The Bacterial Type III Secretion System as a Target for Developing New Antibiotics

Antibiotic resistance in pathogens requires new targets for developing novel antibacterials. The bacterial type III secretion system (T3SS) is an attractive target for developing antibacterials as it is essential in the pathogenesis of many Gram-negative bacteria. The T3SS consists of structural proteins, effectors and chaperones. Over 20 different structural proteins assemble into a complex nanoinjector that punctures a hole on the eukaryotic cell membrane to allow the delivery of effectors directly into the host cell cytoplasm. Defects in the assembly and function of the T3SS render bacteria non-infective. Two major classes of small molecules, salicylidene acylhydrazides and thiazolidinones, have been shown to inhibit multiple genera of bacteria through the T3SS. Many additional chemically and structurally diverse classes of small molecule inhibitors of the T3SS have been identified as well. While specific targets within the T3SS of a few inhibitors have been suggested, the vast majority of specific protein targets within the T3SS remain to be identified or characterized. Other T3SS inhibitors include polymers, proteins and polypeptides mimics. In addition, T3SS activity is regulated by its interaction with biologically relevant molecules, such as bile salts and sterols, which could serve as scaffolds for drug design

Selected Private Higher Educational Institutions In Metro Manila: A DEA Efficiency Measurement

This paper measures the technical efficiency of 16 selected colleges and universities in Metro Manila, Philippines, using academic data for the SY 2001 – 2005. Using the data envelopment analysis (DEA), on average, schools posted 0.807 index score and need additional 19.3% efficiency growth to be efficient. Overall, there are top four efficient schools, with an average technical efficiency score between 99-100%, representing 25% of the sample. The slacks and efficient targets results have school’s policy decision-making implications: Through DEA, schools have a reference set of actual values and accurate information for performance improvement on their resource allocation usage and output targets. The benchmarking characteristics of DEA may help school’s administrators aspire for better performance by learning from other efficient schools. 

The LcrG tip chaperone protein of the Yersinia pestis type III secretion system is partially folded

The type III secretion system (T3SS) is essential in the pathogenesis of Yersinia pestis, the causative agent of plague. A small protein, LcrG, functions as a chaperone to the tip protein LcrV, and the LcrG-LcrV interaction is important in regulating protein secretion through the T3SS. The atomic structure of the LcrG family is currently unknown. However, because of its predicted helical propensity, many have suggested that the LcrG family forms a coiled-coil structure. Here, we show by NMR and CD spectroscopy that LcrG lacks a tertiary structure and it consists of three partially folded alpha helices spanning residues 7-38, 41-46, and 58-73. NMR titrations of LcrG with LcrV show that the entire length of a truncated LcrG (residues 7-73) is involved in binding to LcrV. However, there is regional variation in how LcrG binds to LcrV. The C-terminal region of a truncated LcrG (residues 52-73) shows tight-binding interaction with LcrV while the N-terminal region (residues 7-51) shows weaker interaction with LcrV. This suggests there are at least two binding events when LcrG binds to LcrV. Biological assays and mutagenesis indicate that the C-terminal region of LcrG (residues 52-73) is important in blocking protein secretion through the T3SS. Our results reveal structural and mechanistic insights into the atomic conformation of LcrG and how it binds to LcrV

NMR characterization of the interaction of the Salmonella type III secretion system protein SipD and bile salts

Salmonella and Shigella bacteria require the type III secretion system (T3SS) to inject virulence proteins into their hosts and initiate infections. The tip proteins SipD and IpaD are critical components of the Salmonella and Shigella T3SS, respectively. Recently, SipD and IpaD have been shown to interact with bile salts, which are enriched in the intestines, and are hypothesized to act as environmental sensors for these enteric pathogens. Bile salts activate the Shigella T3SS but repress the Salmonella T3SS, and the mechanism of this differing response to bile salts is poorly understood. Further, how SipD binds to bile salts is currently unknown. Computer modeling predicted that IpaD binds the bile salt deoxycholate in a cleft formed by the N-terminal domain and the long central coiled coil of IpaD. Here, we used NMR methods to determine which SipD residues are affected by the interaction with the bile salts deoxycholate, chenodeoxycholate and taurodeoxcholate. The bile salts perturbed nearly the same set of SipD residues, however, the largest chemical shift perturbations occurred away from what was predicted for the bile salt binding site in IpaD. Our NMR results indicate that that bile salt interaction of SipD will be different from what was predicted for IpaD, suggesting a possible mechanism for the differing response of Salmonella and Shigella to bile salts

Global compliance with hepatitis b vaccine birth dose and factors related to timely schedule. A literature review

Objectives: Identify global barriers for delivery of hepatitis B vaccine birth dose. Methods: A search for cross sectional studies published between January 2001 and December 2017 was conducted using the following Mesh terms: "Vaccination"[Mesh], "Mass Vaccination"[Mesh], "Hepatitis B"[Mesh], "Hepatitis B virus"[Mesh], "Hepatitis B Surface Antigens"[Mesh]. Databases consulted included: PUBMED, SCIELO, EMBASE and BIREME. To evaluate the quality of studies, we used an adapted version of the Newcastle-Ottawa Quality Assessment Scale for cross sectional studies. Results: An initial list of 6,789 articles were generated by the combination of search terms. After reviewing titles and abstracts, they were reduced to 134 for full reading, and 22 studies were included in the barriers analysis. The region with more references was Western Pacific while eastern Mediterranean had the lowest. Being born outside of a health facility and weakness of outreach vaccination service seems to be the most important an cited factors related to underperformance of birth dose delivery. In developed countries, hospital policies on birth dose vaccination was the main factor associated to no vaccintion with the birth dose. Conclusions: New ways to deliver hepatitis B vaccines to neonates being born at home or outside health facilities should be envisaged and applied, if the goal of eliminating perinatal transmission of hepatitis B is to be achieved

Identification of a new small ubiquitin-like modifier (SUMO)-interacting motif in the E3 ligase PIASy

Small ubiquitin-like modifier (SUMO) conjugation is a reversible post-translational modification process implicated in the regulation of gene transcription, DNA repair, and cell cycle. SUMOylation depends on the sequential activities of E1 activating, E2 conjugating, and E3 ligating enzymes. SUMO E3 ligases enhance transfer of SUMO from the charged E2 enzyme to the substrate. We have previously identified PIASy, a member of the Siz/protein inhibitor of activated STAT (PIAS) RING family of SUMO E3 ligases, as essential for mitotic chromosomal SUMOylation in frog egg extracts and demonstrated that it can mediate effective SUMOylation. To address how PIASy catalyzes SUMOylation, we examined various truncations of PIASy for their ability to mediate SUMOylation. Using NMR chemical shift mapping and mutagenesis, we identified a new SUMO-interacting motif (SIM) in PIASy. The new SIM and the currently known SIM are both located at the C terminus of PIASy, and both are required for the full ligase activity of PIASy. Our results provide novel insights into the mechanism of PIASy-mediated SUMOylation. PIASy adds to the growing list of SUMO E3 ligases containing multiple SIMs that play important roles in the E3 ligase activity

PORK QUALITY ASSESSMENT THROUGH IMAGE SEGMENTATION AND SUPPORT VECTOR MACHINE IMPLEMENTATION

Pork is the most consumed meat in the Philippines, and efficient quality control is essential for ensuring the safety of its consumers. Current manual procedures of meat inspection are time-consuming and laboratory-intensive considering the large amount of supply to be examined. This research aims to construct a rapid objective system of pork quality assessment with respect to meat freshness through Support Vector Machine (SVM) implementation, and to ultimately have an accuracy rate of ≥ 90%. 35 meat samples were collected, and their images were acquired. 30 of these were randomly designated as part of the training dataset while the rest were designated as part of the testing dataset. Of the 30 training samples, 6 were randomly chosen for the creation of a microbial profile. In all of the acquired image samples, image segmentation was performed and the RGB, HSV, Lab, and statistical texture features were extracted. These were inputted in 15 different SVM configurations. SVM classification yielded an accuracy rate of 93.33 %. Results from the microbial profile revealed considerable microbial activity at the 5th and 6th intervals (10th and 12th hour) with 2 and 3 colonies formed, respectively. With the ability of the SVM to distinguish between samples with respect to the hour interval and with the supplementation of the microbial profile, an objective artificial intelligence mechanism for freshness detection was successfully created.Keywords: Meat quality, Image segmentation, Support vector machine, Artificial intelligenc