Molecular modeling and functional characterization of a pertinent enzyme in <i style="mso-bidi-font-style:normal">Streptococcus pneumoniae</i> serotype-2: A potential target for the development of novel pneumonia drug

40-45Streptococcus pneumoniae is the causative agent of Pneumonia resulting in a substantial portion of childhood deaths in Bangladesh. Though drugs are in sufficient availability but the emergence of multi-drug resistant varieties of S. pneumoniae has led to the search for novel drug targets. The metabolic pathways of host (<i style="mso-bidi-font-style: normal">Homo sapiens) and pathogen (S. pneumoniae serotype-2) were compared where six biochemical pathways of S. pneumonia, distinct from human pathways, were identified. These comprised of 20 unique enzymes, which being non-homologous proteins in contrast to human host proteins, can be considered as probable drug targets. Among them, the 3D structure of an uncharacterized protein molecule was built in by homology modeling and the binding pockets of protein molecule responsible for specific functions were identified. These structural and functional characterizations of the protein, unique in S. pneumoniae in host condition, made the possibility for the sophisticated rational drug design. </span

Characterization of an Endolysin Targeting Clostridioides difficile That Affects Spore Outgrowth

Clostridioides difficile is a spore-forming enteric pathogen causing life-threatening diarrhoea and colitis. Microbial disruption caused by antibiotics has been linked with susceptibility to, and transmission and relapse of, C. difficile infection. Therefore, there is an urgent need for novel therapeutics that are effective in preventing C. difficile growth, spore germination, and outgrowth. In recent years bacteriophage-derived endolysins and their derivatives show promise as a novel class of antibacterial agents. In this study, we recombinantly expressed and characterized a cell wall hydrolase (CWH) lysin from C. difficile phage, phiMMP01. The full-length CWH displayed lytic activity against selected C. difficile strains. However, removing the N-terminal cell wall binding domain, creating CWH351—656, resulted in increased and/or an expanded lytic spectrum of activity. C. difficile specificity was retained versus commensal clostridia and other bacterial species. As expected, the putative cell wall binding domain, CWH1—350, was completely inactive. We also observe the effect of CWH351—656 on preventing C. difficile spore outgrowth. Our results suggest that CWH351—656 has therapeutic potential as an antimicrobial agent against C. difficile infection

Reduced Genome of the Gut Symbiotic Bacterium Candidatus Benitsuchiphilus tojoi Provides Insight Into Its Possible Roles in Ecology and Adaptation of the Host Insect

Diverse animals, including insects, harbor microbial symbionts within their gut, body cavity, or cells. The subsocial parastrachiid stinkbug Parastrachia japonensis is well-known for its peculiar ecological and behavioral traits, including its prolonged non-feeding diapause period and maternal care of eggs/nymphs in an underground nest. P. japonensis harbors a specific bacterial symbiont within the gut cavity extracellularly, which is vertically inherited through maternal excretion of symbiont-containing white mucus. Thus far, biological roles of the symbiont in the host lifecycle has been little understood. Here we sequenced the genome of the uncultivable gut symbiont Candidatus Benitsuchiphilus tojoi. The symbiont has an 804 kb circular chromosome encoding 606 proteins and a 14.5 kb plasmid encoding 13 proteins. Phylogenetic analysis indicated that the bacterium is closely related to other obligate insect symbionts belonging to the Gammaproteobacteria, including Buchnera of aphids and Blochmannia of ants, and the most closely related to Ishikawaella, an extracellular gut symbiont of plataspid stinkbugs. These data suggested that the symbiont genome has evolved like highly reduced gamma-proteobacterial symbiont genomes reported from a variety of insects. The presence of genes involved in biosynthesis pathways for amino acids, vitamins, and cofactors in the genome implicated the symbiont as a nutritional mutualist, supplementing essential nutrients to the host. Interestingly, the symbiont's plasmid encoded genes for thiamine and carotenoid synthesis pathways, suggesting the possibility of additional functions of the symbiont for protecting the host against oxidative stress and DNA damage. Finally, possible involvement of the symbiont in uric acid metabolism during diapause is discussed.Japan Society for the Promotion of Science (JSPS) KAKENHIMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific Research (KAKENHI) [16H04722, 19H03212, JP17H06388]; JST CRESTJapan Science & Technology Agency (JST)Core Research for Evolutional Science and Technology (CREST) [JPMJCR18S7]This work was partly supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Numbers 16H04722 and 19H03212 to TK and JP17H06388 to TF, and JST CREST Grant Number JPMJCR18S7 to TK.WOS:0005366973000012-s2.0-85085620916PubMed: 3243523

Genome analysis of new Blattabacterium spp., obligatory endosymbionts of Periplaneta fuliginosa and P. japonica.

The successful adaptation of cockroaches is, in part, dependent of the activity of their obligatory endosymbionts, Blattabacterium spp., which are involved in uric acid degradation, nitrogen assimilation and nutrient provisioning. Their strategic localization, within bacteriocytes in the proximities of uric acid storage cells (urocytes), highlights their importance in the recycling of nitrogen from urea and ammonia, end-products not secreted by their host insects. In this study, we present the complete genome sequence of two new Blattabacterium spp. from Periplaneta fuliginosa (BPfu) and P. japonica (BPja), and detailed comparison with other Blattabacterium strains from different cockroach species. The genomes of BPfu and BPja show a high degree of stability as showed with for other Blattabacterium representatives, only presenting a 19-kb fragment inversion between BPja and BPfu. In fact, the phylogenomics showed BPja as an ancestor species of BPfu, BPLAN (P. americana) and BBor (Blatta orientalis), in congruence with their host cockroach phylogeny. Their functional profile is similar and closest to the omnivorous strain BBge (Blattella germanica). Interesting, BPja possesses the complete set of enzymes involved sulfate assimilatory pathway only found in BBge and BMda (Mastotermes darwiniensis). The newly sequenced genomes of BPja and BPfu emphasise the remarkable stability of Blattabacterium genomes supported by their long-term coevolution and obligatory lifestyle in their host insect

COG frequency heat map of different <i>Blattabacterium</i> strains with their pan- and core-genome, and the free-living <i>Capnocytophaga canimorsu</i>.

<p>By alphabetic order: C, energy production and conversion; D, cell cycle control; E, amino acid transport and metabolism; F, nucleotide transport and metabolism; G, carbohydrate transport and metabolism; H, coenzyme transport and metabolism; I, lipid transport and metabolism; J, translation; K, transcription; L, replication, recombination, and repair; M, cell/wall membrane biogenesis; N, cell motility; O, post-translational modification, protein turnover, chaperones; P, inorganic ion transport and metabolism; Q, secondary metabolites biosynthesis, transport, and catabolism; R, general function prediction only; S, function unknown; T, signal transduction mechanism; U, intracellular trafficking and secretion; and V, defense mechanism.</p

List of genes associated with amino acid synthesis in all sequenced <i>Blattabacterium</i> strains.

<p>The absent genes are represented by white boxes. Host species abbreviations: BPfu, <i>Periplaneta fuliginosa</i>; BPja, <i>Periplaneta japonica</i>; BNCIN, <i>Nauphoeta cinerea</i>; BGIGA, <i>Blaberus giganteus</i>; BBge, <i>Blattella germanica</i>; BPLAN, <i>Periplaneta americana</i>; BBor, <i>Blatta orientalis</i>; BPAA, <i>Panesthia angustipennis</i>; BCpu, <i>Cryptocercus punctulatus</i>; BMda, <i>Mastotermes darwiniensis</i>. Vertical bars indicate omnivorous (blue), wood-feeding (red), and litter-feeding (black) hosts, respectively. EAA are indicated by orange horizontal bars, and non-EAA indicated by black horizontal bars.</p

The pathway of sulfate assimilation from different <i>Blattabacterium</i> strains.

<p>(a). Genes required for sulfur assimilation (b) include <i>cysN</i> and <i>cysD</i> coding for two subunits of sulfate adenyltransferase; the adenosine 5’-phosphosulfate (APS) reductase <i>cysH</i> and the sulfite reductase <i>cysIJ</i>. There is a missing step for the conversion of adenosine-5'-phosphosulfate (APS) into 3'-phospho adenosine-5'-phosphosulfate (PAPS). The generated sulfite is reduced to hydrogen sulfide further on assimilated into sulfur-containing amino acids L-cysteine and L-methionine.</p

Genome analysis of new <i>Blattabacterium</i> spp., obligatory endosymbionts of <i>Periplaneta fuliginosa</i> and <i>P</i>. <i>japonica</i> - Fig 6

<p><b>Reconstruction of pathways for biosynthesis of vitamins (a) and cofactors (b) in <i>Periplaneta fuliginosa</i> and <i>P</i>. <i>japonica</i>.</b> Gene names are indicated in coloured rectangles. White rectangles indicate missing genes and circles indicate products.</p

Gene order comparison between all <i>Blattabacterium</i> strains.

<p>Lines between genomes connect orthologous genes in blue if genes are in the same orientation, or in green if they are inverted. The first gene in all strains is <i>yidC</i> (membrane protein insertase C).</p

Characterization of BPfu and BPja genomes in comparison with other published <i>Blattabacterium</i> strains.

<p>Characterization of BPfu and BPja genomes in comparison with other published <i>Blattabacterium</i> strains.</p