Adhesion of Corynebacterium diphtheriae

The conditions for the direct hemagglutination test performed to determine the degree of adhesion of C. diphtheriae were defined. For this test sheep red blood cells, trypsin-treated ex tempore, were used. Only newly isolated cultures, subcultured for not more than 2-5 times and stored for not more than 2-7 days or freeze-dried, were employed. The culture to be tested was grown in nutrient agar with 10% of normal horse serum. The test was made in microtitrator round-bottom wells. The mixture of different dilutions of the culture was incubated for 2 hours at 37 degrees C, then left overnight at 4 degrees C. All 147 newly isolated or freeze-dried C. diphtheriae strains under test had different degrees of adhesion. Their adhesive activity was unrelated to their biovar. Toxigenic strains were significantly more active in hemagglutination (53.5 +/- 3.0%) than nontoxigenic ones (23.5 +/- 3.9%). The strains isolated from the nose, irrespective of their biological properties, were more active than those isolated from the pharynx.     

Adhesion in Corynebacterium diphtheriae

The study of 8 C. diphtheriae strains of different origin revealed that these strains were capable of inducing the agglutination of trypsinized sheep red blood cells (SRBC). Toxigenic strains gravis isolated from diphtheria patients were more active in their adhesion to SRBC than toxigenic strains gravis isolated from carriers. The latter were, in their turn, more active than nontoxigenic strains mitis. No fimbriae were detected on the cell surface by electron microscopy.     

Neuraminidase of Corynebacterium diphtheriae

Neuraminidase activity has been found in a variety of strains of Corynebacterium diphtheriae, both toxinogenic and nontoxinogenic. The enzyme has been shown to be intracellular, possibly associated with the cytoplasmic membrane. Toxinogenic strains of the diphtheria bacillus, grown under conditions unsuitable for maximal toxin production, produce neuraminidase, and the enzyme has been purified from cells of the Park Williams no. 8 strain grown under such conditions. Diphtherial toxin and diphtherial neuraminidase have similar molecular weights and remain associated during column chromatography; immunochemically, and in their electrophoretic behavior, they appear distinct.     

Three-dimensional models and structure analysis of corynemycolyltransferases in Corynebacterium glutamicum and Corynebacterium efficiens

The corynemycolyltransferase proteins were identified from Corynebacterium glutamicum and Corynebacterium efficiens genomes using computational tools available in the public domain. Three-dimensional models were constructed for corynemycolyltransferases based on the crystal structures of related mycolyltransferases in Mycobacterium tuberculosis using the comparative modeling methods. The corynemycolyltransferases share overall an alpha/beta-fold characteristic of the mycolyltransferases despite low sequence identity (<20%) shared by some of the corynemycolyltransferases. However, a significant difference is observed in the region between amino acid residues Trp82-Trp97 and Ala222-Asn223 corresponding to mycolyltransferases. The specificity pockets defined by interactions with the trehalose substrate observed in the crystal structure complex of Ag85B mycolyltransferase (PDB code: 1F0P) suggests that trehalose may not bind some corynemycolyltransferases. This is due to critical mutations in corynemycolyltransferase binding subsites that lead to loss of equivalent side-chain interactions with trehalose and unfavorable steric interactions, particularly, in the case of cmytC gene and the protein corresponding to the gene identifier CE0356 with the equivalent Ala222-Asn223 "long insertion loop". Further, the fibronectin binding region (Phe58-Val69), in mycolyltransferases associated with mediating host-pathogen interactions in M. tuberculosis comprises amino acid residue mutations in the corresponding region in the soil bacterium--Corynebacterium corynemycolyltransferases, that suggest a different epitope and therefore possible lack of binding to fibronectin. The corynemycolyltransferase cmytA responsible for the cell shape formation and for maintaining the cell surface integrity is associated with a C-terminal domain that we have recently shown to comprise tandem amino acid sequence repeats that is likely to be associated with a regular secondary structural motif.