Identification of Diverse Toxin Complex Clusters and an eCIS Variant in Serratia proteamaculans Pathovars of the New Zealand Grass Grub (
            <i>Costelytra Giveni</i>
            ) and Manuka Beetle (
            <i>Pyronota</i>
            Spp.) Larvae

Hurst, Mark R. H.; Beattie, Amy; Laugraud, Aurélie; Townsend, R.J.; Sitter, Thomas; Koten, Chikako van; Harper, Lincoln A.

doi:10.1128/spectrum.01123-21

Cited by 6 publications

(7 citation statements)

References 56 publications

(94 reference statements)

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“…Direct nucleotide sequence comparison of the tcC components is hindered by several Tcs encoding for two TcC components and some, such as the S. proteamaculans D1.p1, Sm1a.p2, p1457, pD, p336, p1770, p1769, and p299, lack the tcC altogether. Additionally, the 3′ region of the tcC genes is highly divergent (Hurst et al, 2021 ). Higher variation in the tc clusters may be a result of selective host or environmental pressure.…”

Section: Resultsmentioning

confidence: 99%

“…Gray shade denotes non‐ Serratia transmissible adaptive mega‐plasmids (STAMPs); blue Serratia entomophila ; pink Serratia proteamaculans ; yellow Yersinia frederiksenii . The right column denotes the different TcA clusters (Hurst et al, 2021 ).…”

Section: Resultsmentioning

confidence: 99%

“…ABC Tcs consist of three components, TcA, TcB, and TcC, which have since been identified in a wide range of microbial species including Xenorhabdus nematophilus (Morgan et al, 2001 ), Yersinia frederiksenii (Dodd et al, 2006 ), B. thuringiensis (Blackburn et al, 2011 ) and Pseudomonas fluorescens (Rangel et al, 2016 ). In these ABC complexes, the TcC component is the toxic effector (Hurst et al, 2021 ; Zhang et al, 2012 ). The C‐terminus of the TcC effector is enveloped by TcB and docks to the TcA pentamer (Busby et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

“…The Y. frederiksenii 49 49.p1 encodes the ABC toxin complex Y. frederiksenii (TcYF) operon, which shares 79.5% and 73.4% nucleotide sequence similarity to the pADAP sep tc and pU143 spp tc operon respectively, yet Y. frederiksenii 49 is ineffective towards challenged C. giveni larvae (Dodd et al, 2006 ). Other Serratia Tc encoding plasmids include the S. proteamaculans isolate p159 (Dodd et al, 2006 ), Man 4 and C (Hurst et al, 2021 ) all presenting varying bioactivity towards C. giveni and Pyronota species. The observed variation in host ranges and virulence phenotypes of Serratia isolates led to 76 Serratia isolates being sequenced and screened for the presence of additional pathogenicity‐associated genetic components (Sitter et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

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Serratia‐based toxin cluster elements are associated with a type I fimbria

Sitter,

Schoof,

Glare

et al. 2024

MicrobiologyOpen

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A soil bacterium in the Serratia genus, carrying a 153 kb conjugative amber disease‐associated plasmid (pADAP), is commercially exploited for population control of the New Zealand endemic pest beetle Costelytra giveni (Coleoptera: Scarabaeidae). The main insecticidal elements are an anti‐feeding prophage and the Sep ABC toxin complex (Tc). Homologs of pADAP, encoding variant Tcs, convey different beetle disease phenotypes. To investigate the correlation between variable bioactivity and the Tc variant, 76 Serratia plasmids were sequenced, resulting in the identification of four additional tc variants. All Serratia tc variants were found to be colocated with a conserved type 1 sef fimbrial‐like operon, indicating a conserved sef‐tc genetic island not observed outside of the Serratia genus. The conserved co‐location of the fimbrial and tc genes suggests the fimbriae somehow contribute to the lifestyle of Tc‐producing cells. Expression of the sef operon in a fim‐null Escherichia coli strain revealed fimbriae presence while a constructed sef‐deficient mutant showed no reduction of virulence or host colonization. Although no detectable contribution of Sef to amber disease in C. giveni was observed, the Sef adhesin sequences clustered similarly to the Serratia species encoding it, suggesting Sef has a species‐specific function.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Serratia‐based toxin cluster elements are associated with a type I fimbria

Sitter,

Schoof,

Glare

et al. 2024

MicrobiologyOpen

Self Cite

View full text Add to dashboard Cite

show abstract

“…Some of the earliest studies of ABC toxins identified that the TcA component was involved in membrane binding and establishing host specificity [ 8 , 27 , 28 ]. With the determination of the first high-resolution structures, it was proposed that differences in specificity could be attributed to the variable incorporation of Ig-like domains into the TcA shell, identified at the time as putative receptor-binding domains ( Figure 2 ) [ 19 ].…”

Section: Host Cell Recognitionmentioning

confidence: 99%

Recent insights into mechanisms of cellular toxicity and cell recognition associated with the ABC family of pore-forming toxins

Aleksandrova

Roche

Low

et al. 2023

Biochemical Society Transactions

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ABC toxins are pore-forming toxins characterised by the presence of three distinct components assembled into a hetero-oligomeric toxin complex ranging in size from 1.5–2.5 MDa. Most ABC toxins studied to date appear to be insecticidal toxins, although genes predicted to encode for homologous assemblies have also been found in human pathogens. In insects, they are delivered to the midgut either directly via the gastrointestinal tract, or via a nematode symbiont, where they attack the epithelial cells and rapidly trigger widespread cell death. At the molecular level, the homopentameric A subunit is responsible for binding to lipid bilayer membranes and introducing a protein translocation pore, through which a cytotoxic effector — encoded at the C-terminus of the C subunit — is delivered. The B subunit forms a protective cocoon that encapsulates the cytotoxic effector, part of which is contributed by the N-terminus of the C subunit. The latter also includes a protease motif that cleaves the cytotoxic effector, releasing it into the pore lumen. Here, we discuss and review recent studies that begin to explain how ABC toxins selectively target specific cells, establishing host tropism, and how different cytotoxic effectors trigger cell death. These findings allow for a more complete understanding of how ABC toxins function in an in vivo context, which in turn provides a stronger foundation for understanding how they cause disease in invertebrate (and potentially also vertebrate) hosts, and how they might be re-engineered for therapeutic or biotechnological purposes.

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Identification of novel toxins associated with the extracellular contractile injection system using machine learning

Danov,

Pollin,

Moon

et al. 2024

Mol Syst Biol

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Secretion systems play a crucial role in microbe-microbe or host-microbe interactions. Among these systems, the extracellular contractile injection system (eCIS) is a unique bacterial and archaeal extracellular secretion system that injects protein toxins into target organisms. However, the specific proteins that eCISs inject into target cells and their functions remain largely unknown. Here, we developed a machine learning classifier to identify eCIS-associated toxins (EATs). The classifier combines genetic and biochemical features to identify EATs. We also developed a score for the eCIS N-terminal signal peptide to predict EAT loading. Using the classifier we classified 2,194 genes from 950 genomes as putative EATs. We validated four new EATs, EAT14-17, showing toxicity in bacterial and eukaryotic cells, and identified residues of their respective active sites that are critical for toxicity. Finally, we show that EAT14 inhibits mitogenic signaling in human cells. Our study provides insights into the diversity and functions of EATs and demonstrates machine learning capability of identifying novel toxins. The toxins can be employed in various applications dependently or independently of eCIS.

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Identification of Diverse Toxin Complex Clusters and an eCIS Variant in Serratia proteamaculans Pathovars of the New Zealand Grass Grub ( Costelytra Giveni ) and Manuka Beetle ( Pyronota Spp.) Larvae

Cited by 6 publications

References 56 publications

Serratia‐based toxin cluster elements are associated with a type I fimbria

Serratia‐based toxin cluster elements are associated with a type I fimbria

Recent insights into mechanisms of cellular toxicity and cell recognition associated with the ABC family of pore-forming toxins

Identification of novel toxins associated with the extracellular contractile injection system using machine learning

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