The Linker Region Promotes Activity and Binding Efficiency of Modular LPMO towards Polymeric Substrate.

Lytic polysaccharide monooxygenases (LPMOs) mediate oxidative degradation of plant polysaccharides. The genes encoding LPMOs are most commonly arranged with one catalytic domain, while a few are found tethered to additional noncatalytic units, i.e., cellulase linker and carbohydrate-binding module (CBM). The presence of CBM is known to facilitate catalysis by directing the enzymes toward cellulosic polymer, while the role of linkers is poorly understood. Based on limited experimental evidence, linkers are believed to serve merely as flexible spacers between the structured domains. Thus, this study aims to unravel the role of the linker regions present in LPMO sequences. For this, we analyzed the genome of Botrytis cinerea and found 9 genes encoding cellulose lytic monooxygenases (AA9 family), of which BcAA9C was overexpressed in cellulose-inducible conditions. We designed variants of flLPMO (full-length enzyme) with truncation of either linker or CBM to examine the role of linker in activity, binding, and thermal stability of the associated monooxygenase. Biochemical assays predicted that the deletion of linker does not impact the potential of flLPMO for catalyzing the oxidation of Amplex Red, but that it does have a major influence on the capability of flLPMO to degrade recalcitrant polysaccharide substrate. Langmuir isotherm and SEM analysis demonstrated that linker domain aids in polysaccharide binding during flLPMO-mediated deconstruction of plant cell wall. Interestingly, linker domain was also found to contribute toward the thermostability of flLPMO. Overall, our study reveals that linker is not merely a spacer, but plays a key role in LPMO-mediated biomass fibrillation; these findings are broadly applicable to other polysaccharide-degrading enzymes. IMPORTANCE The polysaccharide-disintegrating carbohydrate-active enzymes (CAZymes) are often found with multimodular architecture, where the catalytic domain is connected to an accessory CBM domain with the help of a flexible linker region. So far, the linker has been understood merely as a flexible spacer between the two domains. Therefore, the current study is designed to determine the role of linker in polysaccharide fibrillation. To conceive this study, we have selected LPMO as a model enzyme, as it is not only an industrially relevant enzyme but it also harbors a catalytic domain, linker region, and CBM domain. The present study highlighted the crucial and indispensable role of the linker region in mediating polysaccharide disintegration. Considering its role in binding, thermostability, and activity toward polysaccharide substrate, we propose linker as a potential candidate for future CAZyme engineering.

Quantification of genetic variability and stable genotype selection over the years in the germplasm of critically endangered Prishanparni (Uraria picta Desv.).

Prishanparni (Uraria picta Desv.), a critically endangered annual shrub belonging to the family 'Papillionaceae'. It is widely distributed throughout India, Sri Lanka, Bangladesh, Tropical Africa, Malay Islands, and the Philippines. The consistent performances of U. picta accessions based on ten economic traits studied were identified as P-12, P-16, P-21, P-22, P-31, P-47, and P-48. These accessions could be used for commercial cultivation in northern Indian plains. Among the total twenty-three studied accessions P-50, P-21, P-48, and P-47 were found superior for rhoifolin content in their aerial as well as root part, which may have various therapeutic potentials used in traditional and modern systems of medicines. These accessions can be exploited for commercial cultivation or in a hybridization program for further crop improvement. Wide range cultivation of the selected accessions in the Indo-Gangetic plains will fit in the existing cropping systems of this region, resulting in comparatively better supplementation of herb to the pharmaceutical and herbal drug industries and reducing the pressure on the wild populations.

A Study of Magnitude and Psychological Correlates of Smartphone Use in Medical Students: A Pilot Study with A Novel Telemetric Approach.

CONTEXT: Smartphone use is being investigated as a potential behavioral addiction. Most of the studies opt for a subjective questionnaire-based method. This study evaluates the psychological correlates of excessive smartphone use. It uses a telemetric approach to quantitatively and objectively measure participants' smartphone use. METHODOLOGY: One hundred forty consenting undergraduate and postgraduate students using an Android smartphone at a tertiary care teaching hospital were recruited by serial sampling. They were pre-tested with the Smartphone Addiction Scale-Short Version, Big five inventory, Levenson's Locus of Control Scale, Ego Resiliency Scale, Perceived Stress Scale, and Materialism Values Scale. Participants' smartphones were installed with tracker apps, which kept track of total smartphone usage and time spent on individual apps, number of lock-unlock cycles, and total screen time. Data from tracker apps were recorded after 7 days. RESULTS: About 36 % of participants fulfilled smartphone addiction criteria. Smartphone Addiction Scale score significantly predicted time spent on a smartphone in the 7-day period (ß = 0.234, t = 2.086, P = 0.039). Predictors for time spent on social networking sites were ego resiliency (ß = 0.256, t = 2.278, P = 0.008), conscientiousness (ß = -0.220, t = -2.307, P = 0.023), neuroticism (ß = -0.196, t = -2.037, P = 0.044), and openness (ß = -0.225, t = -2.349, P = 0.020). Time spent gaming was predicted by success domain of materialism (ß =0.265, t = 2.723, P = 0.007) and shopping by ego resiliency and happiness domain of materialism. CONCLUSIONS: Telemetric approach is a sound, objective method for evaluating smartphone use. Psychological factors predict overall smartphone usage as well as usage of individual apps. Smartphone Addiction Scale scores correlate with and predict overall smartphone usage.