S-Nitrosylation of the virulence regulator AphB promotes Vibrio cholerae pathogenesis

Chen, Jiandong; Byun, Hyuntae; She, Qianxuan; Li, Zhi; Ruggeberg, Karl-Gustav; Pu, Qinqin; Jung, I-Ji; Zhu, Dehao; Brockett, Mary R.; Hsiao, Ansel; Zhu, Jun

doi:10.1371/journal.ppat.1010581

“…We found the uncharacterized L. pneumophila-encoded Ceg10 protein to reproducibly break viral restriction in LD652 cells. Interestingly, the conserved catalytic cysteine, Cys-159 (C159), is nitrosylated in two of our three structural data sets, indicating that this cysteine is highly reactive [84]. To date, of the >215,000 structures available on the Protein Data Bank, only 43 deposits display an S-nitrosothiol group, highlighting the unique nature of this modification.…”

Section: Discussionmentioning

confidence: 84%

“…Interestingly, the conserved catalytic cysteine, Cys-159 (C159), is nitrosylated in two of our three structural data sets, indicating that this cysteine is highly reactive and particularly susceptible to oxidation by agents such as nitric oxide. Recent studies indicate that S-nitrosylation of the Vibrio cholera virulence regulator AphB suppresses the enzymatic activity and alters virulence gene expression [84]. To date, of the >215,000 structures available on the Protein Data Bank, only 43 deposits display an S-nitrosothiol group, highlighting the unique nature of this modification.…”

Section: Discussionmentioning

confidence: 99%

“…Through independent UBAIT- and Y2H-based screening methods, we identified host SHOC2 and PSMC1 proteins as conserved IpaH4 substrates in moth and human cells. SHOC2 is a leucine-rich repeat scaffold protein that forms a ternary complex with MRAS and PP1C that activates rapidly accelerated fibrosarcoma (RAF) kinases [85, 86]. Although the specific role of SHOC2 during virus infection is unclear, it has recently been shown to activate ERK/STAT signaling in response to bacterial flagellin in shrimp hosts [87], implying that SHOC2 may indeed have conserved roles in combating bacterial and viral pathogens.…”

Section: Discussionmentioning

confidence: 99%

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Exploiting Bacterial Effector Proteins to Uncover Evolutionarily Conserved Antiviral Host Machinery

Embry,

Baggett,

Heisler

et al. 2024

Preprint

1

0

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Arboviruses are a diverse group of insect-transmitted pathogens that pose global public health challenges. Identifying evolutionarily conserved host factors that combat arbovirus replication in disparate eukaryotic hosts is important as they may tip the balance between productive and abortive viral replication, and thus determine virus host range. Here, we exploit naturally abortive arbovirus infections that we identified in lepidopteran cells and use bacterial effector proteins to uncover host factors restricting arbovirus replication. Bacterial effectors are proteins secreted by pathogenic bacteria into eukaryotic hosts cells that can inhibit antimicrobial defenses. Since bacteria and viruses can encounter common host defenses, we hypothesized that some bacterial effectors may inhibit host factors that restrict arbovirus replication in lepidopteran cells. Thus, we used bacterial effectors as molecular tools to identify host factors that restrict four distinct arboviruses in lepidopteran cells. By screening 210 effectors encoded by seven different bacterial pathogens, we identify six effectors that individually rescue the replication of all four arboviruses. We show that these effectors encode diverse enzymatic activities that are required to break arbovirus restriction. We further characterizeShigella flexneri-encoded IpaH4 as an E3 ubiquitin ligase that directly ubiquitinates two evolutionarily conserved proteins, SHOC2 and PSMC1, promoting their degradation in insect and human cells. We show that depletion of either SHOC2 or PSMC1 in insect or human cells promotes arbovirus replication, indicating that these are ancient virus restriction factors conserved across invertebrate and vertebrate hosts. Collectively, our study reveals a novel pathogen-guided approach to identify conserved antimicrobial machinery, new effector functions, and conserved roles for SHOC2 and PSMC1 in virus restriction.Author SummaryMicrobial pathogens such as viruses and bacteria encounter diverse host cell responses during infection. While viruses possess antagonists to counter these responses in natural host species, their replication can be restricted in unnatural host cells where their antagonists are ineffective. Bacteria also employ a diverse repertoire of immune evasion proteins known as “effectors” that can inhibit antimicrobial responses found in invertebrate and vertebrate hosts. In this study, we hypothesized that some bacterial effectors may target host immunity proteins that restrict both bacteria and viruses. To test this hypothesis, we screened a bacterial effector library comprising 210 effectors from seven distinct bacterial pathogens for their ability to rescue the replication of four viruses in insect cells that are normally non-permissive to these viruses. Though numerous effectors were identified to rescue the replication of each virus, the uncharacterized IpaH4 protein encoded by the human pathogenShigella flexneriwas able to rescue all four viruses screened. We discovered that IpaH4 enhances arbovirus replication in both restrictive insect and permissive human cells by directly targeting two novel, evolutionarily conserved antiviral host proteins, SHOC2 and PSMC1, for degradation. Our study establishes bacterial effectors as valuable tools for identifying critical antimicrobial machinery employed by eukaryotic hosts.

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“…Interestingly, the conserved catalytic cysteine, Cys-159 (C159), is nitrosylated in two of our three structural data sets, indicating that this cysteine is highly reactive and particularly susceptible to oxidation by agents such as nitric oxide. Recent studies indicate that S-nitrosylation of the Vibrio cholerae virulence regulator AphB suppresses its enzymatic activity and alters virulence gene expression [ 86 ]. To date, of the >215,000 structures available on the Protein Data Bank, only 43 deposits display an S-nitrosothiol group, highlighting the unique nature of this modification.…”

Section: Discussionmentioning

confidence: 99%

Exploiting bacterial effector proteins to uncover evolutionarily conserved antiviral host machinery

Embry,

Baggett,

Heisler

et al. 2024

PLoS Pathog

3

0

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Arboviruses are a diverse group of insect-transmitted pathogens that pose global public health challenges. Identifying evolutionarily conserved host factors that combat arbovirus replication in disparate eukaryotic hosts is important as they may tip the balance between productive and abortive viral replication, and thus determine virus host range. Here, we exploit naturally abortive arbovirus infections that we identified in lepidopteran cells and use bacterial effector proteins to uncover host factors restricting arbovirus replication. Bacterial effectors are proteins secreted by pathogenic bacteria into eukaryotic hosts cells that can inhibit antimicrobial defenses. Since bacteria and viruses can encounter common host defenses, we hypothesized that some bacterial effectors may inhibit host factors that restrict arbovirus replication in lepidopteran cells. Thus, we used bacterial effectors as molecular tools to identify host factors that restrict four distinct arboviruses in lepidopteran cells. By screening 210 effectors encoded by seven different bacterial pathogens, we identify several effectors that individually rescue the replication of all four arboviruses. We show that these effectors encode diverse enzymatic activities that are required to break arbovirus restriction. We further characterize Shigella flexneri-encoded IpaH4 as an E3 ubiquitin ligase that directly ubiquitinates two evolutionarily conserved proteins, SHOC2 and PSMC1, promoting their degradation in insect and human cells. We show that depletion of either SHOC2 or PSMC1 in insect or human cells promotes arbovirus replication, indicating that these are ancient virus restriction factors conserved across invertebrate and vertebrate hosts. Collectively, our study reveals a novel pathogen-guided approach to identify conserved antimicrobial machinery, new effector functions, and conserved roles for SHOC2 and PSMC1 in virus restriction.

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“…HypT is activated by HOCl-dependent oxidation of a methionine (60). In AphB from Vibrio cholerae, a virulence factor that senses low pH and low oxygen, cysteine residues may act as thiol-based switches (17,69,78).…”

Section: Molecular Features Of Effector Bindingmentioning

confidence: 99%

Versatility and Complexity: Common and Uncommon Facets of LysR-Type Transcriptional Regulators

Baugh

¹

,

Momany

²

,

Neidle

³

2023

Annu. Rev. Microbiol.

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LysR-type transcriptional regulators (LTTRs) form one of the largest families of bacterial regulators. They are widely distributed and contribute to all aspects of metabolism and physiology. Most are homotetramers, with each subunit composed of an N-terminal DNA-binding domain followed by a long helix connecting to an effector-binding domain. LTTRs typically bind DNA in the presence or absence of a small-molecule ligand (effector). In response to cellular signals, conformational changes alter DNA interactions, contact with RNA polymerase, and sometimes contact with other proteins. Many are dual-function repressor–activators, although different modes of regulation may occur at multiple promoters. This review presents an update on the molecular basis of regulation, the complexity of regulatory schemes, and applications in biotechnology and medicine. The abundance of LTTRs reflects their versatility and importance. While a single regulatory model cannot describe all family members, a comparison of similarities and differences provides a framework for future study. Expected final online publication date for the Annual Review of Microbiology, Volume 77 is September 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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S-Nitrosylation of the virulence regulator AphB promotes Vibrio cholerae pathogenesis

Cited by 8 publications

References 48 publications

Exploiting Bacterial Effector Proteins to Uncover Evolutionarily Conserved Antiviral Host Machinery

Exploiting Bacterial Effector Proteins to Uncover Evolutionarily Conserved Antiviral Host Machinery

Exploiting bacterial effector proteins to uncover evolutionarily conserved antiviral host machinery

Versatility and Complexity: Common and Uncommon Facets of LysR-Type Transcriptional Regulators

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