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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Diffusible Signal Factor (DSF) Synthase RpfF of Xylella fastidiosa Is a Multifunction Protein Also Required for Response to DSF

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Author(s):
Ionescu, Michael [1] ; Baccari, Clelia [1] ; Da Silva, Aline Maria [2] ; Garcia, Angelica [1] ; Yokota, Kenji [3] ; Lindow, Steven E. [1]
Total Authors: 6
Affiliation:
[1] Univ Calif Berkeley, Dept Plant & Microbial Biol, Berkeley, CA 94720 - USA
[2] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-01498 Sao Paulo - Brazil
[3] Tokyo Univ Agr, Dept Appl Biol & Chem, Tokyo - Japan
Total Affiliations: 3
Document type: Journal article
Source: Journal of Bacteriology; v. 195, n. 23, p. 5273-5284, DEC 2013.
Web of Science Citations: 24
Abstract

Xylella fastidiosa, like related Xanthomonas species, employs an Rpf cell-cell communication system consisting of a diffusible signal factor (DSF) synthase, RpfF, and a DSF sensor, RpfC, to coordinate expression of virulence genes. While phenotypes of a Delta rpfF strain in Xanthomonas campestris could be complemented by its own DSF, the DSF produced by X. fastidiosa (XfDSF) did not restore expression of the XfDSF-dependent genes hxfA and hxfB to a Delta rpfF strain of X. fastidiosa, suggesting that RpfF is involved in XfDSF sensing or XfDSF-dependent signaling. To test this conjecture, rpfC and rpfF of X. campestris were replaced by those of X. fastidiosa, and the contribution of each gene to the induction of a X. campestris DSF-dependent gene was assessed. As in X. fastidiosa, XfDSF-dependent signaling required both X. fastidiosa proteins RpfF and RpfC. RpfF repressed RpfC signaling activity, which in turn was derepressed by XfDSF. A mutated X. fastidiosa RpfF protein with two substitutions of glutamate to alanine in its active site was incapable of XfDSF production yet enabled a response to XfDSF, indicating that XfDSF production and the response to XfDSF are two separate functions in which RpfF is involved. This mutant was also hypervirulent to grape, demonstrating the antivirulence effects of XfDSF itself in X. fastidiosa. The Rpf system of X. fastidiosa is thus a novel example of a quorum-sensing signal synthase that is also involved in the response to the signal molecule that it synthesizes. (AU)

FAPESP's process: 10/16409-7 - Molecular aspects of Xylella fastidiosa-plant interaction
Grantee:Aline Maria da Silva
Support Opportunities: Scholarships abroad - Research