Discovery of the extracytoplasmic function σ factors

Lonetto, Michael A.; Donohue, Timothy J.; Gross, Carol A.; Buttner, Mark J.

doi:10.1111/mmi.14307

Cited by 20 publications

(12 citation statements)

References 54 publications

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“…One pathway relies on a form of vitamin B 12 and its association with a single photoreceptor-cum-transcriptional factor, and the other is a B 12 -independent, more complex route that requires various singular factors. Many worthy firsts can be credited to elucidation of the two pathways, including the discovery of one of the first ECF-σ factors, CarQ [ 83 , 84 ]; the founding members of large protein families, notably the B 12 -based CarH photoreceptor family [ 19 , 20 , 21 , 22 ] and the CarD_CdnL family of RNAP-binding transcription factors [ 102 , 103 , 110 ]; the long-sought human desaturase involved in plasmalogen biosynthesis through its M. xanthus CarF homolog [ 23 ]. Insights specific to M. xanthus and closely related bacteria, but also ones more broadly conserved across bacteria, have emerged.…”

Section: Discussionmentioning

confidence: 99%

“…While CarS turned out to be the trans acting antirepressor of CarA [ 57 , 82 ], CarQ was identified as the founding member of a new, large and diverse group of alternative σ factors known as the extracytoplasmic function or ECF-σ factors, which were first discovered over 25 years ago [ 83 , 84 ]. Usually, ECF-σ act in a gamut of cellular responses to a variety of extracytoplasmic stimuli (hence the name) and are negatively regulated by association with cognate anti-σ factors, which are often membrane-bound and coexpressed with their ECF-σ partner [ 85 ].…”

Section: Blue Light Sensing Signaling and Gene Regulation In The B 12 -Independent Pathwaymentioning

confidence: 99%

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Light-Triggered Carotenogenesis in Myxococcus xanthus: New Paradigms in Photosensory Signaling, Transduction and Gene Regulation

et al. 2021

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Myxobacteria are Gram-negative δ-proteobacteria found predominantly in terrestrial habitats and often brightly colored due to the biosynthesis of carotenoids. Carotenoids are lipophilic isoprenoid pigments that protect cells from damage and death by quenching highly reactive and toxic oxidative species, like singlet oxygen, generated upon growth under light. The model myxobacterium Myxococcus xanthus turns from yellow in the dark to red upon exposure to light because of the photoinduction of carotenoid biosynthesis. How light is sensed and transduced to bring about regulated carotenogenesis in order to combat photooxidative stress has been extensively investigated in M. xanthus using genetic, biochemical and high-resolution structural methods. These studies have unearthed new paradigms in bacterial light sensing, signal transduction and gene regulation, and have led to the discovery of prototypical members of widely distributed protein families with novel functions. Major advances have been made over the last decade in elucidating the molecular mechanisms underlying the light-dependent signaling and regulation of the transcriptional response leading to carotenogenesis in M. xanthus. This review aims to provide an up-to-date overview of these findings and their significance.

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Section: Discussionmentioning

confidence: 99%

Section: Blue Light Sensing Signaling and Gene Regulation In The B 12 -Independent Pathwaymentioning

confidence: 99%

Light-Triggered Carotenogenesis in Myxococcus xanthus: New Paradigms in Photosensory Signaling, Transduction and Gene Regulation

et al. 2021

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“…Control is mediated via the binding of the ECF-sigma by its cognate anti-sigma factor, usually coded by a gene that is co-transcribed with the ECF-sigma. In response to environmental stimuli, the anti-sigma releases the ECF-sigma, allowing the cell to moderate gene expression and respond to environmental fluctuations (reviewed in Lonetto, et al 10 ).…”

Section: Introductionmentioning

confidence: 99%

“…Despite the discovery of ECFs in 1994 10 , detailed information regarding how these proteins evolved is still sparse. ECFs show great diversity and have been classified in 157 well-defined phylogenetic families 17 – 20 .…”

Section: Introductionmentioning

confidence: 99%

The novel ECF56 SigG1-RsfG system modulates morphological differentiation and metal-ion homeostasis in Streptomyces tsukubaensis

Oliveira¹,

Bush²,

Pires³

et al. 2020

Sci Rep

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Extracytoplasmic function (ECF) sigma factors are key transcriptional regulators that prokaryotes have evolved to respond to environmental challenges. Streptomyces tsukubaensis harbours 42 ECFs to reprogram stress-responsive gene expression. Among them, SigG1 features a minimal conserved ECF σ2–σ4 architecture and an additional C-terminal extension that encodes a SnoaL_2 domain, which is characteristic for ECF σ factors of group ECF56. Although proteins with such domain organisation are widely found among Actinobacteria, the functional role of ECFs with a fused SnoaL_2 domain remains unknown. Our results show that in addition to predicted self-regulatory intramolecular amino acid interactions between the SnoaL_2 domain and the ECF core, SigG1 activity is controlled by the cognate anti-sigma protein RsfG, encoded by a co-transcribed sigG1-neighbouring gene. Characterisation of ∆sigG1 and ∆rsfG strains combined with RNA-seq and ChIP-seq experiments, suggests the involvement of SigG1 in the morphological differentiation programme of S. tsukubaensis. SigG1 regulates the expression of alanine dehydrogenase, ald and the WhiB-like regulator, wblC required for differentiation, in addition to iron and copper trafficking systems. Overall, our work establishes a model in which the activity of a σ factor of group ECF56, regulates morphogenesis and metal-ions homeostasis during development to ensure the timely progression of multicellular differentiation.

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“…Currently, bacterial σ factors can be classified into two large and structurally unrelated protein families, σ 54 and σ 70 (Helmann and Chamberlin, ; Gross et al , ), of which the latter is by far the most abundant, with about 20 times more members (El‐Gebali et al , ). This σ factor family includes the essential housekeeping σ factors (Group I) and three alternative σ factor groups defined based on sequence similarity and function (Helmann and Chamberlin, ; Lonetto et al , ; Helmann, ; Gruber and Gross, ; Lonetto et al , ): Group II includes the non‐essential paralogs of the housekeeping σ factors; Group III contains the flagellar, heat shock and sporulation‐specific σ factors; and Group IV corresponds to the extracytoplasmic function σ factors (ECFs). The ECF family of σ factors was defined 25 years ago based on the initial analysis of the small number of examples known at the time, all of which respond to extracellular cues such as periplasmic stress, heat shock, iron transport or protein secretion (Lonetto et al , ).…”

Section: Introductionmentioning

confidence: 99%

ECF σ factors with regulatory extensions: the one‐component systems of the σ universe

Pinto

Liu

Mascher

2019

Molecular Microbiology

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The σ subunit of the bacterial RNA polymerase determines promoter specificity. The extracytoplasmic function σ factors (ECFs) represent the most abundant and diverse group of alternative σ factors and are present in the vast majority of bacterial genomes. Typically, ECFs are regulated by anti-σ factors that sequester their cognate ECFs, thereby preventing their interaction with the RNA polymerase. Beyond these ECF paradigms, a number of distinct modes of regulation have been proposed and experimentally investigated. Regulatory extensions represent one such alternative mechanism of ECF regulation that can be found in 18 phylogenetically distinct ECF groups. Here, the σ factors contain additional domains that are fused to the ECF core domains and are involved in stimulus perception and modulation of σ factor activity. We will summarize the current state of knowledge on regulating ECF activity by C-terminal extensions. We will also discuss newly identified ECF groups containing either N-or C-terminal extensions and propose possible mechanisms by which these extensions have been generated and affect ECF σ factor activity. Based on their modular architecture and the resulting physical connection between stimulus perception and transcriptional output, these ECFs are analogous to one-component systems, the primary mechanism of bacterial signal transduction. contributed equally to the writing of this review.

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Discovery of the extracytoplasmic function σ factors

Cited by 20 publications

References 54 publications

Light-Triggered Carotenogenesis in Myxococcus xanthus: New Paradigms in Photosensory Signaling, Transduction and Gene Regulation

Light-Triggered Carotenogenesis in Myxococcus xanthus: New Paradigms in Photosensory Signaling, Transduction and Gene Regulation

The novel ECF56 SigG1-RsfG system modulates morphological differentiation and metal-ion homeostasis in Streptomyces tsukubaensis

ECF σ factors with regulatory extensions: the one‐component systems of the σ universe

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