Biomedical subjects

J L Eliason

Publications and source records attributed to J L Eliason.

4 recordsLinked to original sources

PubMed1987

Characterization of the binding sites of c1 repressor of bacteriophage P1. Evidence for multiple asymmetric sites.

The repressor of bacteriophage P1, encoded by the c1 gene, is responsible for maintaining a P1 prophage in the lysogenic state. In this paper we present: (1) the sequence of the rightmost 943 base-pairs of the P1 genetic map that includes the 5'-terminal 224 base-pairs of the c1 gene plus its upstream region; (2) the construction of a plasmid that directs the production of approximately 5% of the cell's protein as P1 repressor; (3) a deletion analysis that establishes the startpoint of P1 repressor translation; (4) filter binding experiments that demonstrate that P1 repressor binds to several regions upstream from the c1 gene; (5) DNase I footprint experiments that directly identify two of the P1 repressor binding sites. Sequences very similar to the identified binding sites occur in at least 11 sites in P1, in most cases near functions known, or likely, to be controlled by repressor. From these sites we have derived the consensus binding site sequence ATTGCTCTAATAAATTT. We suggest that, unlike other phage operators, the P1 repressor binding sites lack rotational symmetry.

Base Sequence↗

PubMed1985

NH2-terminal arm of phage lambda repressor contributes energy and specificity to repressor binding and determines the effects of operator mutations.

Several lines of evidence indicate that the phage lambda repressor recognizes its operator by using, in part, an alpha helix (the "recognition helix"), which it inserts into the major groove of DNA. In addition to its recognition helix, lambda repressor has an "arm," consisting of the first six amino acids, that wraps around the DNA helix. We constructed plasmids that, in Escherichia coli, direct the expression of derivatives of lambda repressor that lack the NH2-terminal one, three, six, or seven amino acids. We studied these modified proteins in vivo and in vitro, and from our results we argue that the arm: contributes a large portion of the binding energy; helps to determine sequence specificity of binding and, in particular, the relative affinities for two wild-type binding sites; determines entirely repressor's response to one operator mutation (a "back-side" mutation); magnifies repressor's response to other operator mutations ("front-side" mutations); and increases the sensitivity of repressor binding to salt concentration and temperature.

Amino Acid Sequence↗

PubMed1984

Dynamic filtering by two-dimensional 1H NMR with application to phage lambda repressor.

Flexible regions of proteins play an important role in catalysis, ligand binding, and macromolecular interactions. Because of its enhanced sensitivity to motional narrowing, two-dimensional coupling constant J-correlated 1H NMR may be used to observe these regions selectively. Dynamic filtering is an intrinsic feature of this experiment because cross-peak amplitude decays rapidly as linewidths approach the coupling constant. We demonstrate here the flexibility of the NH2-terminal arm of phage lambda repressor, which is thought to wrap around the double helix in the repressor-operator complex. The assignment of arm resonances is made possible by the construction of mutant repressor genes containing successive NH2-terminal deletions.

Bacteriophage lambda↗

PubMedDate not supplied

Durability of percutaneous angioplasty and stent implantation for the treatment of abdominal aortic coarctation: a case report.

Abdominal aortic coarctation (AAC) is an uncommon vascular lesion with serious sequelae related to uncontrolled hypertension. Balloon-expandable stents have recently been utilized in the treatment of AAC as an alternative to surgical intervention. A 17-year-old female presented with hypertension uncontrolled by beta blockade. She underwent angiography, which revealed an isolated supraceliac aortic coarctation without visceral or renal artery involvement. Balloon angioplasty with stent placement was performed. At 2-year follow-up, a restenosis was identified and was treated with repeat balloon-expandable stent placement. Implantation of balloon-expandable stents is a safe and technically feasible treatment modality for abdominal aortic coarctation not involving the renal and mesenteric arteries. However, it is currently unknown whether the long-term durability of this approach may limit its effectiveness when compared to traditional surgical interventions.

Adolescent↗