The extracellular contractile injection system is enriched in environmental microbes and associates with numerous toxins.

The extracellular Contractile Injection System (eCIS) is a toxin-delivery particle that evolved from a bacteriophage tail. Four eCISs have previously been shown to mediate interactions between bacteria and their invertebrate hosts. Here, we identify eCIS loci in 1,249 bacterial and archaeal genomes and reveal an enrichment of these loci in environmental microbes and their apparent absence from mammalian pathogens. We show that 13 eCIS-associated toxin genes from diverse microbes can inhibit the growth of bacteria and/or yeast. We identify immunity genes that protect bacteria from self-intoxication, further supporting an antibacterial role for some eCISs. We also identify previously undescribed eCIS core genes, including a conserved eCIS transcriptional regulator. Finally, we present our data through an extensive eCIS repository, termed eCIStem. Our findings support eCIS as a toxin-delivery system that is widespread among environmental prokaryotes and likely mediates antagonistic interactions with eukaryotes and other prokaryotes.

Study of Legionella Effector Domains Revealed Novel and Prevalent Phosphatidylinositol 3-Phosphate Binding Domains.

Legionella pneumophila and other Legionella species replicate intracellularly using the Icm/Dot type IV secretion system. In L. pneumophila this system translocates >300 effectors into host cells and in the Legionella genus thousands of effectors were identified, the function of most of which is unknown. Fourteen L. pneumophila effectors were previously shown to specifically bind phosphoinositides (PIs) using dedicated domains. We found that PI-binding domains of effectors are usually not homologous to one another; they are relatively small and located at the effectors' C termini. We used the previously identified Legionella effector domains (LEDs) with unknown function and the above characteristics of effector PI-binding domains to discover novel PI-binding LEDs. We identified three predicted PI-binding LEDs that are present in 14 L. pneumophila effectors and in >200 effectors in the Legionella genus. Using an in vitro protein-lipid overlay assay, we found that 11 of these L. pneumophila effectors specifically bind phosphatidylinositol 3-phosphate (PI3P), almost doubling the number of L. pneumophila effectors known to bind PIs. Further, we identified in each of these newly discovered PI3P-binding LEDs conserved, mainly positively charged, amino acids that are essential for PI3P binding. Our results indicate that Legionella effectors harbor unique domains, shared by many effectors, which directly mediate PI3P binding.

Soy allergy following early soy feeding in neonates.

UNLABELLED: B ACKGROUND:Feeding neonates with humanized milk formula in maternity hospitals may increase the prevalence of milk allergy in infants. However, prospective studies of the possible allergenic effect of very early soy-based formula feeding are lacking. OBJECTIVES: To assess the prevalence of soy allergy in infants fed soy-based formula in the first 3 days of life. METHODS: The study group included 982 healthy full-term infants born within a 7 month period at a hospital that routinely uses soy-based formula to supplement breastfeeding. In-hospital feeding was recorded and the parents were interviewed once monthly over the next 6 months regarding feeding practices and clinical symptoms suggesting soy allergy in the infant. RESULTS: Ninety-nine percent of the infants received soy-based formula supplement in hospital, and 33%-42% at home. No cases of immediate allergic reaction to soy or soy-induced enterocolitis were reported. CONCLUSIONS: The use of soy-based formula in the early neonatal period does not apparently increase the prevalence of soy allergy in infants followed for the next 6 months.