Mutan structure

The most common oral condition and dental emergency is dental caries, which is a destructive disease of the hard tissues of the teeth due to bacterial infection with Streptococcus mutans and other bacteria. It is characterized by destruction of enamel and dentine. Dental decay presents as opaque white areas of enamel with grey undertones and in more advanced cases, brownish discoloured cavitations. Dental caries is initially asymptomatic and pain does not occur until the decay impinges on the pulp, and an inflammation develops. Treatment of caries involves removal of the softened and infected hard tissues, sealing of exposed dentines and restoration of the lost tooth structure with porcelain, silver, amalgam, composite plastic, gold etc. 

The products are those produced by Leuc. mesenteroides B-512F dextransucrase unless otherwise indicated. b The starred products are also acceptors that give a homologous series with a-isomalto-oligosaccharides attached to the acceptor.r Structure not determined.d Two products are formed by Leuc. mesenteroides B-512F dextransucrase. Not an acceptor. Four products are formed by Strep, mutans GTF-I. Product formed by altemansucrase. 

Shimamura A, Nakano YJ, Mukasa H, Kuramitsu HK (1994) Identification of amino acid residues in Streptococcus mutans glucosyltransferases influencing the structure of the glucan product. J Bacteriol 176 4845 -850... 

In addition to the ferritin from L. innocua already mentioned, a variety of proteins show structures and iron assimilation activities similar to Dps, although they do not bind DNA. These include the Dpr (Dps-like peroxide resistance) protein from Streptococcus mutans, Dip from Bacillus anthracis and the neutrophil-activating protein from Helicobacter pylori, HP-NAP. ... 

Some other bacteria, e.g., Leuconostoc mesenteraides, make 1,6-linked poly-o-glucose or dextrans. These always contain some a-l,3-linked branches and may also have a-1,4 and a-1,2 linkages, the structures varying from species to species. Dextrans formed by bacteria such as Streptococcus mutans growing on the surfaces of teeth are an important component of dental plaque. Bacterial... 

Leuconostoc mesenteroides (4 3), Pseudomonas aeruginosa (4 4), Streptococcus mutans (435), and Bacillus stearothermophilus (486,437). The protein from the latter species was purified by Kolb and Harris (436) and found to have a free N-terminus in contrast to the liver and yeast alcohol dehydrogenases. The bacterial protein was, therefore, submitted to sequence analysis in an automatic sequenator which revealed the 45 first residues (IS). These are listed in Table XIV. It is clear that the structure of the bacterial enzyme is distantly related to those of the yeast and mammalian enzymes, but few residues are identical in all proteins at equivalent positions (Table XIV). Further aspects of this relationship are discussed in Section II,D. 

Biochem. Tokyo) 78, 225. Structural Determination of Glucans from Streptococcus Mutans JC-2(I)ental Caries Bacterium) by Carbon-13 Nuclear Magnetic Resonance. III. 

Electron-microscope observations and chemical analyses of Streptococcus mutans OMZ 176 dextran indicated that the gel formed by this water-insoluble dextran is composed of two distinct networks, one formed by association of (l->3)-linked chain segments [structures 26 (p. 393) and 38 (p. 3 )], and the other by association of (l->6)-linked chain segments [structures 6 (p. 386) and 36 (p. 396)]. It remains to be determined whether this and similar gels are formed from a single polysaccharide type (and are, therefore, continuous), or from at least two different polysaccharides. 

Most streptocci that elaborate dextransucrases appear to secrete the enzyme(s) exocellularly, although some strains of Streptococcus mutans also elaborate structure-bound forms of the enzyme. The structure-bound enzyme activities of S. mutans may be situated at several points on the outer smface of the cell wall." Evidence has also been presented that suggests that the proportions of the structure-bound and secreted forms of the enzyme produced by individual streptococci may drange with repeated subculturing of the bacteria." Similar changes have not been detected in Leuconostoc strains. ... 

McCabe and Smith" have observed that the cell-associated dextransucrase elaborated by S. mutans strain Kl-R is not bound to the cell-wall structure, but is derived from a water-soluble form of the enzyme that becomes incorporated into the (dextran) cell-capsule during dextran synthesis. As synthesis of dextran proceeds, the initially soluble enzyme is converted into two dextran-bound enzyme fractions, one bound reversibly and the other bound irreversibly to the water-insoluble polysaccharide. The soluble dextransucrase is progressively changed to the irreversibly bound enzyme and is inactivated. In terms of the reaction... 

As noted previously, the family II PPases are not related to the family I enzymes in amino acid sequence. The crystal structure of the family II enzyme from S. mutans has recently been reported, and as expected there is no similarity in protein architecture between the two types of enzyme. The family II PPase consists of a two-domain structure, with a 189-residue N-terminal ajf3 domain connected to a 14-residue C-terminal ajf3 domain by a short linker. The active site lies at the domain interface and, most surprisingly, it is almost superimposable on the active site of the family I enzymes, with Mn + ions in the Ml and M2 sites, and Mg + in the M3 site. The major difference is that the family II structure lacks a metal binding site corresponding to M4. In addition, the active site contains two histidine residues, which are conserved in all family II PPase... 

Most of the microorganisms are bound and/or mechanically removed via discharge of mucus from the upper respiratory tract, or via the urine, saliva, and tears, or by entrapment and elimination in the intestinal contents before they have the opportunity to multiply. Some adhere to inert bodily structures. For example. Streptococcus mutans attaches to the enamel surface of the teeth (tartar, plaque) in order to elicit dental caries [13],... 

The water-soluble dextrans produced by a strain of Streptococcus mutans have been fractionated by gel chromatography into three types having different molecular sizes, chemical structures, and serological properties. One of the fractions and a water-insoluble dextran, also synthesized by the organism, appear to represent different physical states of an inherently identical D-glucan. 

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