
OXYGEN
PEPTIDES
PROTEINS
QUENCHING
RESPIRATION
STRAINS
TITRATION
TRYPTOPHAN
VALENCE