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•Characterization of a member of the new MuF polymorphic toxin family.•The MuF polymorphic toxin from Streptococcus pneumoniae is a (p)ppApp synthetase.•Two immune proteins inhibit ...the toxin and hydrolyze (p)ppApp.•Distinct signatures for (p)ppGpp and (p)ppApp synthetases.•(p)ppApp synthetases are found associated with T6SS and temperate phages.
Polymorphic toxins (PTs) are a broad family of toxins involved in interbacterial competition and pathogenesis. PTs are modular proteins that are comprised of a conserved N-terminal domain responsible for its transport, and a variable C-terminal domain bearing toxic activity. Although the mode of transport has yet to be elucidated, a new family of putative PTs containing an N-terminal MuF domain, resembling the Mu coliphage F protein, was identified in prophage genetic elements. The C-terminal toxin domains of these MuF PTs are predicted to bear nuclease, metallopeptidase, ADP-ribosyl transferase and RelA_SpoT activities. In this study, we characterized the MuF-RelA_SpoT toxin associated with the temperate phage of Streptococcus pneumoniae SPNA45. We show that the RelA_SpoT domain has (p)ppApp synthetase activity, which is bactericidal under our experimental conditions. We further determine that the two genes located downstream encode two immunity proteins, one binding to and inactivating the toxin and the other detoxifying the cell via a pppApp hydrolase activity. Finally, based on protein sequence alignments, we propose a signature for (p)ppApp synthetases that distinguishes them from (p)ppGpp synthetases.
Background
Growing up on traditional, single‐family farms is associated with protection against asthma in school age, but the mechanisms against early manifestations of atopic disease are largely ...unknown. We sought determine the gut microbiome and metabolome composition in rural Old Order Mennonite (OOM) infants at low risk and Rochester, NY urban/suburban infants at high risk for atopic diseases.
Methods
In a cohort of 65 OOM and 39 Rochester mother‐infant pairs, 101 infant stool and 61 human milk samples were assessed by 16S rRNA gene sequencing for microbiome composition and qPCR to quantify Bifidobacterium spp. and B. longum ssp. infantis (B. infantis), a consumer of human milk oligosaccharides (HMOs). Fatty acids (FAs) were analyzed in 34 stool and human 24 milk samples. Diagnoses and symptoms of atopic diseases by 3 years of age were assessed by telephone.
Results
At a median age of 2 months, stool was enriched with Bifidobacteriaceae, Clostridiaceae, and Aerococcaceae in the OOM compared with Rochester infants. B. infantis was more abundant (p < .001) and prevalent, detected in 70% of OOM compared with 21% of Rochester infants (p < .001). Stool colonized with B. infantis had higher levels of lactate and several medium‐ to long/odd‐chain FAs. In contrast, paired human milk was enriched with a distinct set of FAs including butyrate. Atopic diseases were reported in 6.5% of OOM and 35% of Rochester children (p < .001).
Conclusion
A high rate of B. infantis colonization, similar to that seen in developing countries, is found in the OOM at low risk for atopic diseases.
This study investigates the impact of traditional farming lifestyle on infant gut microbiome. Infant stool and milk sample analyses of microbiome composition and fatty acids concentrations were perfomed in a cohort of Old Order Mennonite infants at low risk and Rochester urban/suburban infants at high risk for atopic diseases. Microbiome of Old Order Mennonite infants is enriched in B. infantis compared with Rochester infants, which may be beneficial in prevention of atopic diseases.
In addition to farming exposures in childhood, maternal farming exposures provide strong protection against allergic disease in their children; however, the effect of farming lifestyle on human milk ...(HM) composition is unknown.
This study aims to characterize the maternal immune effects of Old Order Mennonite (OOM) traditional farming lifestyle when compared with Rochester (ROC) families at higher risk for asthma and allergic diseases using HM as a proxy.
HM samples collected at median 2 months of lactation from 52 OOM and 29 ROC mothers were assayed for IgA
and IgA
antibodies, cytokines, endotoxin, HM oligosaccharides (HMOs), and targeted fatty acid (FA) metabolites. Development of early childhood atopic diseases in children by 3 years of age was assessed. In addition to group comparisons, systems level network analysis was performed to identify communities of multiple HM factors in ROC and OOM lifestyle.
HM contains IgA
and IgA
antibodies broadly recognizing food, inhalant, and bacterial antigens. OOM HM has significantly higher levels of IgA to peanut, ovalbumin, dust mites, and
as well TGF-β2, and IFN-λ3. A strong correlation occurred between maternal antibiotic use and levels of several HMOs. Path-based analysis of HMOs shows lower activity in the path involving lactoneohexaose (LNH) in the OOM as well as higher levels of lacto-
-neotetraose (LNnT) and two long-chain FAs C-18OH (stearic acid) and C-23OH (tricosanoic acid) compared with Rochester HM. OOM and Rochester milk formed five different clusters, e.g., butyrate production was associated with
,
, and
cluster. Development of atopic disease in early childhood was more common in Rochester and associated with lower levels of total IgA, IgA
to dust mite, as well as of TSLP.
Traditional, agrarian lifestyle, and antibiotic use are strong regulators of maternally derived immune and metabolic factors, which may have downstream implications for postnatal developmental programming of infant's gut microbiome and immune system.
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