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D Sweetser

Publications and source records attributed to D Sweetser.

10 recordsLinked to original sources
PubMed1988

Stress proteins are immune targets in leprosy and tuberculosis.

To understand the immune response to infection by tuberculosis and leprosy bacilli and to develop improved vaccines, the nature of antigens that are involved in humoral and cell-mediated immunity was investigated. We have determined that five immunodominant protein antigens under study are homologues of stress proteins. This finding and observations with other pathogens suggest that infectious agents may respond to the host environment by producing stress proteins and that these proteins can be important immune targets. We postulate that abundant and highly conserved stress proteins may have "immunoprophylactic" potential for a broad spectrum of human pathogens.

Amino Acid Sequence↗
PubMed1987

Functional redundancy and structural polymorphism in the large subunit of RNA polymerase II.

The RNA polymerase II large subunit contains tandem copies of the sequence Pro Thr Ser Pro Ser Tyr Ser at its carboxyl terminus, the number of which varies from 26 in yeast to 52 in mice. Our results indicate that the heptapeptide repeat sequence is unique and essential to RNA polymerase II. We have determined that a portion of the heptapeptide repeat domain is essential for viability by constructing and analyzing unidirectional deletions of the carboxy-terminal coding sequence in yeast. Cells containing an RNA polymerase II large subunit with less than 10 complete heptapeptide repeats are inviable, those containing 10-12 complete repeats are conditionally viable, and those with 13 or more complete repeats are unconditionally viable. The inviable deletion mutants studied here have truncated RNA polymerase subunits that are stable, but functionally deficient. Finally, the number of repeat units is polymorphic in wild-type yeast strains. These results have implications for the function of this unusual sequence in transcription.

Amino Acid Sequence↗
PubMed1987

Prokaryotic and eukaryotic RNA polymerases have homologous core subunits.

Eukaryotic RNA polymerases are complex aggregates whose component subunits are functionally ill-defined. The gene that encodes the 140,000-dalton subunit of Saccharomyces cerevisiae RNA polymerase II was isolated and studied in detail to obtain clues to the protein's function. This gene, RPB2, exists in a single copy in the haploid genome. Disruption of the gene is lethal to the yeast cell. RPB2 encodes a protein of 138,750 daltons, which contains sequences implicated in binding purine nucleotides and zinc ions and exhibits striking sequence homology with the beta subunit of Escherichia coli RNA polymerase. These observations suggest that the yeast and the E. coli subunit have similar roles in RNA synthesis, as the beta subunit contains binding sites for nucleotide substrates and a portion of the catalytic site for RNA synthesis. The subunit homologies reported here, and those observed previously with the largest RNA polymerase subunit, indicate that components of the prokaryotic RNA polymerase "core" enzyme have counterparts in eukaryotic RNA polymerases.

Amino Acid Sequence↗
PubMed1986

Efficient mapping of protein antigenic determinants.

A recombinant DNA expression strategy has been used to deduce the amino acid sequences of six different antigenic determinants in a single protein of Mycobacterium leprae, the etiologic agent of leprosy. The gene encoding the M. leprae 65-kDa antigen was sequenced and a lambda gt11 gene sublibrary was constructed with fragments of the gene. Recombinant DNA clones producing specific antigenic determinants were isolated by screening with monoclonal antibodies, and the sequences of their insert DNAs were determined with a rapid primer-extension method. The amino acid sequence of each determinant was deduced from the minimum overlap of insert DNAs from multiple antibody-positive DNA clones. Amino acid sequences for six different epitopes were elucidated. A peptide containing sequences for one of these epitopes was synthesized and shown to bind the appropriate monoclonal antibody; this antigenic determinant is unique to M. leprae. The approach described here can be used to rapidly elucidate protein epitopes that are recognized by antibodies or T cells.

Amino Acid Sequence↗
PubMedDate not supplied

Genes for the major protein antigens of the leprosy parasite Mycobacterium leprae.

Leprosy, a chronic infectious disease afflicting between 10 and 15 million people, is caused by the obligate intracellular parasite Mycobacterium leprae. Although M. leprae was the first identified bacterial pathogen of man, basic biochemical, immunological, diagnostic and therapeutic investigations have been severely limited because it remains one of the few human pathogens that have not been cultured in vitro. An M. leprae recombinant DNA expression library was constructed to provide a source of genes encoding proteins relevant for such studies. Monoclonal antibodies directed against M. leprae specific antigens have been used to isolate the genes encoding the five most immunogenic protein antigens of the leprosy bacillus. We report here that M. leprae specific epitopes recognized by all of 13 monoclonal antibodies tested were produced by recombinant phage in Escherichia coli.

Antibodies, Monoclonal↗
PubMedDate not supplied

Identification of mycobacterial antigens recognized by T lymphocytes.

The development of vaccines capable of inducing protective immunity against mycobacterial infection depends in part on the identification of antigenic determinants that activate T cells with antimycobacterial effector function. Various approaches designed to analyze the recognition of mycobacterial antigens by T cells are reviewed. In addition to the established approach of using serologically defined antigens, alternative methods independent of antibody preselection, such as polyacrylamide gel electrophoresis-fractionated immunoblots of mycobacteria, can be used to probe the specificity of the T cell repertoire. Furthermore, the application of recombinant DNA expression combined with that of synthetic peptides whose sequences are predicted to constitute T cell determinants allow the localization of T cell epitopes within a protein. The use of these techniques in defining potentially "pathogenic and protective" T cell epitopes in mycobacteria is discussed.

Antigens, Bacterial↗