RESUMEN
Cytoplasmic proteolysis is an indispensable process for proper function of a cell. Degradation of many intracellular proteins is initiated by ATP-dependent proteinases, which are involved in the regulation of the level of proteins with short half-lives. In addition, they remove many damaged and abnormal proteins and thus play also an important role during stress. ATP-dependent proteinases are large multi-subunit assemblies composed of proteolytic core domains and ATPase-containing regulatory domains on a single polypeptide chain or on distinct subunits, which can act as molecular chaperones. This review briefly summarizes the data about four main groups of these proteinases in bacteria (i.e. Lon, Clp family, HslUV and FtsH) and characterizes their structure, mechanism of action and properties.
Asunto(s)
Adenosina Trifosfatasas/metabolismo , Bacterias/enzimología , Proteínas de Choque Térmico/metabolismo , Serina Endopeptidasas/metabolismo , Proteasas ATP-Dependientes , Adenosina Trifosfatasas/genética , Bacterias/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Proteínas Portadoras/química , Proteínas Portadoras/metabolismo , Endopeptidasas/química , Endopeptidasas/genética , Endopeptidasas/metabolismo , Proteínas de Choque Térmico/genética , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Modelos Biológicos , Serina Endopeptidasas/genéticaRESUMEN
A rise of the intracellular serine proteinase activity (ISP) during postexponential growth of Bacillus subtilis was decreased by a temperature upshift from 35 degrees to 42 degrees C. However, the amount of both molecular forms of the major intracellular serine proteinase ISP1 determined by immunoblotting was similar at both temperatures or even slightly increased at 42 degrees C. The evolution of the ISP activity in B. megaterium showed an opposite temperature dependence, being faster during growth at 42 degrees C. The amount of immunologically detected ISP1 again did not correlate well with the enzyme activity. Moreover, most of the ISP1 molecules in cell-free extracts from B. megaterium were inactive and were activated by increasing the CaCl2 concentration up to 30 mM--unlike B. subtilis, where the enzymic activity was unaffected by Ca2+ concentration. These data suggest that the ISP1 activity in the two bacillar species during postexponential growth is regulated posttranscriptionally, but that the regulatory mechanisms differ.
Asunto(s)
Bacillus megaterium/enzimología , Bacillus subtilis/enzimología , Serina Endopeptidasas/metabolismo , Anticuerpos Antibacterianos/inmunología , Bacillus megaterium/fisiología , Bacillus subtilis/fisiología , Calcio/metabolismo , Medios de Cultivo , Citoplasma/enzimología , Electroforesis en Gel de Poliacrilamida , Activación Enzimática , Proteínas de Choque Térmico/metabolismo , Presión Osmótica , Serina Endopeptidasas/biosíntesis , Serina Endopeptidasas/inmunología , Esporas Bacterianas , TemperaturaRESUMEN
The sporicidal effect of Presept was compared with Chloramine B on the spores of Bacillus cereus. Either compound was calibrated to the same concentration of active chlorine. While a portion of spore population after 4 hrs of treatment by Chloramine germinated and started to divide in a rich nutrient medium, the optical density of the culture inoculated with spores treated by Presept did not increase even after 7 hrs when exposed to the nutrient medium. Significant morphological differences were found in either population of spores. Spores treated by Presept lost the impermeability within 3 hrs in the nutrient medium but almost no postgerminative development was observed. However, a portion of spores treated by Chloramine B developed after germination within 3 hrs into vegetative cells. It seems that Presept does not block germination and/or loss of impermeability of spores, but prevents their postgerminative development and division.