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

Yang Y, Chen J, Qiu D, Zhou J - BMC Microbiol. (2013)

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

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. yangyf@tsinghua.edu.cn.

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.

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Sequence analysis of S.putrefaciens W3-18-1 UndA. (A) Schematic representation of the mtr-omc gene cluster in the genomes of selected Shewanella species. (B) The phylogenetic distance of UndA, MtrF, MtrG and MtrA protein sequences within sequenced Shewanella. The arrow points to the location of S. putrefaciens W3-18-1 UndA in the phylogenetic tree.
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Figure 2: Sequence analysis of S.putrefaciens W3-18-1 UndA. (A) Schematic representation of the mtr-omc gene cluster in the genomes of selected Shewanella species. (B) The phylogenetic distance of UndA, MtrF, MtrG and MtrA protein sequences within sequenced Shewanella. The arrow points to the location of S. putrefaciens W3-18-1 UndA in the phylogenetic tree.

Mentions: All of the currently sequenced Shewanella genomes except Shewanella denitrificans contain an mtr-omc gene cluster that encodes several proteins predicted to be associated with metal reduction [13,28]. Among these, mtrBAC are omnipresent and conserved in the cluster (Figure 2A). For example, a Blastp search indicated that W3-18-1 and S. oneidensis MR-1 MtrC share 48% identity and 60% similarity. However, W3-18-1 significantly differs from MR-1 in that the fourth gene of the gene cluster, designated as undA in this study, has no predictable orthologs in most Shewanella species. In addition, S. oneidensis omcA and mtrDEF are absent from the W3-18-1 genome. When protein sequence of undA was compared to that of omcA or mtrF, the results showed that it was 30% identity and 40% similarity, and 25% identity and 37% similarity, respectively. Notably, the identity between undA and omcA are largely attributed to the N-terminus (1–55 amino acids), which might be implicated as a signal peptide.


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

Yang Y, Chen J, Qiu D, Zhou J - BMC Microbiol. (2013)

Sequence analysis of S.putrefaciens W3-18-1 UndA. (A) Schematic representation of the mtr-omc gene cluster in the genomes of selected Shewanella species. (B) The phylogenetic distance of UndA, MtrF, MtrG and MtrA protein sequences within sequenced Shewanella. The arrow points to the location of S. putrefaciens W3-18-1 UndA in the phylogenetic tree.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4222724&req=5

Figure 2: Sequence analysis of S.putrefaciens W3-18-1 UndA. (A) Schematic representation of the mtr-omc gene cluster in the genomes of selected Shewanella species. (B) The phylogenetic distance of UndA, MtrF, MtrG and MtrA protein sequences within sequenced Shewanella. The arrow points to the location of S. putrefaciens W3-18-1 UndA in the phylogenetic tree.
Mentions: All of the currently sequenced Shewanella genomes except Shewanella denitrificans contain an mtr-omc gene cluster that encodes several proteins predicted to be associated with metal reduction [13,28]. Among these, mtrBAC are omnipresent and conserved in the cluster (Figure 2A). For example, a Blastp search indicated that W3-18-1 and S. oneidensis MR-1 MtrC share 48% identity and 60% similarity. However, W3-18-1 significantly differs from MR-1 in that the fourth gene of the gene cluster, designated as undA in this study, has no predictable orthologs in most Shewanella species. In addition, S. oneidensis omcA and mtrDEF are absent from the W3-18-1 genome. When protein sequence of undA was compared to that of omcA or mtrF, the results showed that it was 30% identity and 40% similarity, and 25% identity and 37% similarity, respectively. Notably, the identity between undA and omcA are largely attributed to the N-terminus (1–55 amino acids), which might be implicated as a signal peptide.

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

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China. yangyf@tsinghua.edu.cn.

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.

Show MeSH
Related in: MedlinePlus