DAO 106:129-138 (2013)  -  DOI: https://doi.org/10.3354/dao02635

Identification of an iron acquisition machinery in Flavobacterium columnare 

Lingyu Guan1,2,*, Javier Santander1,3,4,*, Melha Mellata1, Yuangxing Zhang2, Roy Curtiss 3rd1,3,**

1The Biodesign Institute, Arizona State University, Tempe, Arizona 85287, USA
2State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, P R China
3School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA
4Present address: Center for Genomics and Bioinformatics, Nucleus for Interdisciplinary Biotechnology, Universidad Mayor, Chile
*Contributed equally to this work.
**Corresponding author. Email:

ABSTRACT: Flavobacterium columnare, a fastidious Gram-negative pathogen and the causative agent of columnaris disease, is one of the most harmful pathogens in the freshwater fish-farming industry. Nevertheless the virulence mechanisms of F. columnare are not well understood. Bacterial iron uptake from the host during infection is an important mechanism of virulence. Here we identified and analyzed part of the iron uptake machinery of F. columnare. Under iron-limited conditions during in vitro growth, synthesis of an outer membrane protein of ~86 kDa was upregulated. This protein was identified as a TonB-dependent ferrichrome-iron receptor precursor (FhuA). Synthesis of siderophores in F. columnare was corroborated by chrome azurol S assays. A putative ferric uptake regulator (Fur) protein was also identified in the F. columnare genome. Structural analysis of the F. columnare Fur protein revealed that it was similar to Fur proteins involved in iron uptake regulation of other bacteria. Furthermore, Salmonella enterica serovar Typhimurium (S. Typhimurium) Δfur mutants were partially complemented by the F. columnare fur gene. We conclude that a siderophore-mediated iron uptake system exists in F. columnare, and fur from F. columnare could partially complement S. Typhimurium Δfur mutant.


KEY WORDS: Flavobacterium columnare · Siderophore · FhuA · Fur · Iron uptake


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Cite this article as: Guan L, Santander J, Mellata M, Zhang Y, Curtiss R 3rd (2013) Identification of an iron acquisition machinery in Flavobacterium columnare . Dis Aquat Org 106:129-138. https://doi.org/10.3354/dao02635

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