Proteolytic bacterial

Putrefactive bacteria in general work most vigorously at a reaction very close to the neutral point. This fact no doubt underlie the method of controlling proteolytic action in Boak liquors by the addition of alkaline compounds. Wilson made a Btudy of the hydrogen-ion concentration of soak liquors in which proteolytic bacterial action was most active and found the pH valves between 5.5 and 6.0. 

To check if PemB is surface exposed, E. chrysanthemi cells were subjected to proteolysis. Treatment of the cell suspension with trypsin, proteinase K or chimotrypsin at a concentration of 0.1 to 1 mg/ml for 1 h did not cause PemB proteolysis or its liberation into the medium. Cell pre-treatment with EDTA-lysozyme, which renders the periplasmic proteins accessible to proteases, gave no effect. PemB was also resistant to proteolytic digestion in extract of cells disrupted by sonication or in a French press. Only addition of Triton X-100 (up to 0.1%) causing formation of the micelles with PemB lead to a quick proteolyis of this protein (data not shown). In another approach to analyse the PemB exposition, bacterial cells were labelled with sulfo-NHS-biotin. This compound is unable to cross membranes and biotinylation... 

The results for bacterial whole-cell analysis described here establish the utility of MALDI-FTMS for mass spectral analysis of whole-cell bacteria and (potentially) more complex single-celled organisms. The use of MALDI-measured accurate mass values combined with mass defect plots is rapid, accurate, and simpler in sample preparation then conventional liquid chromatographic methods for bacterial lipid analysis. Intact cell MALDI-FTMS bacterial lipid characterization complements the use of proteomics profiling by mass spectrometry because it relies on accurate mass measurements of chemical species that are not subject to posttranslational modification or proteolytic degradation. 

Subtilisin (Bacillus amyloliquefaciens) 1 274 27 500 Bacterial proteolytic enzyme... 

It has long been known that peptides of bacterial origin, such as N-formylat-ed oligopeptides, are potent activators of neutrophils. Bacterial protein biosynthesis is initiated by the codon AUG, which codes for polypeptide chains at the NH2 terminus to start with N-formylmethionine. However, very few mature bacterial proteins actually have this amino acid at the NH2 terminus because Af-formylmethionine is cleaved off by proteolytic processing. Sometimes just this amino acid is cleaved, but often several adjacent residues are also removed with it. These observations formed the basis for the chemical synthesis of a variety of N-formylated oligopeptides and an assessment of their ability to activate neutrophils in vitro. The most potent of these formylated peptides is TV-formylmethionyl-leucyl-phenylalanine (fMet-Leu-Phe). 

Although extensive biochemical data on both the bacterial and eukaryotic ATP-dependent proteases are available, the characterization of these proteolytic machines at atomic resolution has proven difficult, because of both the large size of these complexes and their lability to proteolysis and dissociation. No structural data at all are currently available for Lon and the mitochondrial ATP-dependent proteases. In the case of the cytosolic, membrane-integrated bacterial protease FtsH, atomic resolution data are available only for the ATPase domain (Krzywda et al. 2002 Niwa et al. 2002). In contrast, the ATP-dependent activators of the ClpAP and ClpXP proteolytic machines have so far resisted crystallization. Atomic resolution data are available only for the proteolytic component ClpP (Wang et al. 1997), and separately for a ClpX monomer (Kim and Kim 2003) and a ClpA monomer (Guo et al. 2002b). 

The bacterial protease HslVU is unique in two respects at present, it is the only ATP-dependent protease to have atomic coordinates of the full complex determined secondly, and in contrast to all other bacterial ATP-dependent proteases, it contains a proteolytic core that is related to the 20S proteolytic core of archaebacterial and eukaryotic proteasomes. The following sections summarize our understanding of HslVU biochemistry, crystallography, and enzymology and end with some speculation on the implications of these results for other ATP-dependent proteases. 

On the sequence level, HslV shows sequence similarity with the yS-subunits of arch-aebacterial and eukaryotic proteasomes. The crystal structure of E. coli HslV confirmed that individual subunits share the Ntn-hydrolase fold with Thrl at the N-terminus as the nucleophile, just as in proteasomes. Despite these similarities, there are substantial differences between bacterial HslVU and archaebacterial and eukaryotic 20S proteasomes. In contrast to HslVU, 20S proteasomes are assembled from four rings of seven subunits each, that build up a central proteolytic chamber and two flanking antechambers. 

Involvement of complement activation in the etiology of the acute byssinotic reaction could explain the pathogenic mechanism of histamine release, non-histamine-mediated bronchoconstriction, chemotaxis, endotoxin and bacterial proteolytic enzyme action. Bronchoconstriction experienced in the acute byssinotic reaction might be attributed to the combined action of C3a and C5a mediated histamine release and non-histamine mediated kinin activity. The presence of PMN in the nasal airways of byssinotics might be explained by the chemotactic action of C5a and the C567 complex. 

Bacteria represent a promising source for the production of industrial enzymes. Bacterial cellulases are an especialfy interesting case in point. Many thermophilic bacterial species produce cellulases that are stable and active at high temperature, resistant to proteolytic attack, and stable to mechanical and chemical denaturation. However, cellulase productivities in bacteria are notoriously low compared to other microbial sources. In this paper bacterial enzyme production systems will be discussed with a focus on comparisons of the productivities of known bacterial cellulase producers. In an attempt to draw conclusions concerning the regulation of cellulase synthesis in bacterial systems, a tentative model for regulation in Acidothennus cellulofyticus has been developed. 

Proteolytic cleavage of factor C3 provides two components with different effects. The reaction exposes a highly reactive thioester group in C3b, which reacts with hydroxyl or amino groups. This allows C3b to bind covalently to molecules on the bacterial surface (opsonization, right). In addition, C3b initiates a chain of reactions leading to the formation of the membrane attack complex (see below). Together with C4a and C5a (see below), the smaller product C3a promotes the inflammatory reaction and has chemotactic effects. 

That motile Shigella concentrate an ActA homologue on their surface provided a way to identify a proteolytic vinculin fragment as the homologue. Laine et al used synthetic FEFPPPPTDE as an immunogen to generate a polyclonal antibody (Ab). Microinjection of this antibody blocked Shigella motility in infected cells, and the Ab was localized to the bacterial tails. Western blots of... 

Proteolytic breakdown of the casein Bacterial or native plasmin enzymes that are resistant to heat treatment may lead to the formation of a gel. 

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