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Biomedical subjects

R Balakrishnan

Publications and source records attributed to R Balakrishnan.

At least 55 records · Page 3Linked to original sources
PubMed1989

Cloning and identification of bacteriophage T4 gene 2 product gp2 and action of gp2 on infecting DNA in vivo.

We sequenced bacteriophage T4 genes 2 and 3 and the putative C-terminal portion of gene 50. They were found to have appropriate open reading frames directed counterclockwise on the T4 map. Mutations in genes 2 and 64 were shown to be in the same open reading frame, which we now call gene 2. This gene codes for a protein of 27,068 daltons. The open reading frame corresponding to gene 3 codes for a protein of 20,634 daltons. Appropriate bands on polyacrylamide gels were identified at 30 and 20 kilodaltons, respectively. We found that the product of the cloned gene 2 can protect T4 DNA double-stranded ends from exonuclease V action.

Amino Acid Sequence↗
PubMed1988

Controllable alteration of cell genotype in bacterial cultures using an excision vector.

We have used recombinant DNA techniques to construct a derivative of phage lambda, called an excision vector, which retains only those functions necessary for conditional maintenance of lysogeny and integration/excision. The tyrA+ gene was cloned on this excision vector, integrated into the Escherichia coli chromosome, and stably maintained and expressed under permissive conditions. Upon shift to non-permissive conditions, the excision vector and its passenger gene were very efficiently excised from the chromosome and lost, leaving a culture of Tyr- bacteria. This illustrates a new class of conditional mutations in which the genotype changes in response to external stimuli.

Bacteriophage lambda↗
PubMed1982

Binding of the origin of replication of Escherichia coli to the outer membrane.

The replication origin of the Escherichia coli chromosome binds with high affinity to outer membrane preparations. This binding requires a 460 bp stretch of origin DNA between positions -40 and 420 of the oriC map. Specific binding can be detected by the use of a membrane filter retention assay in the presence of excess calf thymus DNA. This binding is enhanced by divalent cations and takes place specifically at a few (0.7-3.0) membrane sites per cell. The apparent affinity of origin DNA for membranes is enhanced by two peptides, (55 kilodaltons (kd) and 75 kd), which remain attached to the DNA through treatment with 5.5 M cesium chloride.

Bacterial Proteins↗
PubMed1980

Isolation of a replication origin complex from Escherichia coli.

A complex consisting of replicative origin DNA and several proteins was isolated from Escherichia coli. Cells of temperature-sensitive mutants were labeled at the origin and fractionated by sucrose gradient centrifugation. A complex highly purified in origin DNA sedimented as a unique band. This complex dissociated at high concentration, above 0.2 M KCl. Upon dialysis, the complex reformed, allowing further purification of its constituents. Three major protein bands were found, corresponding to proteins of the outer membrane. The complex did not sediment with membrane fractions, but adhered to the outer membrane in the presence of magnesium.

Bacterial Proteins↗