Functional Analysis of the Early Chlorosis Factor Gene

Morales, Christine Q; Posada, James; Macneale, E.; Franklin, Darleen; Rivas, Isabel; Bravo, Mayra; Minsavage, J.; Stall, Robert E.; Whalen, Maureen C.

doi:10.1094/mpmi-18-0477

Cited by 24 publications

(14 citation statements)

References 48 publications

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“…For five type III effector genes (xopB, xopC, xopD, xopJ, and xopQ), HrpX-dependent expression has now been confirmed experimentally (30-32; this study). Surprisingly, avrRxv and ecf were not upregulated in hrp-inducing minimal medium, although they contain candidate PIP box-regulated promoters (6,27). One explanation might be that the predicted promoters are not functional, as indicated by their exceptionally short or long distance to the predicted translational start codons.…”

Section: Discussionmentioning

confidence: 92%

Specific Binding of the Xanthomonas campestris pv. vesicatoria AraC-Type Transcriptional Activator HrpX to Plant-Inducible Promoter Boxes

et al. 2006

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The pathogenicity of the plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria depends on a type III secretion system which is encoded by the 23-kb hrp (hypersensitive response and pathogenicity) gene cluster. Expression of the hrp operons is strongly induced in planta and in a special minimal medium and depends on two regulatory proteins, HrpG and HrpX. In this study, DNA affinity enrichment was used to demonstrate that the AraC-type transcriptional activator HrpX binds to a conserved cis-regulatory element, the plant-inducible promoter (

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Section: Discussionmentioning

confidence: 92%

Specific Binding of the Xanthomonas campestris pv. vesicatoria AraC-Type Transcriptional Activator HrpX to Plant-Inducible Promoter Boxes

et al. 2006

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“…Oligonucleotide primers used for quantitative-PCR amplification will be provided upon request. As a control for real-time PCR, we used the 16S rRNA as described [113]. The 16S rRNA forward primer (5′-TGACGGTACCCAAAGAATAAGCA-3′) and 16S rRNA reverse primer (5′-ACGCTTGCACCCTTCGTATTA-3′) amplicon was 72 bp in length.…”

Section: Methodsmentioning

confidence: 99%

Plant Carbohydrate Scavenging through TonB-Dependent Receptors: A Feature Shared by Phytopathogenic and Aquatic Bacteria

et al. 2007

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TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other CUT loci involved in the utilization of various plant carbohydrates. Interestingly, several Xcc TBDRs and CUT loci are conserved in aquatic bacteria such as Caulobacter crescentus, Colwellia psychrerythraea, Saccharophagus degradans, Shewanella spp., Sphingomonas spp. or Pseudoalteromonas spp., which share the ability to degrade a wide variety of complex carbohydrates and display TBDR overrepresentation. We therefore propose that TBDR overrepresentation and the presence of CUT loci designate the ability to scavenge carbohydrates. Thus CUT loci, which seem to participate to the adaptation of phytopathogenic bacteria to their host plants, might also play a very important role in the biogeochemical cycling of plant-derived nutrients in marine environments. Moreover, the TBDRs and CUT loci identified in this study are clearly different from those characterized in the human gut symbiont Bacteroides thetaiotaomicron, which allow glycan foraging, suggesting a convergent evolution of TBDRs in Proteobacteria and Bacteroidetes.

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“…Oligonucleotide primers used for quantitative PCR amplification will be provided upon request. 16S rRNA was used as a control for real-time PCR (7,32).…”

Section: Methodsmentioning

confidence: 99%

Identification and Regulation of the N -Acetylglucosamine Utilization Pathway of the Plant Pathogenic Bacterium Xanthomonas campestris pv. campestris

et al. 2010

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Xanthomonas campestris pv. campestris, the causal agent of black rot disease of brassicas, is known for its ability to catabolize a wide range of plant compounds. This ability is correlated with the presence of specific carbohydrate utilization loci containing TonB-dependent transporters (CUT loci) devoted to scavenging specific carbohydrates. In this study, we demonstrate that there is an X. campestris pv. campestris CUT system involved in the import and catabolism of N-acetylglucosamine (GlcNAc). Expression of genes belonging to this GlcNAc CUT system is under the control of GlcNAc via the LacI family NagR and GntR family NagQ regulators. Analysis of the NagR and NagQ regulons confirmed that GlcNAc utilization involves NagA and NagB-II enzymes responsible for the conversion of GlcNAc-6-phosphate to fructose-6-phosphate. Mutants with mutations in the corresponding genes are sensitive to GlcNAc, as previously reported for Escherichia coli. This GlcNAc sensitivity and analysis of the NagQ and NagR regulons were used to dissect the X. campestris pv. campestris GlcNAc utilization pathway. This analysis revealed specific features, including the fact that uptake of GlcNAc through the inner membrane occurs via a major facilitator superfamily transporter and the fact that this amino sugar is phosphorylated by two proteins belonging to the glucokinase family, NagK-IIA and NagK-IIB. However, NagK-IIA seems to play a more important role in GlcNAc utilization than NagK-IIB under our experimental conditions. The X. campestris pv. campestris GlcNAc NagR regulon includes four genes encoding TonB-dependent active transporters (TBDTs). However, the results of transport experiments suggest that GlcNAc passively diffuses through the bacterial envelope, an observation that calls into question whether GlcNAc is a natural substrate for these TBDTs and consequently is the source of GlcNAc for this nonchitinolytic plant-associated bacterium.

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Functional Analysis of the Early Chlorosis Factor Gene

Cited by 24 publications

References 48 publications

Specific Binding of the Xanthomonas campestris pv. vesicatoria AraC-Type Transcriptional Activator HrpX to Plant-Inducible Promoter Boxes

Specific Binding of the Xanthomonas campestris pv. vesicatoria AraC-Type Transcriptional Activator HrpX to Plant-Inducible Promoter Boxes

Plant Carbohydrate Scavenging through TonB-Dependent Receptors: A Feature Shared by Phytopathogenic and Aquatic Bacteria

Identification and Regulation of the N -Acetylglucosamine Utilization Pathway of the Plant Pathogenic Bacterium Xanthomonas campestris pv. campestris

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