AlgU, a Conserved Sigma Factor Regulating Abiotic Stress Tolerance and Promoting Virulence in<i>Pseudomonas syringae</i>

Hai-bi, Wang; Yang, Zichu; Swingle, Bryan; Kvitko, Brian H.

doi:10.1094/mpmi-09-20-0254-cr

Cited by 19 publications

(10 citation statements)

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“…AlgU regulates the expression of osmotic and oxidative stress response genes in different bacteria [ 14 ]. Alginate, a secreted polysaccharide, is also generally considered to shield bacteria from external stressors [ 15 , 16 ].…”

Section: Resultsmentioning

confidence: 99%

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon

et al. 2022

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In previous work, we determined the transcriptomic impacts of flg22 pre-induced Pattern Triggered Immunity (PTI) in Arabidopsis thaliana on the pathogen Pseudomonas syringae pv. tomato DC3000 (Pto). During PTI exposure we observed expression patterns in Pto reminiscent of those previously observed in a Pto algU mutant. AlgU is a conserved extracytoplasmic function sigma factor which has been observed to regulate over 950 genes in Pto in growth media. We sought to identify the AlgU regulon when the bacteria are inside the plant host and which PTI-regulated genes overlapped with AlgU-regulated genes. In this study, we analyzed transcriptomic data from RNA-sequencing to identify the AlgU regulon (while in the host) and its relationship with PTI. Our results showed that the upregulation of 224 genes while inside the plant host require AlgU, while another 154 genes are downregulated dependent on AlgU in Arabidopsis during early infection. Both stress response and virulence-associated genes were upregulated in a manner dependent on AlgU, while the flagellar motility genes are downregulated in a manner dependent on AlgU. Under the pre-induced PTI condition, more than half of these AlgU-regulated genes have lost induction/suppression in contrast to mock treated plants, and almost all function groups regulated by AlgU were affected by PTI.

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Section: Resultsmentioning

confidence: 99%

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon

et al. 2022

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“…Plant pathogenic bacteria usually encounter various challenges in diverse natural environments, such as drought, ultraviolet radiation, temperature fluctuations and ROS produced by the plant immune system. It is crucial for phytopathogenic bacteria to sense environmental stimuli and alter the expression of stress‐related genes rapidly in response to environmental challenges (Keith & Bender, 1999; Miller et al, 2001; Wang et al, 2021b). The RetS‐Gac‐Rsm regulatory system governs various phenotypes, including motility, biofilm formation, extracellular enzymes, secretion systems, quorum‐sensing molecules and other virulence factors (Lapouge et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

RsmA3 modulates RpoS through the RetS‐Gac‐Rsm signalling pathway in response to H₂O₂ stress in the phytopathogen Pseudomonas syringae

Meng

Tan

et al. 2022

Environmental Microbiology

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Reactive oxygen species are a fatal challenge to the plant pathogenic bacterium Pseudomonas syringae. In this study, we reveal that the global regulatory protein RsmA3 from the RetS‐Gac/Rsm signalling pathway modulates RpoS in the early‐log growth phase in the P. syringae wild‐type strain MB03, thereby regulating oxidative tolerance to H2O2 and ultimately affecting pathogenicity to the host plant. Following increased H2O2 by external addition or endogenous induction by menadione, the resistance of the mutant strain ΔretS to H2O2 is significantly enhanced due to rapid increases in the transcription of Rsm‐related non‐coding small RNAs (nc sRNAs), a sigma factor RpoS, and H2O2‐detoxifying enzymes. Moreover, the ΔretS mutant is significantly less pathogenic in cucumber leaves. Seven Rsm‐related nc sRNAs (namely, rsmZ, rsmY and rsmX1–5) show functional redundancy in the RetS‐Gac‐Rsm signalling pathway. External addition of H2O2 stimulates increases in the transcription of both rsmY and rsmZ. Thus, we propose a regulatory model of the RetS‐Gac‐Rsm signalling pathway in P. syringae MB03 for the regulation of H2O2 tolerance and phytopathogenicity in the host plant.

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“…Bacterial Alginate Biosynthesis and Metabolism DOI: http://dx.doi.org/10.5772/intechopen.109295 AlgU, previously called AlgT, δ E , or δ 22 [87], is homologous to the alternative sigma factor of the stress response regulator RpoE from Escherichia coli [88] and plays a key role as the main regulator of bacterial alginate biosynthesis. AlgU ist is encoded together with the mucABCD operon, which contains four genes (mucA, mucB, mucC, and mucD).…”

Section: Genetic Organization Of Alginate Biosynthesis/regulation Rel...mentioning

confidence: 99%

Bacterial Alginate Biosynthesis and Metabolism

Serrato¹

2024

Biochemistry

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Alginate is a linear anionic heteropolysaccharide with a chemical structure consisting of 1,4-linked subunits of β-D-mannuronic acid (M) and its C-5 epimer α-L-guluronic acid (G). It is well known that the monomer composition and molecular weight of alginates affect their properties and influence their use in the food and pharmaceutical industries. Alginate is usually extracted from seaweed for commercial purposes, but can also be produced by bacteria as exopolysaccharide (EPS). Pseudomonas spp. and Azotobacter vinelandii are well-known alginate-producing microorganisms. Their biochemical machinery for alginate biosynthesis is influenced by changing culture conditions and manipulating genes/proteins, making it relatively easy to obtain customized EPS with different molecular weights, M/G compositions, and thus physicochemical properties. Although these two genera have very similar biosynthetic pathways and molecular mechanisms for alginate production, with most of the genes involved being virtually identical, their regulation has been shown to be somewhat different. In this chapter, we present the main steps of alginate biosynthesis in bacteria, including precursor synthesis, polymerization, periplasmic modifications, transport/secretion, and post-secretion modification.

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AlgU, a Conserved Sigma Factor Regulating Abiotic Stress Tolerance and Promoting Virulence inPseudomonas syringae

Cited by 19 publications

References 145 publications

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon

RsmA3 modulates RpoS through the RetS‐Gac‐Rsm signalling pathway in response to H₂O₂ stress in the phytopathogen Pseudomonas syringae

Bacterial Alginate Biosynthesis and Metabolism

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AlgU, a Conserved Sigma Factor Regulating Abiotic Stress Tolerance and Promoting Virulence inPseudomonas syringae

Cited by 19 publications

References 145 publications

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon

In planta transcriptomics reveals conflicts between pattern-triggered immunity and the AlgU sigma factor regulon

RsmA3 modulates RpoS through the RetS‐Gac‐Rsm signalling pathway in response to H2O2 stress in the phytopathogen Pseudomonas syringae

Bacterial Alginate Biosynthesis and Metabolism

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RsmA3 modulates RpoS through the RetS‐Gac‐Rsm signalling pathway in response to H₂O₂ stress in the phytopathogen Pseudomonas syringae