Biomedical subjects

Motoyuki Sugai

Publications and source records attributed to Motoyuki Sugai.

At least 19 recordsLinked to original sources

PubMed2026

Genomic Insights Into Multidrug-Resistant Foodborne Serratia liquefaciens Strains Carrying mcr-9 and Comparative Genomic Analysis of Novel Biosynthetic Gene Clusters.

Serratia liquefaciens is an opportunistic nosocomial pathogen with a wide range of antibiotic resistance patterns. This study reports the characterization of the first mcr-9-positive S. liquefaciens strains, 35E-19E1 and CST-066, isolated from meat products in Japan. The strains were screened for the presence of β-lactamases, plasmid-mediated mobile colistin resistance (mcr) genes, and carbapenemase-encoding genes using PCR. Antimicrobial susceptibility was tested using the broth microdilution method. The strains exhibited multidrug resistance (MDR) phenotypes to third-generation cephalosporins, cephamycin, fosfomycin, and other clinically important antimicrobials. Genomic DNA sequencing showed that the genome sizes of CST-066 and 35E-19E1 are 5,529,704 and 5,261,506 bps, respectively. mcr-9 was identified on a chromosome within a genetic environment that included the two-component system qseBC, which plays a key role in the signaling network that triggers colistin resistance in Enterobacterales. Downstream genome analysis revealed a 1695-bp eptB-like kdo2-lipid phosphoethanolamine transferase, which is involved in intrinsic polymyxin resistance mechanisms in Serratia spp. The strain 35E-19E1 carries five CRISPR-Cas enzymes that are essential for adaptive immunity in bacteria, allowing defense against invading elements. Functional analysis using subsystem technology revealed that both strains possess subsystem features responsible for invasion and adhesion within the host biomes. Genome mining using antiSMASH and BAGL4 revealed various biosynthetic gene clusters, responsible for secondary metabolite synthesis. Notably, we identified novel gene clusters, mainly nonribosomal peptide synthetases, in both the strains, indicating their potential to produce bioactive compounds. Although the presence of mcr-9 in Serratia may not be of clinical significance because of natural resistance of the strain to polymyxins, we shed light on the genomic characteristics of this MDR pathogen and the potential spread of mcr-9 among other bacterial species. The emergence of mcr-9 in drug-resistant S. liquefaciens provides significant insights, underscoring the need for increased surveillance of this pathogen.

biosynthetic gene cluster↗

PubMed2026

A subclade-associated genomic deletion encompassing vraDEH confers increased susceptibility to nisin A and bacitracin in Staphylococcus aureus CC121.

Antimicrobial peptides (AMPs) play important roles in suppressing bacterial colonization and infection, and several AMPs are used as antimicrobial agents. Conversely, bacteria possess mechanisms that confer resistance to AMPs. We previously identified clinical Staphylococcus aureus isolates lacking the vraDEH genes, which are involved in nisin and bacitracin resistance. All such isolates belonged to clonal complex (CC) 121 and exhibited increased susceptibility to nisin A and bacitracin. The absence of vraDEH was accompanied by the absence of a 35,005-bp genomic region encompassing the biofilm-associated icaRADBC genes and a histidine biosynthesis operon. In a vraDEH-positive CC121 strain, this region was flanked by two IS1181 elements, whereas in vraDEH-negative strains it was replaced by a single IS1181 element, suggesting deletion through recombination between IS elements. Analysis of publicly available genomes revealed that all strains carrying the 35-kb deletion belonged to a single phylogenetic subclade of CC121. The downstream IS1181 insertion was frequently found in CC121 strains, whereas the upstream insertion was only found in this subclade. Across the S. aureus population, IS1181 copy number and insertion sites correlated with phylogenetic relationships, suggesting that lineage-associated IS1181 insertion may contribute to the genomic deletion in S. aureus CC121.

Nisin↗

PubMed2006

Single nucleotide polymorphism in the cytolethal distending toxin B gene confers heterogeneity in the cytotoxicity of Actinobacillus actinomycetemcomitans.

Clinical Actinobacillus actinomycetemcomitans produces cytolethal distending toxin (CDT) with titers ranging from 10(2) to 10(8) U/mg. Single nucleotide polymorphism analysis of the cdt gene in clinical isolates identified a variation of a single amino acid at residue 281 of CdtB, which significantly affected CDT toxicity by modulating the chromatin-degrading activity of CdtB.

Aggregatibacter actinomycetemcomitans↗

PubMed2006

Innate defences against methicillin-resistant Staphylococcus aureus (MRSA) infection.

The innate immune system is the primary defence against bacterial infection. Among the factors involved in innate defence, anti-microbial peptides produced by humans have recently attracted attention due to their relevance to some diseases and also to the development of new chemotherapeutic agents. Staphylococcus aureus is one of the major human pathogens, causing a variety of infections from suppurative disease to food poisoning. Methicillin-resistant S. aureus (MRSA) is a clinical problem and with the recent emergence of a vancomycin-resistant strain, this will pose serious problems in the near future. In investigating the molecular biology of S. aureus infections to develop new chemotherapeutic agents against MRSA infections, knowledge of the interaction of innate anti-microbial peptides with S. aureus is important. In vitro and in vivo experiments demonstrate that exposure of S. aureus to host cells can induce the anti-microbial peptides beta-defensin-2 (hBD2), hBD3, and LL37/CAP18. The induction level of these peptides differs among strains, as does the susceptibility of the strains, with MRSA strains exhibiting lower susceptibility. In summary, the susceptibility of S. aureus strains, including MRSA strains, to components of the innate immune system varies, with the MRSA strains showing more resistance to both innate immune factors and chemotherapeutic agents.

Anti-Bacterial Agents↗

PubMed2006

Identification and molecular characterization of an N-Acetylmuraminidase, Aml, involved in Streptococcus mutans cell separation.

We previously demonstrated Streptococcus mutans produces two bacteriolytic enzymes of 100 kDa and 80 kDa (G. Yoshimura et al. Microbiol. Immunol. 48, 465-469, 2004). Here, we identified the protein sequence of these enzymes and found they come from a single gene product designated as automutanolysin (Aml). Aml has a modular design where the N-terminus contains five 13-amino-acid repeats and a C-terminal enzyme active domain. Aml selectively lyses S. mutans and S. sobrinus but no other oral streptococci. This suggests Aml possesses strong substrate specificity towards cariogenic bacteria present in the human oral cavity. Analysis of S. mutans peptidoglycan fragments released by Aml shows the enzyme is an N-acetylmuraminidase. We found Ca(2+) enhances the activity; and EGTA, EDTA and iodoacetic acid inhibit the activity. The optimum pH range for lytic activity was 6 to 7. Disruption of the aml gene in S. mutans results in the formation of a longer bacterial cell chain length that was dispersed by the addition of a low concentration of Aml. This suggests Aml is involved in S. mutans cell separation.

Amino Acid Sequence↗

PubMed2006

Actinobacillus actinomycetemcomitans outer membrane protein 100 triggers innate immunity and production of beta-defensin and the 18-kilodalton cationic antimicrobial protein through the fibronectin-integrin pathway in human gingival epithelial cells.

Antimicrobial peptides, human beta-defensin (hBD), and the 18-kDa cationic antimicrobial protein (CAP18) are components of innate immunity. These peptides have antimicrobial activity against bacteria, fungi, and viruses. Actinobacillus actinomycetemcomitans is a gram-negative facultative anaerobe implicated in the initiation of periodontitis. The innate immunity peptides have antibacterial activity against A. actinomycetemcomitans. We investigated the molecular mechanism of human gingival epithelial cells (HGEC) responding to exposure to A. actinomycetemcomitans. HGEC constitutively express hBD1 and inducibly express hBD2, hBD3, and CAP18 on exposure to A. actinomycetemcomitans. The level of expression varies among clinical isolates. In the signaling pathway for hBD2 induction by the bacterial contact, we demonstrate that the mitogen-activated protein (MAP) kinase and not the NF-kappaB transcription factor pathway is used. We found the outer membrane protein 100 (Omp100; identified by molecular mass) is the component inducing the hBD2 response. Omp100 binds to fibronectin, an extracellular matrix inducing hBD2 via the MAP kinase pathway. Anti-integrin alpha(5)beta(1), antifibronectin, genistein, and PP2 suppress the Omp100-induced expression of hBD2, suggesting that Src kinase is involved through integrin alpha(5)beta(1). The inflammatory cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6 and IL-8, produced by HGEC on contact with A. actinomycetemcomitans also stimulate expression of hBD2. Further, neutralizing antibody against TNF-alpha or IL-8 partially inhibits the induction of hBD2 on bacterial contact. Therefore, we found that the induction of the antimicrobial peptides is mediated by a direct response principally through an Omp100-fibronectin interaction, and using secondary stimulation by inflammatory cytokines induced by the bacterial exposure.

Actinobacillus Infections↗

PubMed2006

Biogenesis of the Actinobacillus actinomycetemcomitans cytolethal distending toxin holotoxin.

The cell cycle G2/M specific inhibitor cytolethal distending toxin (CDT) from Actinobacillus actinomycetemcomitans is composed of CdtA, CdtB, and CdtC coded on the cdtA, cdtB, and cdtC genes that are tandem on the chromosomal cdt locus. A. actinomycetemcomitans CdtA has the lipid binding consensus domain, the so-called "lipobox", at the N-terminal signal sequence. Using Escherichia coli carrying plasmid pTK3022, we show that the 16th residue, cysteine, of CdtA bound [3H]palmitate or [)H]glycerol. Further, posttranslational processing of the signal peptide, CdtA, was inhibited using globomycin, an inhibitor of lipoprotein-specific signal peptidase II. Fractionation and immunoblotting show the lipid-modified CdtA is present in the outer membrane. Immunoprecipitation and the pull-down assay of the CDT complex from E. coli carrying a plasmid containing cdtABC demonstrated that the CDT complex in the periplasm is composed of CdtA, CdtB, and CdtC and that the CDT complex in culture supernatant is an N-terminally truncated (36 to 43 amino acids) form of CdtA (CdtA'), CdtB, and CdtC. This suggests that CDT is present as a complex both in the periplasm and the supernatant where CdtA undergoes posttranslation processing to CdtA' in the process of biogenesis and secretion of CDT holotoxin into the culture supernatant. Site-directed mutagenesis of the 16th cysteine residue to glycine in CdtA altered localization of CdtA in the cell and reduced the amount of CDT activity in the culture supernatant. This suggests that CDT forms a complex inside the periplasm for lipid modification where posttranslational processing of CdtA plays an important role for the efficient production of CDT holotoxin into the culture supernatant.

Amino Acid Sequence↗

PubMed2005

Staphylococcus hyicus exfoliative toxins selectively digest porcine desmoglein 1.

Virulent strains of Staphylococcus hyicus can cause exudative epidermitis in pigs. The major symptom of this disease is exfoliation of the skin in the upper stratum spinosum. Exfoliation of the skin is strongly associated with exfoliative toxin including ExhA, ExhB, ExhC, ExhD, SHETA, and SHETB. Recently, genes for ExhA, ExhB, ExhC and ExhD were cloned. Exfoliative toxins produced by S. aureus have been shown to selectively cleave human or mouse desmoglein 1, a desmosomal adhesion molecule, that when inactivated results in blisters. In this study, we attempted to identify the molecular target of Exhs in porcine skin. Each of recombinant Exhs injected in the skin of pigs caused superficial epidermal blisters or crust formation. Cell surface staining of desmoglein 1, but not that of desmoglein 3, was abolished when cryosections of normal porcine skin were incubated with one of Exhs suggesting that Exh selectively degrade porcine desmoglein 1. In vitro incubation of the recombinant extracellular domains of desmoglein 1 and desmoglein 3 of human, mouse or canine origin demonstrated that only mouse desmogleins 1alpha and 1beta were cleaved by ExhA and ExhC at high concentration. Furthermore, injection of ExhA and ExhC at high concentration caused superficial blisters in neonatal mice. These findings strongly suggest that Exhs cause blister formation of porcine skin by digesting porcine desmoglein 1 in a similar fashion to exfoliative toxins from S. aureus.

Animals↗

PubMed2005

Cell wall-targeting domain of glycylglycine endopeptidase distinguishes among peptidoglycan cross-bridges.

ALE-1, a homologue of lysostaphin, is a peptidoglycan hydrolase that specifically lyses Staphylococcus aureus cell walls by cleaving the pentaglycine linkage between the peptidoglycan chains. Binding of ALE-1 to S. aureus cells through its C-terminal 92 residues, known as the targeting domain, is functionally important for staphylolytic activity. The ALE-1-targeting domain belongs to the SH3b domain family, the prokaryotic counterpart of the eukaryotic SH3 domains. The 1.75 angstroms crystal structure of the targeting domain shows an all-beta fold similar to typical SH3s but with unique features. The structure reveals patches of conserved residues among orthologous targeting domains, forming surface regions that can potentially interact with some common features of the Gram-positive cell wall. ALE-1-targeting domain binding studies employing various bacterial peptidoglycans demonstrate that the length of the interpeptide bridge, as well as the amino acid composition of the peptide, confers the maximum binding of the targeting domain to the staphylococcal peptidoglycan. Truncation of the highly conserved first 9 N-terminal residues results in loss of specificity to S. aureus cell wall-targeting, suggesting that these residues confer specificity to S. aureus cell wall.

Amino Acid Sequence↗

PubMed2005

Induction of keratinocyte migration via transactivation of the epidermal growth factor receptor by the antimicrobial peptide LL-37.

The closure of skin wounds is essential for resistance against microbial pathogens, and keratinocyte migration is an important step in skin wound healing. Cathelicidin hCAP18/LL-37 is an innate antimicrobial peptide that is expressed in the skin and acts to eliminate microbial pathogens. Because hCAP18/LL-37 is up-regulated at skin wound sites, we hypothesized that LL-37 induces keratinocyte migration. In this study, we found that 1 microg/ml LL-37 induced the maximum level of keratinocyte migration in the Boyden chamber assay. In addition, LL-37 phosphorylated the epidermal growth factor receptor (EGFR) after 10 min, which suggests that LL-37-induced keratinocyte migration occurs via EGFR transactivation. To test this assumption, we used inhibitors that block the sequential steps of EGFR transactivation, such as OSU8-1, CRM197, anti-EGFR no. 225 Ab, and AG1478. All of these inhibitors completely blocked LL-37-induced keratinocyte migration, which indicates that migration occurs via HB-EGF-mediated EGFR transactivation. Furthermore, CRM197, anti-EGFR no. 225, and AG1478 blocked the LL-37-induced phosphorylation of STAT3, and transfection with a dominant-negative mutant of STAT3 abolished LL-37-induced keratinocyte migration, indicating the involvement of the STAT3 pathway downstream of EGFR transactivation. Finally, we tested whether the suppressor of cytokine signaling (SOCS)/cytokine-inducible Src homology 2-containing protein (CIS) family of negative regulators of STAT3 regulates LL-37-induced keratinocyte migration. Transfection with SOCS1/Jak2 binding protein or SOCS3/CIS3 almost completely abolished LL-37-induced keratinocyte migration. In conclusion, LL-37 induces keratinocyte migration via heparin-binding-EGF-mediated transactivation of EGFR, and SOCS1/Jak 2 binding and SOCS3/CIS3 negatively regulate this migration. The results of this study suggest that LL-37 closes skin wounds by the induction of keratinocyte migration.

Antimicrobial Cationic Peptides↗

PubMed2005

Irsogladine maleate influences the response of gap junctional intercellular communication and IL-8 of human gingival epithelial cells following periodontopathogenic bacterial challenge.

Gingival epithelial cells first encounter periodontopathogenic bacteria and their metabolic products to produce inflammatory cytokines. Gap junctional intercellular communication (GJIC) is thought to play a critical role in cellular coordination in tissue homeostasis. Gap junctions are structured by connexins (CXs). GJIC response of gingival epithelial cells to the bacteria may be involved in the initiation of periodontal disease. Irsogladine maleate (IM) is known to enhance GJIC through cAMP. In the present study, we examined an effect of IM on GJIC response and on interleukin-8 (IL-8) levels in human gingival epithelial cells (HGEC) exposed to a periodontopathogenic bacterium, Actinobacillus actinomycetemcomitans, and its outer membrane protein (OMP) 29 in order to test the hypothesis that IM has the ability to modulate GJIC and inflammatory responses of gingival epithelial cells to periodontopathogenic bacteria. IM countered the OMP29-induced reduction of GJIC, CX43 levels and cAMP levels in HGEC. The simultaneous addition of OMP29 and dibutyryl cAMP also abrogated the repression of GJIC by OMP29. Furthermore, IM obviated the increase in IL-8 levels in HGEC stimulated by whole live A. actinomycetemcomitans and by OMP29. These findings suggest that IM counters the OMP29-induced GJIC reduction in HGEC through cAMP. IM may eliminate initial perturbation of gingival epithelial cells by regulating responses of GJIC and IL-8 to periodontopathogenic bacterial exposure.

Aggregatibacter actinomycetemcomitans↗

PubMed2005

Susceptibilities of periodontopathogenic and cariogenic bacteria to antibacterial peptides, {beta}-defensins and LL37, produced by human epithelial cells.

OBJECTIVES: Antimicrobial peptides are one of the factors involved in innate immunity. The susceptibility of periodontopathogenic and cariogenic bacteria to the major antimicrobial peptides produced by epithelia was investigated. METHODS: Synthetic antimicrobial peptides of human beta-defensin-1 (hBD1), hBD2, hBD3 and LL37 (CAP18) were evaluated for their antimicrobial activity against oral bacteria. They included Actinobacillus actinomycetemcomitans (20 strains), Porphyromonas gingivalis (6), Prevotella intermedia (7), Fusobacterium nucleatum (7), Streptococcus mutans (5), Streptococcus sobrinus (5), Streptococcus salivarius (5), Streptococcus sanguis (4), Streptococcus mitis (2) and Lactobacillus casei (1). RESULTS: Although the four peptides had bactericidal activity against all bacteria tested, the degree of antibacterial activity was variable against the different strains and species. The antibacterial activity of hBD1 was lower than that of the other peptides. Among the bacteria tested in this study, F. nucleatum was highly susceptible to hBD3 and LL37, and S. mutans was highly susceptible to hBD3. We measured the Zeta-potential, representing the net charge of whole bacteria, to study the relationship between susceptibility to cationic peptide and the net charge of the bacteria. Although we found some correlation in A. actinomycetemcomitans strains, we did not find a definite correlation with all the bacterial species. CONCLUSIONS: These results indicate that beta-defensins and LL37 have versatile antibacterial activity against oral bacteria.

Amino Acid Sequence↗

PubMed2005

New mechanisms of skin innate immunity: ASK1-mediated keratinocyte differentiation regulates the expression of beta-defensins, LL37, and TLR2.

Epidermal keratinocytes differentiate and form a multilayered epidermis, which is the primary barrier between the body and the outer environment. As the epidermis is constantly exposed to a variety of microbial pathogens, its function of resisting microbial pathogens is vital. This characteristic feature is formed during differentiation. Immunohistochemical analysis revealed that the upper epidermis of normal human skin expresses beta-defensins 1-3 and LL37. We hypothesized that epidermal keratinocytes develop an innate immune barrier based on human beta-defensins (hBD) and LL37 during differentiation. To prove this, we introduced an active form of the apoptosis signal-regulating kinase-1 (ASK1), an intracellular regulator of keratinocyte differentiation, into cultured normal human keratinocytes. Transfection of this active form, ASK1-DeltaN, significantly enhanced the expression of hBD1-3 and LL37. In addition, a p38 inhibitor abolished this induction, indicating that the ASK1-p38 cascade regulates the expression of hBD1-3 and LL37. Furthermore, the ASK1-p38 pathway also regulated the expression of Toll-like receptor (TLR)2 in keratinocytes. Contact between S. aureus and keratinocytes resulted in the phosphorylation of p38 and induced the expression of hBD2 and hBD3. Moreover, the p38 inhibitor reduced this induction. In conclusion, the ASK1-p38 cascade regulates the innate immunity of the skin by forming an immune barrier consisting of hBD, LL37, and TLR2 during epidermal differentiation.

Antimicrobial Cationic Peptides↗

PubMed2005

Bacterial toxins that modulate host cell-cycle progression.

The mammalian cell cycle is involved in many processes--such as immune responses, maintenance of epithelial barrier functions, and cellular differentiation--that affect the growth and colonization of pathogenic bacteria. Therefore it is not surprising that many bacterial pathogens manipulate the host cell cycle with respect to these functions. Cyclomodulins are a growing family of bacterial toxins and effectors that interfere with the eukaryotic cell cycle. Here, we review some of these cyclomodulins such as cytolethal distending toxins, vacuolating cytotoxin, the polyketide-derived macrolide mycolactone, cycle-inhibiting factor, cytotoxic necrotizing factors, dermonecrotic toxin, Pasteurella multocida toxin and cytotoxin-associated antigen A. We describe and compare their effects on the mammalian cell cycle and their putative role in disease, commensalism and symbiosis. We also discuss a possible link between these cyclomodulins and cancer.

Animals↗

PubMed2005

Identification and molecular characterization of an N-acetylmuramyl-L-alanine amidase Sle1 involved in cell separation of Staphylococcus aureus.

We purified a peptidoglycan hydrolase involved in cell separation from a Staphylococcus aureus atl null mutant and identified its gene. Characterization of the gene product shows a 32 kDa N-acetylmuramyl-L-alanine amidase that we designated Sle1. Analysis of peptidoglycan digests showed Sle1 preferentially cleaved N-acetylmuramyl-L-Ala bonds in dimeric cross-bridges that interlink the two murein strands in the peptidoglycan. An insertion mutation of sle1 impaired cell separation and induced S. aureus to form clusters suggesting Sle1 is involved in cell separation of S. aureus. The Sle1 mutant revealed a significant decrease in pathogenesis using an acute infection mouse model. Atl is the major autolysin of S. aureus, which has been implicated in cell separation of S. aureus. Generation of an atl/sle1 double mutant revealed that the mutant cell separation was heavily impaired suggesting that S. aureus uses two peptidoglycan hydrolases, Atl and Sle1, for cell separation. Unlike Atl, Sle1 is not directly involved in autolysis of S. aureus.

Amino Acid Motifs↗

PubMed2005

Cloning of swine desmoglein 1 and its direct proteolysis by Staphylococcus hyicus exfoliative toxins isolated from pigs with exudative epidermitis.

Exudative epidermitis (EE) is an acute, often fatal skin disease of piglets caused by Staphylococcus hyicus. Clinical and histopathological manifestations of EE are similar to those of staphylococcal scalded skin syndrome (SSSS), a human blistering skin disease, in which exfoliative toxins produced by Staphylococcus aureus digest the extracellular domains of desmoglein (Dsg) 1 and cause loss of epidermal cell-cell adhesion. The aims of this study were to isolate and characterize cDNA for full length of swine Dsg1, and to determine whether the extracellular domains of swine Dsg1 produced by baculovirus (sDsg1-His) could be digested by four isoforms of exfoliative toxin produced by S. hyicus (ExhA, ExhB, ExhC and ExhD). Nucleotide sequencing revealed that swine Dsg1 cDNA consisted of an open reading frame of 3138 bp, encoding a precursor protein of 1045 amino acids. Deduced amino acid sequence of the swine Dsg1 precursor were highly homologous to corresponding bovine, canine, human and murine sequences. Immunoadsorption assay with a secreted form of sDsg1-His revealed that sDsg1-His specifically absorbs the immunoreactivity of 10 human pemphigus foliaceus sera against swine keratinocyte cell surfaces, suggesting its proper conformation. When sDsg1-His was incubated in vitro with Exhs, all four isoforms of Exh directly digested sDsg1-His into smaller peptides, whereas removal of calcium from sDsg1-His completely inhibited its proteolysis by these four Exhs. Recognition and digestion of calcium-stabilized structure on the extracellular domains of swine Dsg1 by Exhs indicated that EE shares similar molecular pathophysiological mechanisms of intra-epidermal splitting with SSSS in humans.

Amino Acid Sequence↗

PubMed2005

Mutation analysis of the histidine residues in the glycylglycine endopeptidase ALE-1.

A novel staphylolytic enzyme, ALE-1, is a glycylglycine endopeptidase produced by Staphylococcus capitis EPK1. ALE-1 possesses seven histidines. Chemical modification studies using diethylpyrocarbonate and iodoacetic acid suggested that a histidine or tyrosine residue(s) in the molecule is important for the organism's staphylolytic activity. All of the histidine residues, one tyrosine, and one aspartic acid residue in the N-terminally truncated ALE-1 (DeltaN-term ALE-1) were systematically altered by site-directed mutagenesis, and the enzyme activities and metal contents of the variants were measured. Our studies indicated that His-150, His-200, His-231, His-233, and Asp-154 are essential for the enzyme activity of DeltaN-term ALE-1. Except for His-150 and Asp-154, all of these amino acids were located within the 38-amino-acid region conserved among 11 proteins, including 5 staphylolytic endopeptidases. Inductively coupled plasma-mass spectrometric analysis of DeltaN-term ALE-1 revealed that it contains one atom of zinc per molecule. Measurement of the zinc content of the mutant DeltaN-term ALE-1 suggested that His-150 and -233 are important for zinc binding; their loss in these variant enzymes coincided with the loss of staphylolytic activity. These results strongly suggest that ALE-1 is a novel member of zinc metalloproteases.

Amino Acid Sequence↗

PubMed2005

Clinical manifestations of staphylococcal scalded-skin syndrome depend on serotypes of exfoliative toxins.

We sought a possible correlation between the clinical manifestations of staphylococcal scalded-skin syndrome (SSSS) and the serotype of exfoliative toxins (ET) by PCR screening of the eta and etb genes in Staphylococcus aureus strains isolated from 103 patients with generalized SSSS and 95 patients with bullous impetigo. The eta gene and the etb gene were detected in, respectively, 31 (30%) and 20 (19%) episodes of generalized SSSS and 57 (60%) and 5 (5%) episodes of bullous impetigo. Both genes were detected in 52 (50%) episodes of generalized SSS and 33 (35%) episodes of bullous impetigo. To explain this link between etb and generalized SSSS, we examined the distribution of ETA- and ETB-specific antibodies in the healthy population (n = 175) and found that the anti-ETB antibody titer was lower than the anti-ETA titer. Thus, ETA is associated with bullous impetigo and ETB is associated with generalized SSSS, possibly owing to a lower titer of anti-ETB neutralizing antibodies in the general population.

Adolescent↗