Roles of germination-specific lytic enzymes CwlJ and SleB in Bacillus anthracis.
نویسندگان
چکیده
The structural characteristics of a spore enable it to withstand stresses that typically kill a vegetative cell. Spores remain dormant until small molecule signals induce them to germinate into vegetative bacilli. Germination requires degradation of the thick cortical peptidoglycan by germination-specific lytic enzymes (GSLEs). Bacillus anthracis has four putative GSLEs, based upon sequence similarities with enzymes in other species: SleB, CwlJ1, CwlJ2, and SleL. In this study, the roles of SleB, CwlJ1, and CwlJ2 were examined. The expression levels of all three genes peak 3.5 h into sporulation. Genetic analysis revealed that, similar to other known GSLEs, none of these gene products are individually required for growth, sporulation, or triggering of germination. However, later germination events are affected in spores lacking CwlJ1 or SleB. Compared to the wild type, germinating spores without CwlJ1 suffer a delay in optical density loss and cortex peptidoglycan release. The absence of SleB also causes a delay in cortex fragment release. A double mutant lacking both SleB and CwlJ1 is completely blocked in cortex hydrolysis and progresses through outgrowth to produce colonies at a frequency 1,000-fold lower than that of the wild-type strain. A null mutation eliminating CwlJ2 has no effect on germination. High-performance liquid chromatography and mass spectroscopy analysis revealed that SleB is required for lytic transglycosylase activity. CwlJ1 also clearly participates in cortex hydrolysis, but its specific mode of action remains unclear. Understanding the lytic germination activities that naturally diminish spore resistance can lead to methods for prematurely inducing them, thus simplifying the process of treating contaminated sites.
منابع مشابه
Characterization of the germination of Bacillus megaterium spores lacking enzymes that degrade the spore cortex.
AIMS To determine roles of cortex lytic enzymes (CLEs) in Bacillus megaterium spore germination. METHODS AND RESULTS Genes for B. megaterium CLEs CwlJ and SleB were inactivated and effects of loss of one or both on germination were assessed. Loss of CwlJ or SleB did not prevent completion of germination with agents that activate the spore's germinant receptors, but loss of CwlJ slowed the rel...
متن کاملMutational analysis of Bacillus megaterium QM B1551 cortex-lytic enzymes.
Molecular-genetic and muropeptide analysis techniques have been applied to examine the function in vivo of the Bacillus megaterium QM B1551 SleB and SleL proteins. In common with Bacillus subtilis and Bacillus anthracis, the presence of anhydromuropeptides in B. megaterium germination exudates, which is indicative of lytic transglycosylase activity, is associated with an intact sleB structural ...
متن کاملCrystal structure of the catalytic domain of the Bacillus cereus SleB protein, important in cortex peptidoglycan degradation during spore germination.
The SleB protein is one of two redundant cortex-lytic enzymes (CLEs) that initiate the degradation of cortex peptidoglycan (PG), a process essential for germination of spores of Bacillus species, including Bacillus anthracis. SleB has been characterized as a soluble lytic transglycosylase that specifically recognizes spore cortex PG and catalyzes the cleavage of glycosidic bonds between N-acety...
متن کاملActivity and regulation of various forms of CwlJ, SleB, and YpeB proteins in degrading cortex peptidoglycan of spores of Bacillus species in vitro and during spore germination.
Germination of Bacillus spores requires degradation of a modified layer of peptidoglycan (PG) termed the spore cortex by two redundant cortex-lytic enzymes (CLEs), CwlJ and SleB, plus SleB's partner protein, YpeB. In this study, in vitro and in vivo analyses have been used to clarify the roles of individual SleB and YpeB domains in PG degradation. Purified mature Bacillus cereus SleB without it...
متن کاملContributions of four cortex lytic enzymes to germination of Bacillus anthracis spores.
Bacterial spores remain dormant and highly resistant to environmental stress until they germinate. Completion of germination requires the degradation of spore cortex peptidoglycan by germination-specific lytic enzymes (GSLEs). Bacillus anthracis has four GSLEs: CwlJ1, CwlJ2, SleB, and SleL. In this study, the cooperative action of all four GSLEs in vivo was investigated by combining in-frame de...
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ورودعنوان ژورنال:
- Journal of bacteriology
دوره 191 7 شماره
صفحات -
تاریخ انتشار 2009