Genetically Compromising Phospholipid Metabolism Limits Candida albicans’ Virulence

Mycopathologia - Perturbing ergosterol synthesis has been previously shown to reduce the virulence of Candida albicans. We tested the hypothesis that further altering cell membrane composition by...     

Specific Treatment Technologies for Removing Arsenic from Water

Arsenic (As) is a highly toxic metalloid found in ground and surface water. Arsenic contamination in drinking water leads to harmful effects on human health. To eliminate arsenic from drinking water, several technologies such as coagulation, adsorption, ion exchange, filtration, membrane processes, etc., have been used. In this study, three technologies were evaluated for arsenic removal. Results from batch kinetic experiments showed that iron coated sand (IOCS‐2) can remove more than 90 % of As from synthetic water. Experiments were conducted with three different pH values (6, 7, and 8) and an initial As concentration of 260 μg/L. A new material, developed in this study, namely iron coated sponge (IOCSp), was found to have a high capacity in removing both As (V) and As (III). Each gram of IOCSp adsorbed about 160 μg of As within a 9‐hour contact period of IOCSp with As solution. Low pressure nanofiltration removed more than 94 % of As from an influent containing 440 μg/L As. The applied pressure was varied from 85 to 500 kPa.     

Synthesis and anti-norovirus activity of pyranobenzopyrone compounds

During the last decade, noroviruses have gained media attention as the cause of large scale outbreaks of gastroenteritis on cruise ships, dormitories, nursing homes, etc. Although noroviruses do not multiply in food or water, they can cause large outbreaks because approximately 10-100 virions are sufficient to cause illness in a healthy adult. Recently, it was shown that the activity of acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) enzyme may be important in norovirus infection. In search of anti-noroviral agents based on the inhibition of ACAT1, we synthesized and evaluated the inhibitory activities of a class of pyranobenzopyrone molecules containing amino, pyridine, substituted quinolines, or 7,8-benzoquinoline nucleus. Three of the sixteen evaluated compounds possess ED(50) values in the low micrometer range. 2-Quinolylmethyl derivative 3A and 4-quinolylmethyl derivative 4A showed ED(50) values of 3.4 and 2.4 μM and TD(50) values of >200 and 96.4 μM, respectively. The identified active compounds are suitable for further modification for the development of anti-norovirus agents.     

In-vitro evaluation of the antimicrobial activity of Bauhinia variegata,locally known as koiralo

Bauhinia variegata, commonly known as Koiralo is considered as medicinal plant in Nepal and India. The alcoholic extract of this plant was found to have antimicrobial activity against Bacillus subtilis (ATCC 6635) Pseudomonas aeruginosa (ATCC 27853), Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus (ATCC 29213) and Vibrio cholerae. The largest zone of inhibition (18 mm) was found to be exhibited against B. subtilis. For this organism the minimum bactericidal concentration (MBC) of the crude extract was 0.39 mg/ml. The extract was found to be more effective against gram-positive than gram-negative bacteria. The antimicrobial activity of the extract was found to be decreased during purification.     

Structural-functional role of chloride in photosystem II

Chloride binding in photosystem II (PSII) is essential for photosynthetic water oxidation. However, the functional roles of chloride and possible binding sites, during oxygen evolution, remain controversial. This paper examines the functions of chloride based on its binding site revealed in the X-ray crystal structure of PSII at 1.9 ? resolution. We find that chloride depletion induces formation of a salt bridge between D2-K317 and D1-D61 that could suppress the transfer of protons to the lumen.     

First report of an endangered silurid catfish,Pterocryptis barakensis (Siluridae) from Brahmaputra drainage,North Eastern Himalayan region of India

The present communication reports an endangered catfish of the family Siluridae, Pterocryptis barakensis (Vishwanath & Sharma) for the first time outside its type locality from Brahmaputra drainage. The specimens were collected from the River Tissa, Longding district, Arunachal Pradesh foothills of Himalayan region of North East India. The current study describes morphometric and molecular characteristics of this endangered species.     

Genome-guided exploration of metabolic features of Streptomyces peucetius ATCC 27952: past,current, and prospect

Applied Microbiology and Biotechnology - Streptomyces peucetius ATCC 27952 produces two major anthracyclines, doxorubicin (DXR) and daunorubicin (DNR), which are potent chemotherapeutic agents for...     

Activity enhancement of a Bacillus circulans xylanase by introducing ion-pair interactions into an α-helix

IntroductionIt is widely accepted that ion-pair increases rigidity and thermostability. There are numerous studies on ion-pairs and thermostability, but none are available about the effect of ion-pair on the activity of enzymes. This paper studies whether an ion-pair allows flexible movement in an enzyme molecule and affects its activity.Materials and methodsIon-pairs are designed at the α-helix region of a Bacillus circulans xylanase, and they are far from the active-sites (23.85–25.15 Å). Two ion-pairing mutations are situated at the C-terminus (D151/E151-K154 ion-pairs) of the helix. One mutation is double-site (F48R-N151D), which introduces both the tertiary (R48-D151) and intra-helical (D151-K154) ion-pairs.Results and discussionAll of the mutants enhanced the catalytic efficiency against xylan (1.66–3.58 times). The double-site mutation showed a synergistic effect on the activity. Overall, the ion-pairs decreased the flexibility (increased rigidity) of the α-helix region and increased the active-site flexibility. The ion-pairs were destabilizing and surface-located; this means that the weaker destabilizing ion-pair still allows flexible movement in the active-site. There is higher mobility of the strand B4 where the active site residue E172 is located. Moreover, the residues lining the active-site cleft (strand B8) showed increased flexibility upon substrate binding.ConclusionIncrease in the activity was due to the increase in active-site flexibility and increased mobility of the residues lining the active-site cleft (strand B8).