Bacteriophytochromes control conjugation in Agrobacterium fabrum

Bai, Yanling; Rottwinkel, Gregor; Feng, Jia‐Xun; Liu, Yiyao; Lamparter, Tilman

doi:10.1016/j.jphotobiol.2016.05.014

Cited by 33 publications

(42 citation statements)

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“…All strains except one contain an Agp2 homolog, whereas only four (including Agrobacterium fabrum C58) contain an Agp1 homolog, and there was no Agrobacterium species without a phytochrome ( Figure 1 ), suggesting that all strains can respond to light. Agp2 of A. fabrum and related phytochromes from Rhizobiaceae (15, 24, 25) belong to the bathy phytochromes which have a Pfr dark state and absorb maximally in the 750 nm wavelength range. Since among the Agp2 homologs in the Agrobacterium strains, all amino acids in the chromophore pocket (26) are conserved, we predict that these are all bathy phytochromes.…”

Section: Resultsmentioning

confidence: 99%

“…In earlier work we found no effect of phytochromes on A. fabrum growth during 6 h (13). In the present study, we expanded the growth period to 51 h and performed assays at different temperatures, because Agp1 might also function as a thermosensor (15, 24, 27). Up to cultivation times of 6 h, the growth at ambient temperature was again not significantly different between wild type and mutants, but during prolonged growth times, all three knockout mutants displayed faster growth than the wild type ( Figure 2A-B ).…”

Section: Resultsmentioning

confidence: 99%

“…In a search for phytochrome responses of A. fabrum , however, knockout mutants were generated which had no apparent phenotype (13). A first clear Agrobacterium phytochrome response was found by a codistribution study (14, 15). In this investigation, Agp1 and Agp2 BLAST homologs were found in an almost identical subset of Rhizobiales species as BLAST homologs of TraA, a central player in bacterial conjugation.…”

Section: Introductionmentioning

confidence: 99%

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Phytochrome mediated responses inAgrobacterium fabrum: growth, swimming, plant infection and interbacterial competition

Xue

Bai

Rottwinkel

et al. 2020

Preprint

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The soil bacterium Agrobacterium fabrum C58 infects plants by a unique 15 DNA transfer mechanism. A. fabrum has two phytochrome photoreceptors, Agp1 and Agp2. We 16 found that DNA transfer into plants by A. fabrum is down regulated by light and that 17 phytochrome knockout mutants have diminished DNA transfer rates. The regulation pattern 18 matches with that of bacterial conjugation reported earlier. Growth, swimming and interbacterial 19 competition were also affected in phytochrome knockout mutants, although these effects were 20 often not affected by light. We can thus distinguish between light-regulated and light-independent 21 phytochrome responses. In microarray studies, transcription of only 4 genes was affected by 22 light, indicating that most light responses are regulated post-transcriptionally. In a mass 23 spectrometery-based proteomic study, 24 proteins were different between light and dark grown 24 bacteria, whereas 382 proteins differed between wild type and phytochrome knockout mutants, 25 pointing again to light-dependent and light-independent roles of Agp1 and Agp2. 26 27 stranded DNA is covalently attached to the protein that makes the nick, which is VirD2 (21) in A. 59 fabrum plant infection and TraA (22) in conjugation. During conjugation, the entire plasmid is 60 transferred. The complex of protein and single-strand DNA is transferred through pili formed by 61 the type IV secretion system into the target cells. 62We also tested the impact of phytochromes in A. fabrum on growth, motility, and 63 interbacterial competition and also performed microarray and proteome studies. These data show 64 that protein levels are affected for few gene products and suggests regulatory mechanisms 65 independent on transcription or translation. On the organismal level and on the level of single 66 proteins, we found phytochrome effects that are light dependent and such that are light 67 independent. 68

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phytochrome mediated responses inAgrobacterium fabrum: growth, swimming, plant infection and interbacterial competition

Xue

Bai

Rottwinkel

et al. 2020

Preprint

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“…In particular, photoreceptors are known to influence motility in P. syringae pv. syringae (Pss) B728a (Wu et al, 2013), plasmid conjugation in Agrobacterium fabrum (Bai et al, 2016), and motility, adhesion and virulence in Xanthomonas axonopodis pv. citri (Kraiselburd et al, 2012) and Xanthomonas campestris pv.…”

Section: Discussionmentioning

confidence: 99%

Pseudomonas syringaepv. tomato exploits light signals to optimize virulence and colonization of leaves

Santamaría‐Hernando

Rodríguez‐Herva

Martínez-García

et al. 2018

Environmental Microbiology

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Light is pervasive in the leaf environment, creating opportunities for both plants and pathogens to cue into light as a signal to regulate plant-microbe interactions. Light enhances plant defences and regulates opening of stomata, an entry point for foliar bacterial pathogens such as Pseudomonas syringae pv. tomato DC3000 (PsPto). The effect of light perception on gene expression and virulence was investigated in PsPto. Light induced genetic reprogramming in PsPto that entailed significant changes in stress tolerance and virulence. Blue light-mediated up-regulation of type three secretion system genes and red light-mediated down-regulation of coronatine biosynthesis genes. Cells exposed to white light, blue light or darkness before inoculation were more virulent when inoculated at dawn than dusk probably due to an enhanced entry through open stomata. Exposure to red light repressed coronatine biosynthesis genes which could lead to a reduced stomatal re-opening and PsPto entry. Photoreceptor were required for the greater virulence of light-treated and dark-treated PsPto inoculated at dawn as compared to dusk, indicating that these proteins sense the absence of light and contribute to priming of virulence in the dark. These results support a model in which PsPto exploits light changes to maximize survival, entry and virulence on plants.

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“…Fungal phytochromes control the differentiation between sexual and vegetative development and are involved in stress regulation . In some photosynthetic bacteria, phytochromes control photosynthesis‐related proteins and photosynthesis pigments , whereas in the non‐photosynthetic soil bacterium Agrobacterium fabrum , gene transfer to plants and conjugation are controlled by phytochrome . Phytochromes are dimeric proteins which typically consist of two identical subunits.…”

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Evidence for weak interaction between phytochromes Agp1 and Agp2 from Agrobacterium fabrum

et al. 2019

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During bacterial conjugation, plasmid DNA is transferred from cell to cell. In Agrobacterium fabrum, conjugation is regulated by the phytochrome photoreceptors Agp1 and Agp2. Both contribute equally to this regulation. Agp1 and Agp2 are histidine kinases, but, for Agp2, we found no autophosphorylation activity. A clear autophosphorylation signal, however, was obtained with mutants in which the phosphoaccepting Asp of the C‐terminal response regulator domain is replaced. Thus, the Agp2 histidine kinase differs from the classical transphosphorylation pattern. We performed size exclusion, photoconversion, dark reversion, autophosphorylation, chromophore assembly kinetics and fluorescence resonance energy transfer measurements on mixed Agp1/Agp2 samples. These assays pointed to an interaction between both proteins. This could partially explain the coaction of both phytochromes in the cell.

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Bacteriophytochromes control conjugation in Agrobacterium fabrum

Cited by 33 publications

References 46 publications

Phytochrome mediated responses inAgrobacterium fabrum: growth, swimming, plant infection and interbacterial competition

Phytochrome mediated responses inAgrobacterium fabrum: growth, swimming, plant infection and interbacterial competition

Pseudomonas syringaepv. tomato exploits light signals to optimize virulence and colonization of leaves

Evidence for weak interaction between phytochromes Agp1 and Agp2 from Agrobacterium fabrum

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