Genome Sequence Analyses of Pseudomonas savastanoi pv. glycinea and Subtractive Hybridization-Based Comparative Genomics with Nine Pseudomonads

Bacterial blight, caused by Pseudomonas savastanoi pv. glycinea (Psg), is a common disease of soybean. In an effort to compare a current field isolate with one isolated in the early 1960s, the genomes of two Psg strains, race 4 and B076, were sequenced using 454 pyrosequencing. The genomes of both Psg strains share more than 4,900 highly conserved genes, indicating very low genetic diversity between Psg genomes. Though conserved, genome rearrangements and recombination events occur commonly within the two Psg genomes. When compared to each other, 437 and 163 specific genes were identified in B076 and race 4, respectively. Most specific genes are plasmid-borne, indicating that acquisition and maintenance of plasmids may represent a major mechanism to change the genetic composition of the genome and even acquire new virulence factors. Type three secretion gene clusters of Psg strains are near identical with that of P. savastanoi pv. phaseolicola (Pph) strain 1448A and they shared 20 common effector genes. Furthermore, the coronatine biosynthetic cluster is present on a large plasmid in strain B076, but not in race 4. In silico subtractive hybridization-based comparative genomic analyses with nine sequenced phytopathogenic pseudomonads identified dozens of specific islands (SIs), and revealed that the genomes of Psg strains are more similar to those belonging to the same genomospecies such as Pph 1448A than to other phytopathogenic pseudomonads. The number of highly conserved genes (core genome) among them decreased dramatically when more genomes were included in the subtraction, suggesting the diversification of pseudomonads, and further indicating the genome heterogeneity among pseudomonads. However, the number of specific genes did not change significantly, suggesting these genes are indeed specific in Psg genomes. These results reinforce the idea of a species complex of P. syringae and support the reclassification of P. syringae into different species

An insight into the sialome of Simulium guianense (DIPTERA:SIMulIIDAE), the main vector of River Blindness Disease in Brazil

<p>Abstract</p> <p>Background</p> <p>Little is known about the composition and function of the saliva in black flies such as <it>Simulium guianense</it>, the main vector of river blindness disease in Brazil. The complex salivary potion of hematophagous arthropods counteracts their host's hemostasis, inflammation, and immunity.</p> <p>Results</p> <p>Transcriptome analysis revealed ubiquitous salivary protein families--such as the Antigen-5, Yellow, Kunitz domain, and serine proteases--in the <it>S. guianense </it>sialotranscriptome. Insect-specific families were also found. About 63.4% of all secreted products revealed protein families found only in <it>Simulium</it>. Additionally, we found a novel peptide similar to kunitoxin with a structure distantly related to serine protease inhibitors. This study revealed a relative increase of transcripts of the SVEP protein family when compared with <it>Simulium vittatum </it>and <it>S. nigrimanum </it>sialotranscriptomes. We were able to extract coding sequences from 164 proteins associated with blood and sugar feeding, the majority of which were confirmed by proteome analysis.</p> <p>Conclusions</p> <p>Our results contribute to understanding the role of <it>Simulium </it>saliva in transmission of <it>Onchocerca volvulus </it>and evolution of salivary proteins in black flies. It also consists of a platform for mining novel anti-hemostatic compounds, vaccine candidates against filariasis, and immuno-epidemiologic markers of vector exposure.</p

A Deep Insight into the Sialotranscriptome of the Gulf Coast Tick, Amblyomma maculatum

Background: Saliva of blood sucking arthropods contains compounds that antagonize their hosts ’ hemostasis, which include platelet aggregation, vasoconstriction and blood clotting; saliva of these organisms also has anti-inflammatory and immunomodullatory properties. Perhaps because hosts mount an active immune response against these compounds, the diversity of these compounds is large even among related blood sucking species. Because of these properties, saliva helps blood feeding as well as help the establishment of pathogens that can be transmitted during blood feeding. Methodology/Principal Findings: We have obtained 1,626,969 reads by pyrosequencing a salivary gland cDNA library from adult females Amblyomma maculatum ticks at different times of feeding. Assembly of this data produced 72,441 sequences larger than 149 nucleotides from which 15,914 coding sequences were extracted. Of these, 5,353 had.75 % coverage to their best match in the non-redundant database from the National Center for Biotechnology information, allowing for the deposition of 4,850 sequences to GenBank. The annotated data sets are available as hyperlinked spreadsheets. Putative secreted proteins were classified in 133 families, most of which have no known function. Conclusions/Significance: This data set of proteins constitutes a mining platform for novel pharmacologically activ

Novel scabies mite serpins inhibit the three pathways of the human complement system

Scabies is a parasitic infestation of the skin by the mite Sarcoptes scabiei that causes significant morbidity worldwide, in particular within socially disadvantaged populations. In order to identify mechanisms that enable the scabies mite to evade human immune defenses, we have studied molecules associated with proteolytic systems in the mite, including two novel scabies mite serine protease inhibitors (SMSs) of the serpin superfamily. Immunohistochemical studies revealed that within mite-infected human skin SMSB4 (54 kDa) and SMSB3 (47 kDa) were both localized in the mite gut and feces. Recombinant purified SMSB3 and SMSB4 did not inhibit mite serine and cysteine proteases, but did inhibit mammalian serine proteases, such as chymotrypsin, albeit inefficiently. Detailed functional analysis revealed that both serpins interfered with all three pathways of the human complement system at different stages of their activation. SMSB4 inhibited mostly the initial and progressing steps of the cascades, while SMSB3 showed the strongest effects at the C9 level in the terminal pathway. Additive effects of both serpins were shown at the C9 level in the lectin pathway. Both SMSs were able to interfere with complement factors without protease function. A range of binding assays showed direct binding between SMSB4 and seven complement proteins (C1, properdin, MBL, C4, C3, C6 and C8), while significant binding of SMSB3 occurred exclusively to complement factors without protease function (C4, C3, C8). Direct binding was observed between SMSB4 and the complement proteases C1s and C1r. However no complex formation was observed between either mite serpin and the complement serine proteases C1r, C1s, MASP-1, MASP-2 and MASP-3. No catalytic inhibition by either serpin was observed for any of these enzymes. In summary, the SMSs were acting at several levels mediating overall inhibition of the complement system and thus we propose that they may protect scabies mites from complement-mediated gut damage