|
|
|
|
|
|
Bacillus subtilis YhcR, a High-Molecular-Weight, Nonspecific Endonuclease with a Unique Domain Structure. Irina A. Oussenko, 2004.In a continuing effort to identify ribonucleases that may be involved in mRNA decay in Bacillus subtilis, fractionation of a protein extract from a triple-mutant strain that was missing three previously characterized 3'-to-5' exoribonucleases (polynucleotide phosphorylase [PNPase], RNase R, and YhaM) was undertaken . These experiments revealed the presence of a high-molecular-weight nuclease encoded by the yhcR gene that was active in the presence of Ca2+ and Mn2+ . YhcR is a sugar-nonspecific nuclease that cleaves endonucleolytically to yield nucleotide 3'-monophosphate products, similar to the well-characterized micrococcal nuclease of Staphylococcus aureus . YhcR appears to be located principally in the cell wall and is likely to be a substrate for a B . subtilis sortase . Zymogram analysis suggests that YhcR is the major Ca2+-activated nuclease of B . subtilis . In addition to having a unique overall domain structure, YhcR contains a hitherto unknown structural domain that we have named "NYD," for "new YhcR domain." TodK, a Putative Histidine Protein Kinase, Regulates Timing of Fruiting Body Morphogenesis in Myxococcus xanthus. Anders A. Rasmussen, 2003.In response to starvation, Myxococcus xanthus initiates a developmental program that results in the formation of spore-filled multicellular fruiting bodies . Fruiting body formation depends on the temporal and spatial coordination of aggregation and sporulation . These two processes are induced by the cell surface-associated C signal, with aggregation being induced after 6 h and sporulation being induced once cells have completed the aggregation process . We report the identification of TodK, a putative histidine protein kinase of two-component regulatory systems that is important for the correct timing of aggregation and sporulation . Loss of TodK function results in early aggregation and early, as well as increased levels of, sporulation . Transcription of todK decreases 10-fold in response to starvation independently of the stringent response . Loss of TodK function specifically results in increased expression of a subset of C-signal-dependent genes . Accelerated development in a todK mutant depends on the known components in the C-signal transduction pathway . TodK is not important for synthesis of the C signal . From these results we suggest that TodK is part of a signal transduction system which converges on the C-signal transduction pathway to negatively regulate aggregation, sporulation, and the expression of a subset of C-signal-dependent genes . TodK and the SdeK histidine protein kinase, which is part of a signal transduction system that converges on the C-signal transduction pathway to stimulate aggregation, sporulation, and C-signal-dependent gene expression, act in independent genetic pathways . We suggest that the signal transduction pathways defined by TodK and SdeK act in concert with the C-signal transduction pathway to control the timing of aggregation and sporulation . Vibrio cholerae Hemagglutinin/Protease Degrades Chironomid Egg Masses. Malka Halpern, 2003.Cholera is a severe diarrheal disease caused by specific serogroups of Vibrio cholerae that are pathogenic to humans . The disease does not persist in a chronic state in humans or animals . The pathogen is naturally present as a free-living organism in the environment . Recently, it was suggested that egg masses of the nonbiting midge Chironomus sp . (Diptera) harbor and serve as a nutritive source for V . cholerae, thereby providing a natural reservoir for the organism . Here we report that V . cholerae O9, O1, and O139 supernatants lysed the gelatinous matrix of the chironomid egg mass and inhibited eggs from hatching . The extracellular factor responsible for the degradation of chironomid egg masses (egg mass degrading factor) was purified from V . cholerae O9 and O139 and was identified as the major secreted hemagglutinin/protease (HA/P) of V . cholerae. The substrate in the egg mass was characterized as a glycoprotein . These findings show that HA/P plays an important role in the interaction of V . cholerae and chironomid egg masses .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
