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Pb+2 Tolerance by Frankia sp. strain EAN1pec Involves Surface-Binding
- Authors: Teal Furnholm1, Medhat Rehan2, Jessica Wishart3, Louis S. Tisa4
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1 1Department of Cellular. Molecular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA 2 2Department of Genetics, College of Agriculture, Kafrelsheikh University, Egypt 3 3Department of Cellular. Molecular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA 4 4University of New Hampshire
- First Published Online: 28 January 2017, Microbiology doi: 10.1099/mic.0.000439
- Issue Published:
Several Frankia strains have been shown to be lead-resistant. The mechanism of lead resistance was investigated for Frankia sp. strain EAN1pec. Analysis of the cultures by SEM, EDAX, and FTIR demonstrated that Frankia sp. strain EAN1pec undergoes surface modifications and binds high quantities of Pb2+. Both labeled and un-labeled shotgun proteomics approaches were used to determine changes in Frankia sp. strain EAN1pec protein expression in response to lead and zinc. Pb2+ specifically induced changes in exopolysaccharides, the stringent response, and the phosphate (pho) regulon. Two metal transporters (a Cu2+-ATPase and cation diffusion facilitator), as well as several hypothetical transporters, were also up-regulated and may be involved in metal export. The exported Pb2+ may be precipitated at the cell surface by an up-regulated polyphosphate kinase, undecaprenyl diphosphate synthase and inorganic diphosphatase. A variety of metal chaperones for ensuring correct cofactor placement were also up-regulated with both Pb2+ and Zn2+ stress. Thus, this Pb2+ resistance mechanism is similar to other characterized systems. The cumulative interplay of these many mechanisms may explain the extraordinary resilience of Frankia sp. strain EAN1pec to Pb2+. A potential transcription factor (DUF156) binding site was identified in association with several proteins identified as up-regulated with heavy metals. This site was also discovered, for the first time, in thousands of other organisms across two kingdoms.
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/content/journal/micro/10.1099/mic.0.000439.v1dcterms_title-pub_serialIdent:journal/ AND -contentType:BlogPost104
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