Comparative Immunology of Ribosomes and Disc Gel Electrophoresis of Ribosomal Proteins from Erwiniae, Pectobacteria, and Other Members of the Family Enterobacteriaceae

Abstract

Ribosomes from erwiniae, pectobacteria, and other Enterobacteriaceae were compared by two criteria: (i) disc gel electrophoresis of 50s subunit proteins, and (ii) Ouchterlony gel diffusion of intact ribosomes. There were no significant differences in the electrophoretic protein profiles of strains of Escherichia coli, Salmonella ty phim urium, Kle bsiella pneumo niae, or En terobacter agglorn erans (synonym: Erwinia herbicola). The only signficant profile differences occurred with the faster-migrating proteins of enterobacteria grouped according to plant or animal source. Several non-enterobacteria also had similar over-all profiles; however, specific differences were evident. Immuno-diffusion data were effective in establishing relatedness at the subspecies level. A single antigenic determinant was responsible for the specificity and was found t o differ in its sensitivity t o treatment with trypsin, ribonuclease, or heat.Results of investigations on the structure and function of ribosomes suggest the possibility of using ribosomes t o determine phylogenetic relationships of bacteria. All bacterial ribosomes studied have subunits with similar sedimentation coefficients, ribonucleic acid species, and amounts of protein (28,43). Ribosomal proteins are heterogenous (13, 2 1, 46), direct products of structural cistrons (36, 37, 44) and exhibit sequence and charge similarities between closely related species (2 1, 45). On the other hand, distantly related species have ribosomal proteins of similar molecular weights (41). Thus far, however, no single method of analysis has proven completely satisfactory in expressing comparative similarities or differences.Preliminary studies of subunit proteins by column chromatography (27) or total proteins by one-dimensional acrylamide gel electrophoresis ( 19) have shown that protein profiles from closely related bacteria exhibit more similarities than do profiles from distantly related bacteria. In fact, 60 strains of Escherichia coli have been classified into seven groups according t o their subunit protein composition (26). These methods have several disadvantages: accurate, unbiased comparisons are difficult; slight variability can occur between analyses; single bands often consist of more than one protein; and it has been difficult t o infer any relationship between proteins from two different ribosomes except when they are identical. The single-band problem has been solved by the two-dimensional gel electrophoresis technique (20); however, the other problems have not. The problems associated with analysis of total or subunit proteins suggested investigating not only the individual components but also ribosomal topography. Several studies have been initiated recently t o determine the topography and intimate structural arrangement of E. coli subunit ribosomes ( 5 , 6, 9, 14, 22). Based on trypsin sensitivity and gel electrophoresis, these studies have indicated that proteins are more exposed than ribonucleic acid (RNA) in the 3 0 s subunit, with the reverse being true for th...

Immunodiffusion Studies of Ribosomes in Classification of Mycobacteria and Related Taxa

“…It is doubtful whether phylogenetic relationships between bacteria ever can be established. However, comparative studies of ribosomes might possibly give a better picture of the phylogenetic status of bacteria than studies of many other preparations [15,19]. The background to this hypothesis is the aforementioned assumption that ribo somes probably have developed slowly in the course of evolution.…”

Enterobacterial common antigen.

“…The positions ofErwinia and Pectobacterium are not completely clear; they are included in the same genus ofEnterobacteriaceae in the 8th edition ofBergey's Manual (23). It is quite possible that the group is very heterogeneous and contains members close to Enterobacteriaceae (also ECA positive) and others that should not be so classified (six strains of "Erwinia chrysanthemi" examined were all ECA negative) (18,53,169).…”