Biomedical subjects

M L Bittner

Publications and source records attributed to M L Bittner.

21 records · Page 2Linked to original sources

PubMed1988

Expression, isolation and properties of Fur (ferric uptake regulation) protein of Escherichia coli K 12.

The cloned fur (ferric uptake regulation) gene of Escherichia coli K12 was ligated to an expression vector which was inducible with nalidixic acid. The Fur protein was isolated in a single step by immobilized metal-ion-affinity chromatography over zinc iminodiacetate agarose. The amino acid composition of the isolated protein agreed with that predicted from the gene sequence and indicated post-transcriptional removal of the N-terminal methionine residue. All four cysteines were shown to be present as thiols. Proteolysis with trypsin and chymotrypsin yielded large fragments identifiable on polyacrylamide gel electrophoresis. Various divalent metal ions were found by a nitrocellulose filter binding assay to effect non-specific interaction of the Fur dimer with DNA with a dissociation constant of 7 x 10(-12) M. A much smaller value, 2.5 x 10(-17) M, was measured by gel mobility retardation assay for binding of Fur to a DNA fragment containing the operator sequences of the aerobactin promoter.

Amino Acid Sequence↗

PubMed1985

Purification of recA-based fusion proteins by immunoadsorbent chromatography. Characterization of a major antigenic determinant of Escherichia coli recA protein.

Monoclonal antibodies to Escherichia coli recA protein were prepared, characterized, and used as affinity reagents for the purification of recA and recA:somatostatin fusion proteins. The monoclonal antibodies recognize an antigenic determinant or determinants located between amino acids 260 and 330 of recA. Addition of a fragment of the recA gene coding for these amino acids to an unrelated gene (beta-galactosidase) allowed the resulting beta-galactosidase fusion protein to be recognized by the recA monoclonal antibodies.

Animals↗

PubMed1983

Expression of bacterial genes in plant cells.

Chimeric bacterial genes conferring resistance to aminoglycoside antibiotics have been inserted into the Agrobacterium tumefaciens tumor-inducing (Ti) plasmid and introduced into plant cells by in vitro transformation techniques. The chimeric genes contain the nopaline synthase 5' and 3' regulatory regions joined to the genes for neomycin phosphotransferase type I or type II. The chimeric genes were cloned into an intermediate vector, pMON120, and inserted into pTiB6S3 by recombination and then introduced into petunia and tobacco cells by cocultivating A. tumefaciens cells with protoplast-derived cells. Southern hybridization was used to confirm the presence of the chimeric genes in the transformed plant tissues. Expression of the chimeric genes was determined by the ability of the transformed cells to proliferate on medium containing normally inhibitory levels of kanamycin (50 micrograms/ml) or other aminoglycoside antibiotics. Plant cells transformed by wild-type pTiB6S3 or derivatives carrying the bacterial neomycin phosphotransferase genes with their own promoters failed to grow under these conditions. The significance of these results for plant genetic engineering is discussed.

Aminoglycosides↗