Partial characterization of the Brucella species OMP2 gene products, and investigation on regulation of OMP2 gene expression /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1991.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | In B. abortus, a gene encoding a major cell envelope protein is duplicated within a short DNA segment. Even though a single gene product, Omp2b, has been detected in laboratory grown B. abortus cells, both genes, omp2a and omp2b, have open reading frames encoding highly homologous proteins of slightly different masses. In transformed E. coli strains, omp2b is expressed under the control of its own promoter, whereas expression of omp2a requires the insertion of an active promoter such as the omp2b promoter. Both gene products have been located in the outer membrane of E. coli, and there is strong evidence that B. abortus Omp2a and Omp2b are porins. The best evidence is the observed growth rate in the presence of various maltodextrins, and the kinetic uptake of maltose showing an increased hydrophilic permeability of the cells producing Omp2a, which is consistent with the presence of a large pore. Although no differences were observed in the hydrophilic permeability of cells expressing omp2b, the Omp2b protein exists as a polymer resistant to heat-denaturation at temperatures lower than 80°C in SDS buffer, which is characteristic of bacterial porins. The maintenance in B. abortus of two homologous porin genes suggest that an evolutionary adaptation has occurred at this locus. Investigations on the influence of various growth environments on omp2a and omp2b gene expression have revealed that osmolarity, a condition influencing the level of DNA supercoiling, modifies the level of expression of omp2b, whereas omp2a gene expression may be induced during infection of bovine macrophages. Finally, we have investigated the Omp2 proteins produced by the various Brucella species. Even though the omp2 gene locus is highly conserved among the species, the size and number of Omp2 protein bands detected varies for each species, and as a function of the growth conditions for B. canis, B. neotomae, and B. suis. Partial characterization of these proteins has revealed properties characteristic of porins, and their strong association with the peptidoglycan. In addition, this characterization has indicated that omp2a and omp2b genes may be reciprocally expressed in B. canis, B. neotomae, and B. suis. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Veterinary Microbiology." |
| Physical Description: | x, 112 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |