The minimal replication region of the mycobacterial plasmid pAL5000 encompasses the replication origin (ori) and two tandemly organized replication genes, repA and repB, the functions of which are not clearly known. It was observed that when the repA and repB genes were expressed in Escherichia coli, a strong ori binding activity was generated in the host cells. Inactivation of repB led to a complete loss of activity, whereas inactivation of repA had a partial effect, indicating that while repB plays an important role in the process, its activity is stimulated through coexpression of repA. However, this stimulatory effect could be demonstrated only when expression of repA and that of repB were coupled. At a relatively high concentration (1,000 nM), the purified RepB protein was found to form an ori complex with low specificity, which was sensitive to high salt concentrations and challenge by a nonspecific competitor. In contrast, the complex formed by an extract of repA-repB-expressing cells was highly specific and was resistant to both types of challenges. At a 10-fold-lower concentration, RepB did not exhibit ori binding activity, but it could nevertheless form a salt-resistant ori complex in vitro, provided that host factors were present. Antibody supershift experiments indicated that RepB is a key component of the specific complex formed by extracts prepared from E. coli cells expressing the repA and repB genes and also from mycobacterial cells harboring pAL5000-derived vectors. The results indicate that in vivo RepB interacts with host factors and forms an ori complex, but this activity is maximal only when there is coupled expression of repA.
The digha is located at the border of West Bengal and Orissa state. It has both fresh and saline waterbodies rich in aquatic vegetation and several kinds of birds in the harbours in all the seasons. Grassland areas, rice fields, herbs, shrubs and trees located in and around the water bodies provide food and shelter for these birds. Total number of 86 bird species belonging to 10 orders and 35 families were recorded during the 2-year long study period. Passeriformes is the dominant order of birds. But the future of this avian fauna is in danger due to unchecked growth of tourism related hotel industry and urbanisation of the city.
Shigella is one of the most common bacterial pathogens that are isolated from patients with diarrhea. Various attempts are being made worldwide with encouraging observations; still the emergence of multidrug-resistant Shigella strains and a continuous high disease incidence imply that shigellosis is an unsolved global health problem which can probably be solved only by developing a proper vaccine and a vaccine regime for the disease. The need of the hour is to foster the development of an effective vaccine which should not only serve to improve hygiene but also should be able to curb infections by the pathogen. This goal can only be achieved by gaining proper detailed knowledge underlying Shigella pathogenesis. The analyses of the Shigella invasion proteins which have been long been targeted to be potential candidate vaccines remains an open ended problem and forms the core of this present computational study which identifies the fact that long regions in the structure of the proteins are disordered having no distinct structural conformation; multiple alignments however, did not show any conserved stretches in the disordered regions. The results probably explain the ability of these proteins to interact with multiple cellular proteins and perform a diverse array of functions leading to successful pathogenesis.
Shigella is one of the most common bacterial pathogens that are isolated from patients with diarrhea. Various attempts are being made worldwide with encouraging observations; still the emergence of multidrug-resistant Shigella strains and a continuous high disease incidence imply that shigellosis is an unsolved global health problem which can probably be solved only by developing a proper vaccine and a vaccine regime for the disease. The need of the hour is to foster the development of an effective vaccine which should not only serve to improve hygiene but also should be able to curb infections by the pathogen. This goal can only be achieved by gaining proper detailed knowledge underlying Shigella pathogenesis. The analyses of the Shigella invasion proteins which have been long been targeted to be potential candidate vaccines remains an open ended problem and forms the core of this present computational study which identifies the fact that long regions in the structure of the proteins are disordered having no distinct structural conformation; multiple alignments however, did not show any conserved stretches in the disordered regions. The results probably explain the ability of these proteins to interact with multiple cellular proteins and perform a diverse array of functions leading to successful pathogenesis.
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