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Open Access Research article

Roles of UndA and MtrC of Shewanella putrefaciens W3-18-1 in iron reduction

Yunfeng Yang1*, Jingrong Chen2, Dongru Qiu23 and Jizhong Zhou124

Author Affiliations

1 State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China

2 Institute for Environmental Genomics and Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA

3 Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China

4 Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

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BMC Microbiology 2013, 13:267  doi:10.1186/1471-2180-13-267

Published: 25 November 2013

Abstract

Background

The completion of genome sequencing in a number of Shewanella species, which are most renowned for their metal reduction capacity, offers a basis for comparative studies. Previous work in Shewanella oneidensis MR-1 has indicated that some genes within a cluster (mtrBAC-omcA-mtrFED) were involved in iron reduction. To explore new features of iron reduction pathways, we experimentally analyzed Shewanella putrefaciens W3-18-1 since its gene cluster is considerably different from that of MR-1 in that the gene cluster encodes only four ORFs.

Results

Among the gene cluster, two genes (mtrC and undA) were shown to encode c-type cytochromes. The ΔmtrC deletion mutant revealed significant deficiencies in reducing metals of Fe2O3, α-FeO(OH), β-FeO(OH), ferric citrate, Mn(IV) and Co(III), but not organic compounds. In contrast, no deficiency of metal reduction was observed in the ΔundA deletion mutant. Nonetheless, undA deletion resulted in progressively slower iron reduction in the absence of mtrC and fitness loss under the iron-using condition, which was indicative of a functional role of UndA in iron reduction.

Conclusions

These results provide physiological and biochemical evidences that UndA and MtrC of Shewanella putrefaciens W3-18-1 are involved in iron reduction.

Keywords:
Shewanella putrefaciens W3-18-1; Iron reduction; c-type cytochrome