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Proteomic Analysis of the GacA Response Regulator in Pseudomonas chlororaphis O6
Res. Plant Dis. 2018;24:162-169
Published online June 30, 2018
© 2018 The Korean Society of Plant Pathology.

Anne J. Anderson1 and Young Cheol Kim2*

1Department of Biological Engineering, Utah State University, Logan, UT 84322-4105, USA
2Department of Applied Biology, Chonnam National University, Gwangju 61186, Korea
Tel: +82-62-530-2071
Fax: +82-62-530-2079
Received June 3, 2018; Revised June 6, 2018; Accepted June 22, 2018.
cc This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
The GacS/GacA system in the root colonizer Pseudomonas chlororaphis O6 is a key regulatory system of many traits relevant to the plant probiotic nature of this bacterium. The work in this paper elucidates proteins using proteomics approach in P. chlororaphis O6 under the control of the cytoplasmic regulatory protein, GacA. A gacA mutant of P. chlororaphis O6 showed loss in production of phenazines, acyl homoserine lactones, hydrogen cyanide, and protease, changes that were associated with reduced in vitro antifungal activity against plant fungal pathogens. Production of iron-chelating siderophore was significantly enhanced in the gacA mutant, also paralleling changes in a gacS mutant. However, proteomic analysis revealed proteins (13 downregulated and 7 upregulated proteins in the mutant compared to parental strain) under GacA control that were not apparent by a proteomic study of a gacS mutant. The putative identity of the downregulated proteins suggested that a gacA mutant would have altered transport potentials. Notable would be a predicted loss of type-VI secretion and PEP-dependent transport. Study of mutants of these GacA-regulated proteins will indicate further the features required for probiotic potential in this rhizobacterium.
Keywords : GacA response regulator, Proteomic analysis, Type 6 secretion system, Siderophore

June 2018, 24 (2)