Laboratory of Molecular Biology

About: Laboratory of Molecular Biology is a facility organization based out in Cambridge, Cambridgeshire, United Kingdom. It is known for research contribution in the topics: Gene & RNA. The organization has 19395 authors who have published 24236 publications receiving 2101480 citations.

Activities of Human Immunodeficiency Virus (HIV) Integration Protein In vitro: Specific Cleavage and Integration of HIV DNA

Abstract: Growth of human immunodeficiency virus (HIV) after infection requires the integration of a DNA copy of the viral RNA genome into a chromosome of the host. Here we present a simple in vitro system that carries out the integration reaction and the use of this system to probe the mechanism of integration. The only HIV protein necessary is the integration (IN) protein, which has been overexpressed in insect cells and then partially purified. DNA substrates are supplied as oligonucleotides that match the termini of the linear DNA product of reverse transcription. In the presence of HIV IN protein, oligonucleotide substrates are cleaved to generate the recessed 3' ends that are the precursor for integration, and the cleaved molecules are efficiently inserted into a DNA target. Analysis of reaction products reveals that HIV IN protein joins 3' ends of the viral DNA to 5' ends of cuts made by IN protein in the DNA target. We have also used this assay to characterize the sequences at the ends of the viral DNA involved in integration. The assay provides a simple screen for testing candidate inhibitors of HIV IN protein; some such inhibitors might have useful antiviral activity.

Knowledge based modelling of homologous proteins, part I: three-dimensional frameworks derived from the simultaneous superposition of multiple structures

Abstract: An approach is described for modelling the three-dimensional structure of a protein from the tertiary structures of several homologous proteins that have been determined by X-ray analysis. A method is developed for the simultaneous superposition of several protein molecules and for the calculation of an 'average structure' or 'framework'. Investigation of the convergence properties of this method, in the case of both weighted and unweighted least squares, demonstrates that both give a unique answer and the latter is robust for an homologous family of proteins. Multi-dimensional scaling is used to subgroup of the proteins with respect to structural homology. The framework calculated on the basis of the family of homologous proteins, or of an appropriate subgroup, is used to align fragments of the known protein structures of high sequence homology with the unknown. This alignment provides a basis for model building the tertiary structure. Different techniques for using the framework to model the mainchain of various globins and an immunoglobulin domain in the structurally conserved regions are investigated.

Multiple routes to astrocytic differentiation in the cns

Abstract: Ciliary neurotrophic factor (CNTF) acts instructively to switch multipotent stem cells of the CNS to an astrocytic fate. Here we show that CNTF causes activation of janus kinase-signal transducers and activators of transcription and mitogen-activated protein kinase (MAPK) pathways with differential kinetics in these cells. Inhibition studies indicate that activation of the MAPK pathway is required early in the differentiation process, whereas activation of signal transducer and activator of transcription (STAT) proteins is required for commitment to an astrocytic fate. Bone morphogenetic proteins have also been shown to cause astrocytic differentiation but do not cause STAT activation or astrocytic differentiation in fibroblast growth factor 2-expanded fetal stem cells used here. These results show that there are two distinct routes to initiate astrocytic commitment in multipotent CNS precursors.