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The understanding of the 3-dimensional enzyme structure is important for the point of protein engineering and applications. Computer-based molecular modelling is a vital tool for theoretical predication of enzyme activities and finding their substrates and inhibitors. SMlipA lipase was cloned from forest soil metagenome and characterized as broad spectrum enzyme with high stability in various organic solvents. In the present study, to understand the mechanism of SMlipA lipase and to identify the key residues involved in enzyme-substrate interaction, three dimensional-computational model of SMlipA has been generated and validated for stereo-chemical and amino-acid environment quality using appropriate programs, and further validation of the active-site architecture was achieved by performing docking studies with different ligand. The three dimensional structure created here provide a new understanding of the ligand preferences and their interaction with protein. [ABSTRACT FROM AUTHOR]

The AB 5 type toxin produced by the Vibrio cholerae bacterium is the causative agent of the cholera disease. The cholera toxin (CT) has been shown to bind specifically to GM1 glycolipids on the membrane surface. This binding of CT to the membrane is the initial step in its endocytosis and has been postulated to cause significant disruption to the membrane structure. In this work, we have carried out a combination of coarse-grain and atomistic simulations to study the binding of CT to a membrane modelled as an asymmetrical GM1-DPPC bilayer. Simulation results indicate that the toxin binds to the membrane through only three of its five B subunits, in effect resulting in a tilted bound configuration. Additionally, the binding of the CT can increase the area per lipid of GM1 leaflet, which in turn can cause the membrane regions interacting with the bound subunits to experience significant bilayer thinning and lipid tail disorder across both the leaflets. [ABSTRACT FROM AUTHOR]

Abstract: Cold shock proteins perform vital functions, such as mRNA masking, coupling of transcription to translation and developmental timing and regulation, which aids in survival of microbes in cold stress. Pseudomonas fluorescens is an ecologically important bacterium which helps in plant growth promotion. Since the cold tolerant mutant of the bacterium is able to grow at the temperature ranges from 30 to 4°C, it is of interest to study the process of its survival in the extreme temperatures. Therefore, this study is focused on the three dimensional structure and molecular modeling of cold resistant protein (CRP) from P. fluorescens to predict its molecular mechanism. Investigating the structure of CRP confirmed the presence of a conserved domain characteristic of the cold shock domain (CSD) family and a single nucleotide binding domain. When 3D structure of CRP was compared with the existing cold shock proteins, major deviations were found in the loop regions connecting the β2–β3, β3–β4 and β4–β5 sheets. Docking studies showed that CRP forms a significant clamp like structure at the substrate binding cleft which stabilizes the ligand. Therefore, it can be concluded that CRP has a strong affinity for the poly thymidine (poly T) stretch and can be considered a candidate for transcription regulation. [Copyright &y& Elsevier]