Relation between inhibition of Bacilli sporulation and synthesis of lytic enzymes

Netropsin inhibits the increase of intracellular Ca(2+)-dependent serine proteinase activity in sporulating Bacillus megaterium

Netropsin suppressed the increase of intracellular proteolytic activity when added to B. megaterium incubated in a sporulation medium. The inhibited enzyme was a Ca(2+)-dependent serine proteinase. Sporulation and protein turnover in later sporulation phases were inhibited as well. Different concentrations of netropsin affected various aspects of protein catabolism differently.

Stimulation of the onset of sporulation of Clostridium perfringens type A by netropsin and distamycin

The basic peptide antibiotics, netropsin and distamycin, previously shown to inhibit sporulation of Bacillus subtilis, stimulated low levels of sporulation of Clostridium perfringens strain NCTC 8798 at concentrations of 1.0 and 0.1 microgram/ml respectively. Most sporulating cells produced in the presence of the antibiotics were defective. These were blocked at Stage III of sporulation, and many possessed forespores exterior to the sporangium. The same antibiotics could also inhibit the caffeine-induced stimulation of sporulation of this strain.

Purification and partial characterization of the gamma-D-glutamyl-L-di-amino acid endopeptidase II from Bacillus sphaericus

1. A gamma-D-glutamyl-L-di-amino acid endopeptidase II (EC3.4.-.-) active on the peptide moieties of some bacterial peptidoglycans has been purified to homogeneity from the sporulation medium and from the spores of Bacillus sphaericus. 2. Enzyme from both sources showed a single protein band (Mr 28,000) by polyacrylamide gel electrophoresis under denaturing conditions. It is an acidic protein (pI 4.1). Kinetic studies have shown a Km value of 0.24 mM and an apparent Vmax of 8.3 mumol min-1 mg-1 with the pentapeptide L-Ala-gamma-D-Glu-L-Lys-D-[14C]Ala-D-[14C]Ala as substrate. 3. The enzyme was inhibited by p-hydroxymercuribenzoate, a sulfhydryl inhibitor. 4. The 38-residue N-terminal region was sequenced. It may be useful to construct a nucleotide probe for the research of the gene encoding this enzyme.

Purification and partial characterization of the extracellular gamma-D-glutamyl-(L)meso-diaminopimelate endopeptidase I, from Bacillus sphaericus NCTC 9602

The gamma-D-glutamyl-(L)meso-diaminopimelate endopeptidase, or endopeptidase I, from Bacillus sphaericus 9602 was purified to apparent protein homogeneity. The purification was achieved by a six-step procedure: ammonium sulfate fractionation, phenyl-Sepharose chromatography, two consecutive DEAE-Trisacryl chromatographies, chromatofocusing and Sephacryl S-200 permeation chromatography. The enzyme was purified 5000-fold with a 38% recovery of lytic activity. It is an acidic protein (pI 5.4) of hydrophobic nature. Kinetic studies have shown a Km value of 0.57 mM and an apparent Vmax of 8.3 mumol min-1 (mg enzyme)-1 with N-acetylmuramyl-L-alanyl-gamma-D-glutamyl-(L)meso-diaminopimelyl (L)-D-[14C]alanine as substrate. The enzyme was inhibited by o-phenanthroline and EDTA and was reactivated by zinc, cobalt and manganese ions; thus endopeptidase I is a metallo enzyme, probably a zinc enzyme. Moreover it is a heat-stable protein with an apparent inactivation temperature of 80 degrees C.

Monovalent cations enable cell wall turnover of the turnover-deficient lyt-15 mutant of Bacillus subtilis

A lyt-15 mutant reported to be unable to turn over the cell wall exhibited the same rate of wall turnover as the standard strain if the medium contained 0.2 M NaCl, which did not affect growth. Cell wall autolysis was also optimal at 0.2 M NaCl.

Enzymatic preparation of an immunostimulant, the disaccharide-dipeptide, N-acetyl-beta-D-glucosaminyl-(1----4)-N-acetylmuramyl-L-alanyl-D-is ogl utamine, from a bacterial peptidoglycan

The disaccharide-dipeptide N-acetyl-beta-D-glucosaminyl-(1----4)-N-acetylmuramyl-L-alanyl-D-isog lut amine has been obtained by an enzymatic degradation of the peptidoglycan of Actinomadura R39. The peptidoglycan was hydrolyzed successively by the three following enzymes: lysozyme, DD-carboxypeptidase from Streptomyces albus G and gamma-D-glutamyl-meso-diaminopimelate endopeptidase I from Bacillus sphaericus 9602. The by-products of the last reaction were eliminated by successive ion-exchange and gel-permeation chromatographies. Both chemical analysis and mass spectrometry show that the resulting disaccharide-dipeptide is a pure compound.

Influence of heat and sodium dodecyl sulfate on the endopeptidase I from Bacillus sphaericus 9602

Endopeptidase I from Bacillus sphaericus is a stable enzyme which retains its activity at 37 degrees C in the presence of sodium dodecyl sulfate. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed two forms of the enzyme: an active, fast-running form, for the enzyme preheated at 37 degrees C and a denatured, slow-running form, for the enzyme preheated at 100 degrees C. Such behavior is similar to that of the "heat-modifiable" outer membrane proteins from gram-negative bacteria. In the absence of sodium dodecyl sulfate, endopeptidase I aggregated in an enzymatically active dimer, with an apparent molecular weight of 90,000 daltons, which could be the native form of the enzyme.

[Action of Bacillus sphaericus endopeptidases on bacterial peptidoglycans and peptidoglycan fragments]

Two endopeptidases have been characterized in Bacillus sphaericus 9602: a gamma-D-glutamyl-(L) meso-diaminopimelate endopeptidase (endopeptidase I) and a gamma-D-glutamyl-L-diaminoacid endopeptidase (endopeptidase II). They are active on the peptide moieties of some bacterial peptidoglycans. Their specificities have been studied on peptides or monomeric glycopeptides derived from peptidoglycans. Their study was attempted on dimeric and polymeric fragments of a E. coli radioactive peptidoglycan. Those compounds are specifically labelled on the meso-diaminopimelate residues and are listed below.

Possible involvement of bacterial autolytic enzymes in flagellar morphogenesis

Autolytic enzymes were found to be required for flagellar morphogenesis in Bacillus subtilis 168 and Bacillus licheniformis 6346. Two previously characterized, poorly lytic, chain-forming mutants of B. subtilis 168, strains FJ3 (temperature conditional) and FJ6, each 90 to 95% deficient in the production of N-acetylmuramyl-L-alanine amidase and endo-beta-N-acetylglucosaminidase, were observed to be nonmotile at 35 degrees C in a variety of liquid and semisolid meida. In contrast, cells of the isogenic wild-type strain were motile and fully separated. Electron microscopy revealed the complete absence of flagella on the mutant cells. Similar observations were made with another poorly lytic strain of B. subtilis 168 (Nil5) and with two poorly lytic, phosphoglucomutase-deficient mutants of B. licheniformis 6346 (MH-3, MH-5). In minimal media lacking galactose (restrictive conditions), the B. licheniformis mutants failed to form flagella, or had serious abnormalities in flagellar morphogenesis and motility. Under permissive conditions, mutants FJ3 (grown at 17 degrees C) and MH-5 (grown with addend galactose) showed increased autolytic activities, grew in the dechained form, and regained their capacities to synthesize functional flagella. Examination of several classes of spontaneous revertants derived from the various mutant strains further demonstrated a close relationship between autolysin acttivity and flagellation in the two Bacillus spp.