The Influences of Hinge Length and Composition on the Susceptibility of Human IgA to Cleavage by Diverse Bacterial IgA1 Proteases

Senior, B. W.; Woof, Jennifer M.

doi:10.4049/jimmunol.174.12.7792

Cited by 48 publications

(39 citation statements)

References 33 publications

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“…Pneumococci are known to possess several surface-associated proteases and glycosidases. These enzymes have been shown to play an important role in the degradation of host proteins (12,35,40,41). To see if the addition of apo-hLf to the growth medium of growing pneumococci would result in a degradation of apo-hLf, we incubated 2 ϫ 10 6 CFU of actively growing bacteria in 5 ml of THY containing either 0.6 M apo-hLf or holo-hLf.…”

Section: Resultsmentioning

confidence: 99%

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

et al. 2011

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It is known that apolactoferrin, the iron-free form of human lactoferrin, can kill many species of bacteria, including Streptococcus pneumoniae. Lactoferricin, an N-terminal peptide of apolactoferrin, and fragments of it are even more bactericidal than apolactoferrin. In this study we found that apolactoferrin must be cleaved by a serine protease in order for it to kill pneumococci. The serine protease inhibitors were able to block killing by apolactoferrin but did not block killing by a lactoferrin-derived peptide. Thus, the killing of pneumococci by apolactoferrin appears to require a protease to release a lactoferricin-like peptide(s). Incubation of apolactoferrin with growing pneumococci resulted in a 12-kDa reduction in its molecular mass, of which about 7 to 8 kDa of the reduction was protease dependent. Capsular type 2 and 19F strains with mutations in the gene encoding the major cell wall-associated serine protease, prtA, lost much of their ability to degrade apolactoferrin and were relatively resistant to killing by apolactoferrin (P < 0.001). Recombinant PrtA was also able to cleave apolactoferrin, reducing its mass by about 8 kDa, and greatly enhance the killing activity of the solution containing the apolactoferrin and its cleavage products. Mass spectroscopy revealed that PrtA makes a major cut between amino acids 78 and 79 of human lactoferrin, removing the N-terminal end of the molecule (about 8.6 kDa). The simplest interpretation of these data is that the mechanism by which apolactoferrin kills Streptococcus pneumoniae requires the release of a lactoferricin-like peptide(s) and that it is this peptide(s), and not the intact apolactoferrin, which kills pneumococci.Streptococcus pneumoniae is a major inhabitant of the human upper respiratory tract and can cause pneumonia, sepsis, meningitis, and otitis media (21a). Pneumococci are common inhabitants of the nasopharynx of healthy children and adults. Pneumococci can cause serious disease when they leave the nasopharynx and successfully invade the middle ear, lungs, blood, or brain (21a). Although specific antibody can mediate protection against pneumococcal infection (14, 53), there is also evidence that antibody is not necessary for immunity to colonization and that innate immunity plays a significant role (30,50,58). Moreover, the molecular mechanisms involved in the interaction of S. pneumoniae with the innate immune system are incompletely understood.Known innate immune system components that protect against bacterial infection in the upper airways include mucus flow, antibacterial proteins, such as lysozyme and lactoferrin, and antibacterial peptides, such as ␣-defensins and ␤-defensins (57). Human lactoferrin (hLf) has been reported to play a number of different roles in mammals, including immunoregulation, iron sequestration, promotion of calcium uptake, and bactericidal activity (52). The observation that pneumococcal surface protein A (PspA) specifically inhibits in vitro killing of pneumococci by apolactoferrin (apo-hLf), the iron-free for...

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Section: Resultsmentioning

confidence: 99%

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

et al. 2011

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“…Although several studies have provided a link between virulence and the expression of IgA proteases, it has been difficult to prove that such proteases are virulence factors in vivo. This is related to the fact that only human, gorilla, chimpanzee, and orangutan IgA are susceptible to the hitherto described IgA proteases (32,34,35).…”

Section: Discussionmentioning

confidence: 99%

A Novel Secreted Metalloprotease (CD2830) from Clostridium difficile Cleaves Specific Proline Sequences in LPXTG Cell Surface Proteins

Hensbergen

Klychnikov

Bakker

et al. 2014

Molecular & Cellular Proteomics

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Bacterial secreted proteins constitute a biologically important subset of proteins involved in key processes related to infection such as adhesion, colonization, and dissemination. Bacterial extracellular proteases, in particular, have attracted considerable attention, as they have been shown to be indispensable for bacterial virulence.Here, we analyzed the extracellular subproteome of Clostridium difficile and identified a hypothetical protein, CD2830, as a novel secreted metalloprotease. Following the identification of a CD2830 cleavage site in human HSP90␤, a series of synthetic peptide substrates was used to identify the favorable CD2830 cleavage motif. This motif was characterized by a high prevalence of proline residues. Intriguingly, CD2830 has a preference for cleaving Pro-Pro bonds, unique among all hitherto described proteases. Strikingly, within the C. difficile proteome two putative adhesion molecules, CD2831 and CD3246, were identified that contain multiple CD2830 cleavage sites (13 in total). We subsequently found that CD2830 efficiently cleaves CD2831 between two prolines at all predicted cleavage sites. Moreover, native CD2830, secreted by live cells, cleaves endogenous CD2831 and CD3246.These findings highlight CD2830 as a highly specific endoproteinase with a preference for proline residues Clostridium difficile is an anaerobic, Gram-positive, sporeforming bacterium. Human intake of spores occurs through the fecal-oral route. Upon leaving the stomach and becoming exposed to bile acids in the small intestine, the C. difficile spores germinate. Once germinated, the vegetative cells in the colon encounter an unreceptive environment (1). Competition with the normal flora, immune responses, gastric fluids (2), and specialized antimicrobial peptides all act against a developing infection. Moreover, the physical barrier formed by a layer of glycoproteins (mucins) covering the underlying epithelial cells forms a major hurdle for firm adhesion.Many enteric pathogens express factors that reduce competition, allow evasion of host immune responses, and promote adhesion and/or invasion of tissues. These virulence factors are located in the cell membrane or wall (controlling adhesion and protection) or are secreted (modifying the surrounding environment). The best studied virulence factors in C. difficile are the toxins TcdA and TcdB (3, 4), which cause destruction of the intestinal barrier by disrupting the epithelial actin cytoskeleton. It is speculated that the subsequent increased permeability of the intestinal epithelium leads to increased exudation of fluids, including nutritional substances. Damage to the intestinal mucosa causes the main symptoms of C. difficile infection, including pseudomembranous colitis (1).Data illustrating how C. difficile circumvents host defense mechanisms are limited. As an example, in response to attack by antimicrobial peptides, C. difficile expresses a set of genes that change the surface charge, thereby diminishing the interaction of cationic antimicrobial peptides on th...

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“…In view of a clinical application, the IgA2 isotype has other potential advantages. First, IgA1 antibodies contain an elongated heavily O-glycosylated hinge region (32), which is more susceptible to bacterial proteases than the IgA2 hinge (33). This may cause stability issues in vivo, particularly at bacterially colonized sites.…”

Section: Advantages and Disadvantages Of Iga Iso-and Allotypementioning

confidence: 99%

Characterization of a Mutated IgA2 Antibody of the m(1) Allotype against the Epidermal Growth Factor Receptor for the Recruitment of Monocytes and Macrophages

Lohse

Brunke

Derer

et al. 2012

Journal of Biological Chemistry

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Background: IgA constitutes a promising antibody isotype, which requires optimization before immunotherapeutic application. Results: P221R-mutated and wild type IgA2m(1) antibodies were similarly effective in killing tumor cells and in recruiting myeloid effector cells. Conclusion: Improved IgA antibodies constitute promising next generation antibodies for tumor therapy. Significance: These studies support the clinical development of therapeutic IgA antibodies.

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The Influences of Hinge Length and Composition on the Susceptibility of Human IgA to Cleavage by Diverse Bacterial IgA1 Proteases

Cited by 48 publications

References 33 publications

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

Serine Protease PrtA from Streptococcus pneumoniae Plays a Role in the Killing of S. pneumoniae by Apolactoferrin

A Novel Secreted Metalloprotease (CD2830) from Clostridium difficile Cleaves Specific Proline Sequences in LPXTG Cell Surface Proteins

Characterization of a Mutated IgA2 Antibody of the m(1) Allotype against the Epidermal Growth Factor Receptor for the Recruitment of Monocytes and Macrophages

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