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Infect Immun. 2000 Dec;68(12):6542-53.
Identification and characterization of the scl gene encoding a group A Streptococcus extracellular protein virulence factor with similarity to human collagen.

Lukomski S, Nakashima K, Abdi I, Cipriano VJ, Ireland RM, Reid SD, Adams GG, Musser JM.

Department of Pathology, Baylor College of Medicine, Houston, Texas 77030, USA.

Group A Streptococcus (GAS) expresses cell surface proteins that mediate important biological functions such as resistance to phagocytosis, adherence to plasma and extracellular matrix proteins, and degradation of host proteins. An open reading frame encoding a protein of 348 amino acid residues was identified by analysis of the genome sequence available for a serotype M1 strain. The protein has an LPATGE sequence located near the carboxy terminus that matches the consensus sequence (LPXTGX) present in many gram-positive cell wall-anchored molecules. Importantly, the central region of this protein contains 50 contiguous Gly-X-X triplet amino acid motifs characteristic of the structure of human collagen. The structural gene (designated scl for streptococcal collagen-like) was present in all 50 GAS isolates tested, which together express 21 different M protein types and represent the breadth of genomic diversity in the species. DNA sequence analysis of the gene in these 50 isolates found that the number of contiguous Gly-X-X motifs ranged from 14 in serotype M6 isolates to 62 in a serotype M41 organism. M1 and M18 organisms had the identical allele, which indicates very recent horizontal gene transfer. The gene was transcribed abundantly in the logarithmic but not stationary phase of growth, a result consistent with the occurrence of a DNA sequence with substantial homology with a consensus Mga binding site immediately upstream of the scl open reading frame. Two isogenic mutant M1 strains created by nonpolar mutagenesis of the scl structural gene were not attenuated for mouse virulence as assessed by intraperitoneal inoculation. In contrast, the isogenic mutant derivative made from the M1 strain representative of the subclone most frequently causing human infections was significantly less virulent when inoculated subcutaneously into mice. In addition, both isogenic mutant strains had significantly reduced adherence to human A549 epithelial cells grown in culture. These studies identify a new extracellular GAS virulence factor that is widely distributed in the species and participates in adherence to host cells and soft tissue pathology.


online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11083763&dopt=Abstract



J Biol Chem. 2001 Feb 16;276(7):5222-7. Epub 2000 Nov 17.
Conformational dependence of collagenase (matrix metalloproteinase-1) up-regulation by elastin peptides in cultured fibroblasts.

Brassart B, Fuchs P, Huet E, Alix AJ, Wallach J, Tamburro AM, Delacoux F, Haye B, Emonard H, Hornebeck W, Debelle L.

UPRES-A CNRS 6021, IFR53 Biomolecules, Faculties of Sciences and Medicine, IFR53 Biomolecules, Faculty of Sciences, University of Reims, 51687 Reims, France.

We have established that treatment of cultured human skin fibroblasts with tropoelastin or with heterogenic peptides, obtained after organo-alkaline or leukocyte elastase hydrolysis of insoluble elastin, induces a high expression of pro-collagenase-1 (pro-matrix metalloproteinase-1 (pro-MMP-1)). The identical effect was achieved after stimulation with a VGVAPG synthetic peptide, reflecting the elastin-derived domain known to bind to the 67-kDa elastin-binding protein. This clearly indicated involvement of this receptor in the described phenomenon. This notion was further reinforced by the fact that elastin peptides-dependent MMP-1 up-regulation has not been demonstrated in cultures preincubated with 1 mm lactose, which causes shedding of the elastin-binding protein and with pertussis toxin, which blocks the elastin-binding protein-dependent signaling pathway involving G protein, phospholipase C, and protein kinase C. Moreover, we demonstrated that diverse peptides maintaining GXXPG sequences can also induce similar cellular effects as a "principal" VGVAPG ligand of the elastin receptor. Results of our biophysical studies suggest that this peculiar consensus sequence stabilizes a type VIII beta-turn in several similar, but not identical, peptides that maintain a sufficient conformation to be recognized by the elastin receptor. We have also established that GXXPG elastin-derived peptides, in addition to pro-MMP-1, cause up-regulation of pro-matrix metalloproteinase-3 (pro-stromelysin 1). Furthermore, we found that the presence of plasmin in the culture medium activated these MMP proenzymes, leading to a consequent degradation of collagen substrate. Our results may be, therefore, relevant to pathobiology of inflammation, in which elastin-derived peptides bearing the GXXPG conformation (created after leukocyte-dependent proteolysis) bind to the elastin receptor of local fibroblasts and trigger signals leading to expression and activation of MMP-1 and MMP-3, which in turn exacerbate local connective tissue damage.


online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11084020&dopt=Abstract



J Biol Chem. 2001 Feb 16;276(7):5303-9. Epub 2000 Nov 17.
Characterization of type XI collagen-glycosaminoglycan interactions.

Vaughan-Thomas A, Young RD, Phillips AC, Duance VC.

Connective Tissue Biology Laboratories, School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3US, Wales, United Kingdom. vaughan-thomaardiff.ac.uk

Using competitive binding experiments, it was found that native type XI collagen binds heparin, heparan sulfate, and dermatan sulfate. However, interactions were not evident with hyaluronic acid, keratan sulfate, or chondroitin sulfate chains over the concentration range studied. Chondrocyte-matrix interactions were investigated using cell attachment to solid phase type XI collagen. Pretreatment of chondrocytes with either heparin or heparinase significantly reduced attachment to type XI collagen. Incubation of denatured and cyanogen bromide-cleaved type XI collagen with radiolabeled heparin identified sites of interaction on the alpha1(XI) and alpha2(XI) chains. NH(2)-terminal sequence data confirmed that the predominant heparin-binding peptide contained the sequence GKPGPRGQRGPTGPRGSRGAR from the alpha1(XI) chain. Using rotary shadowing electron microscopy of native type XI collagen molecules and heparin-bovine serum albumin conjugate, an additional binding site was identified at one end of the triple helical region of the collagen molecule. This coincides with consensus heparin binding motifs present at the amino-terminal ends of both the alpha1(XI) and the alpha2(XI) chains. The contribution of glycosaminoglycan-type XI collagen interactions to cartilage matrix stabilization is discussed.


online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11084037&dopt=Abstract



J Biol Chem. 2001 Mar 2;276(9):6083-92. Epub 2000 Nov 17.
Mutations in cartilage oligomeric matrix protein causing pseudoachondroplasia and multiple epiphyseal dysplasia affect binding of calcium and collagen I, II, and IX.

Thur J, Rosenberg K, Nitsche DP, Pihlajamaa T, Ala-Kokko L, Heinegard D, Paulsson M, Maurer P.

Institute for Biochemistry, Medical Faculty, University of Cologne, D-50931 Koln, Germany.

Mutations in type 3 repeats of cartilage oligomeric matrix protein (COMP) cause two skeletal dysplasias, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED). We expressed recombinant wild-type COMP that showed structural and functional properties identical to COMP isolated from cartilage. A fragment encompassing the eight type 3 repeats binds 14 calcium ions with moderate affinity and high cooperativity and presumably forms one large disulfide-bonded folding unit. A recombinant PSACH mutant COMP in which Asp-469 was deleted (D469 Delta) and a MED mutant COMP in which Asp-361 was substituted by Tyr (D361Y) were both secreted into the cell culture medium of human cells. Circular dichroism spectroscopy revealed only small changes in the secondary structures of D469 Delta and D361Y, demonstrating that the mutations do not dramatically affect the folding and stability of COMP. However, the local conformations of the type 3 repeats were disturbed, and the number of bound calcium ions was reduced to 10 and 8, respectively. In addition to collagen I and II, collagen IX also binds to COMP with high affinity. The PSACH and MED mutations reduce the binding to collagens I, II, and IX and result in an altered zinc dependence. These interactions may contribute to the development of the patient phenotypes and may explain why MED can also be caused by mutations in collagen IX genes.


online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11084047&dopt=Abstract



Arch Oral Biol. 2000 Dec;45(12):1049-57.
Effects of tensile forces on the expression of type III collagen in rat interparietal suture.

Tanaka E, Miyawaki Y, Tanaka M, Watanabe M, Lee K, del Pozo R, Tanne K.

Department of Orthodontics, Hiroshima University School of Dentistry, 1-2-3 Kasumi, Minami-ku, 734-8553, Hiroshima, Japan.

The aim was to investigate the direct contribution of mechanically induced stress to synthesized type III collagen in the interparietal suture. Twenty 4-week-old male rats were used as experimental animals. An activated expansion spring was placed across the interparietal suture. After expansion, the parietal bones including the suture were dissected and immunostained for type I and III collagens. Also, a three-dimensional model of the interparietal suture was developed to analyze stress during expansion. The localization of type III collagen in the suture was dependent upon the duration of expansion. Although the control suture exhibited no or little reactivity for type III collagen, it was observed as early as 15 h of expansion in the cambial layers, and was distributed throughout the suture at 50 h of expansion. The time-dependent distribution of type III collagen was fully consistent with that of tensile stresses calculated by the use of a three-dimensional finite-element model. It was concluded that the increases in tensile stress are associated with the synthesis of type III collagen in the suture.


online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11084144&dopt=Abstract







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