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Title: Identification and Characterization of UndA-HRCR-6, an Outer Membrane Endecaheme c-Type Cytochrome of Shewanella sp. Strain HRCR-6

The outer membrane decaheme c-type cytochromes (c-Cyt) MtrC and OmcA of Shewanella oneidensis MR-1(MR-1) play critical roles in extracellular reduction of iron [Fe(III)] oxides and uranium [ U(VI)]. To identify and characterize the outer membrane c-Cyts found in the metal-reducing Shewanella strains isolated from the Hanford Reach of the Columbia River (HRCR), 7 HRCR isolates were tested for the presence of mtrC, omcA and undA1 (a gene encoding a putative 11-heme c-Cyt) homologues in their genomes. All 7 tested strains possessed an mtrC homologue, while 3 strains had an omcA homologue and the remaining 4 strains contained an undA1 homologue. The coding region of an undA1 homologue from HRCR isolate 6 was cloned and sequenced. Because it was 93% identical to the UndA of S. baltica OS223, the protein product encoded by this sequenced gene was named as UndA-HRCR6. In MR-1, UndA-HRCR6 (i) restored an MR-1 mutant’s ability to reduce solid phase ferrihydrite at 40% of that for MR-1 wild type, (ii) increased extracellular formation of UO2 associated with the outer membrane and extracellular polymeric substances in a U(VI) reduction assay and (iii) was secreted to the extracellular environment by bacterial type II secretion system. UndA-HRCR6 was purified from themore » membrane fraction following its overexpression in MR-1 cells. Purified UndA-HRCR6 possessed 11 heme-Fe and reduced ferric complexes. Collectively, these results show that UndA-HRCR6 is an outer membrane endecaheme c-Cyt and can serve an extracellular metal reductase with functions similar to that of MR-1 MtrC and OmcA.« less
Authors:
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Publication Date:
OSTI Identifier:
1023724
Report Number(s):
PNNL-SA-77918
Journal ID: ISSN 0099-2240; AEMIDF; 13994; KP1702030; TRN: US201120%%1060
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied and Environmental Microbiology, 77(15):5521-5523; Journal Volume: 77; Journal Issue: 15
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 54 ENVIRONMENTAL SCIENCES; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; BACTERIA; COLUMBIA RIVER; COMPLEXES; CYTOCHROMES; FUNCTIONS; GENES; IRON OXIDES; MEMBRANES; METALS; OXIDOREDUCTASES; PROTEINS; REDUCTION; SECRETION; SOLIDS; URANIUM Environmental Molecular Sciences Laboratory