Promiscuous Diffusible Signal Factor Production and Responsiveness of the Xylella fastidiosa Rpf System

ABSTRACT Cell density-dependent regulation of gene expression in Xylella fastidiosa that is crucial to its switching between plant hosts and insect vectors is dependent on RpfF and its production of 2-enoic acids known as diffusible signal factor (DSF). We show that X. fastidiosa produces a particularly large variety of similar, relatively long-chain-length 2-enoic acids that are active in modulating gene expression. Both X. fastidiosa itself and a Pantoea agglomerans surrogate host harboring X. fastidiosa RpfF (XfRpfF) is capable of producing a variety of both saturated and unsaturated free fatty acids. However, only 2-cis unsaturated acids were found to be biologically active in X. fastidiosa. X. fastidiosa produces, and is particularly responsive to, a novel DSF species, 2-cis-hexadecanoic acid that we term XfDSF2. It is also responsive to other, even longer 2-enoic acids to which other taxa such as Xanthomonas campestris are unresponsive. The 2-enoic acids that are produced by X. fastidiosa are strongly affected by the cellular growth environment, with XfDSF2 not detected in culture media in which 2-tetradecenoic acid (XfDSF1) had previously been found. X. fastidiosa is responsive to much lower concentrations of XfDSF2 than XfDSF1. Apparently competitive interactions can occur between various saturated and unsaturated fatty acids that block the function of those agonistic 2-enoic fatty acids. By altering the particular 2-enoic acids produced and the relative balance of free enoic and saturated fatty acids, X. fastidiosa might modulate the extent of DSF-mediated quorum sensing. IMPORTANCE X. fastidiosa, having a complicated lifestyle in which it moves and multiplies within plants but also must be vectored by insects, utilizes DSF-based quorum sensing to partition the expression of traits needed for these two processes within different cells in this population based on local cellular density. The finding that it can produce a variety of DSF species in a strongly environmentally context-dependent manner provides insight into how it coordinates the many genes under the control of DSF signaling to successfully associate with its two hosts. Since the new DSF variant XfDSF2 described here is much more active than the previously recognized DSF species, it should contribute to plant disease control, given that the susceptibility of plants can be greatly reduced by artificially elevating the levels of DSF in plants, creating “pathogen confusion,” resulting in lower virulence. X. fastidiosa, having a complicated lifestyle in which it moves and multiplies within plants but also must be vectored by insects, utilizes DSF-based quorum sensing to partition the expression of traits needed for these two processes within different cells in this population based on local cellular density. The finding that it can produce a variety of DSF species in a strongly environmentally context-dependent manner provides insight into how it coordinates the many genes under the control of DSF signaling to successfully associate with its two hosts. Since the new DSF variant XfDSF2 described here is much more active than the previously recognized DSF species, it should contribute to plant disease control, given that the susceptibility of plants can be greatly reduced by artificially elevating the levels of DSF in plants, creating “pathogen confusion,” resulting in lower virulence.

[1]  Lian-Hui Zhang,et al.  Diffusible signal factor family signals provide a fitness advantage to Xanthomonas campestris pv. campestris in interspecies competition. , 2016, Environmental microbiology.

[2]  Lian Zhou,et al.  The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae. , 2016, Molecular plant-microbe interactions : MPMI.

[3]  L. Eberl,et al.  Evidence for the widespread production of DSF family signal molecules by members of the genus Burkholderia by the aid of novel biosensors. , 2016, Environmental microbiology reports.

[4]  Lian Zhou,et al.  Identification and characterization of naturally occurring DSF-family quorum sensing signal turnover system in the phytopathogen Xanthomonas. , 2015, Environmental microbiology.

[5]  Lian Zhou,et al.  The Multiple DSF-family QS Signals are Synthesized from Carbohydrate and Branched-chain Amino Acids via the FAS Elongation Cycle , 2015, Scientific Reports.

[6]  J. M. Dow,et al.  The DSF Family of Cell–Cell Signals: An Expanding Class of Bacterial Virulence Regulators , 2015, PLoS pathogens.

[7]  Lian-Hui Zhang,et al.  The Host Plant Metabolite Glucose Is the Precursor of Diffusible Signal Factor (DSF) Family Signals in Xanthomonas campestris , 2015, Applied and Environmental Microbiology.

[8]  S. Lindow,et al.  Xylella fastidiosa outer membrane vesicles modulate plant colonization by blocking attachment to surfaces , 2014, Proceedings of the National Academy of Sciences.

[9]  J. Cronan,et al.  Xanthomonas campestris RpfB is a fatty Acyl‐CoA ligase required to counteract the thioesterase activity of the RpfF diffusible signal factor (DSF) synthase , 2014, Molecular microbiology.

[10]  Karyn L. Newman,et al.  Production of Xylella fastidiosa diffusible signal factor in transgenic grape causes pathogen confusion and reduction in severity of Pierce's disease. , 2014, Molecular plant-microbe interactions : MPMI.

[11]  S. Lindow,et al.  Diffusible Signal Factor (DSF) Synthase RpfF of Xylella fastidiosa Is a Multifunction Protein Also Required for Response to DSF , 2013, Journal of bacteriology.

[12]  R. Tecon,et al.  Draft Genome Sequence of the Phyllosphere Model Bacterium Pantoea agglomerans 299R , 2013, Genome Announcements.

[13]  D. Trauner,et al.  Characterization of a Diffusible Signaling Factor from Xylella fastidiosa , 2013, mBio.

[14]  S. Lindow,et al.  RpfF-dependent regulon of Xylella fastidiosa. , 2012, Phytopathology.

[15]  Karyn L. Newman,et al.  Contribution of rpfB to cell-to-cell signal synthesis, virulence, and vector transmission of Xylella fastidiosa. , 2012, Molecular plant-microbe interactions : MPMI.

[16]  J. Cronan,et al.  The Burkholderia cenocepacia BDSF quorum sensing fatty acid is synthesized by a bifunctional crotonase homologue having both dehydratase and thioesterase activities , 2012, Molecular microbiology.

[17]  Lian-Hui Zhang,et al.  Listening to a new language: DSF-based quorum sensing in Gram-negative bacteria. , 2011, Chemical reviews.

[18]  Lian-Hui Zhang,et al.  Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production , 2010, BMC Microbiology.

[19]  L. Eberl,et al.  Structural and Functional Characterization of Diffusible Signal Factor Family Quorum-Sensing Signals Produced by Members of the Burkholderia cepacia Complex , 2010, Applied and Environmental Microbiology.

[20]  D. Davies,et al.  A Fatty Acid Messenger Is Responsible for Inducing Dispersion in Microbial Biofilms , 2008, Journal of bacteriology.

[21]  Karyn L. Newman,et al.  Cell-to-cell signaling in Xylella fastidiosa suppresses movement and xylem vessel colonization in grape. , 2008, Molecular plant-microbe interactions : MPMI.

[22]  S. Lindow,et al.  Living in two worlds: the plant and insect lifestyles of Xylella fastidiosa. , 2008, Annual review of phytopathology.

[23]  M. Roessle,et al.  Interaction of quorum signals with outer membrane lipids: insights into prokaryotic membrane vesicle formation , 2008, Molecular microbiology.

[24]  C. Schofield,et al.  Mechanisms and structures of crotonase superfamily enzymes – How nature controls enolate and oxyanion reactivity , 2008, Cellular and Molecular Life Sciences.

[25]  C. Rock,et al.  Membrane lipid homeostasis in bacteria , 2008, Nature Reviews Microbiology.

[26]  S. Lindow,et al.  A cell–cell signaling sensor is required for virulence and insect transmission of Xylella fastidiosa , 2008, Proceedings of the National Academy of Sciences.

[27]  Lian-Hui Zhang,et al.  A novel DSF-like signal from Burkholderia cenocepacia interferes with Candida albicans morphological transition , 2008, The ISME Journal.

[28]  Tzu-Pi Huang,et al.  Extracellular fatty acids facilitate flagella-independent translocation by Stenotrophomonas maltophilia. , 2007, Research in microbiology.

[29]  E. Carrilho,et al.  Characterization of a putative Xylella fastidiosa diffusible signal factor by HRGC-EI-MS. , 2007, Journal of mass spectrometry : JMS.

[30]  J. M. Dow,et al.  Cell-cell signaling in Xanthomonas campestris involves an HD-GYP domain protein that functions in cyclic di-GMP turnover. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[31]  J. M. Dow,et al.  Genome scale analysis of diffusible signal factor regulon in Xanthomonas campestris pv. campestris: identification of novel cell–cell communication‐dependent genes and functions , 2006, Molecular microbiology.

[32]  B. Kirkpatrick,et al.  Identification of Xylella fastidiosa Antivirulence Genes: Hemagglutinin Adhesins Contribute to X. fastidiosa Biofilm Maturation and Colonization and Attenuate Virulence , 2005 .

[33]  B. Kirkpatrick,et al.  Identification of Xylella fastidiosa antivirulence genes: hemagglutinin adhesins contribute a biofilm maturation to X. fastidios and colonization and attenuate virulence. , 2005, Molecular plant-microbe interactions : MPMI.

[34]  Karyn L. Newman,et al.  Cell-cell signaling controls Xylella fastidiosa interactions with both insects and plants. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[35]  Lian-Hui Zhang,et al.  A bacterial cell–cell communication signal with cross‐kingdom structural analogues , 2003, Molecular microbiology.

[36]  D. Hopkins,et al.  Xylella fastidiosa: Cause of Pierce's Disease of Grapevine and Other Emergent Diseases. , 2002, Plant disease.

[37]  J. M. Dow,et al.  A novel regulatory system required for pathogenicity of Xanthomonas campestris is mediated by a small diffusible signal molecule , 1997, Molecular microbiology.

[38]  S. Lindow,et al.  Characterization of the indole-3-acetic acid (IAA) biosynthetic pathway in an epiphytic strain of Erwinia herbicola and IAA production in vitro , 1996 .

[39]  D. Hopkins,et al.  Fastidious xylem-limited bacterial plant pathogens. , 1996, Annual review of phytopathology.

[40]  S. Lindow,et al.  A Biological Sensor for Iron Available to Bacteria in Their Habitats on Plant Surfaces , 1994, Applied and environmental microbiology.

[41]  M. P. Starr,et al.  The Prokaryotes : a handbook on habitats, isolation, and identification of bacteria , 1981 .

[42]  A. Torriani.  The Alkaline Phosphatase of Escherichia coli , 1974 .

[43]  King Eo,et al.  Two simple media for the demonstration of pyocyanin and fluorescin. , 1954 .

[44]  E. King,et al.  Two simple media for the demonstration of pyocyanin and fluorescin. , 1954, The Journal of laboratory and clinical medicine.