PubMed Health⌕ Search

Biomedical subjects

A S Gopalakrishnan

Publications and source records attributed to A S Gopalakrishnan.

6 recordsLinked to original sources
PubMed1986

Structure and expression of the gene locus encoding the phosphatidylglycerophosphate synthase of Escherichia coli.

This paper presents definitive results which establishes a direct gene-protein product relationship between the pgsA gene and the phosphatidylglycerophosphate synthase of Escherichia coli. The predicted protein sequence derived from the determined DNA sequence of pgsA is in close agreement with the amino acid composition and partially determined amino acid sequence of the purified enzyme. The purified synthase has the same apparent molecular mass as the gene product made by a plasmid-directed transcription-translation system. The plasmid-borne copy of the pgsA gene is also capable of expressing enzymatically active synthase in vitro. The DNA sequence analysis has established the exact linear relationship between the uvrC, pgsA, and glyW loci and revealed that these three genes are transcribed in the same direction. The terminal coding regions of these three genes also share common sequences with transcriptional regulatory elements for the adjacent genes.

Amino Acid Sequence↗
PubMed1986

Sequence specific antibodies to a deoxyribodinucleotide.

Antibodies were elicited in rabbits to the dinucleotide, dpTpA, conjugated to a carrier protein. Among a few deoxyribomono- and oligonucleotides tested for binding to the antibodies by nitrocellulose tilter binding assay, only dpTpA and dpTpA containing oligonucleotides showed binding. The inhibition of the binding of 3H-dpTpA to the antibodies by various nonradioactive mono- and oligonucleotides showed that the antibodies were sequence specific and recognized the whole molecule of dpTpA. dpTpA specific antibodies were purified by a two step affinity chromatography. By competition studies, it was found that the purified antibodies bound denatured DNA at dpTpA sequences. The antibodies did not bind RNA.

Antibodies↗
PubMed1982

Molecular mapping of glyW, a duplicate gene for tRNA3Gly of Escherichia coli.

By the use of [5'-32P]tRNA3Gly from Escherichia coli as a hybridization probe, glyW was located on cloned fragments of the uvrC pgsA region of the bacterial chromosome. After determination of the sites of action of several restriction enzymes, glyW was found to be within approximately 300 base pairs of pgsA. The order of genes in this region is uvrC, pgsA, glyW, flaI. Comparison of the order of determined restriction sites with the sites predicted from the nucleotide sequence of tRNA3Gly indicates that the direction of transcription of glyW is counterclockwise on the circular E. coli map.

Base Sequence↗
PubMed1981

Lack of a specific ribose methylation at guanosine 17 in Morris hepatoma 5123D tRNASer1IGA.

Tumor transfer RNA's (tRNA's) frequently exhibit alterations in column chromatographic profiles and in base compositions when compared to their normal counterparts. Because such alterations may be involved in the dedifferentiated state of cancer cells, it is of interest to determine their structural basis and functional significance. The recent development of highly sensitive postlabeling methods has now made possible sequence analysis of tRNA's from neoplastic tissues available only in limited amounts. We have determined the nucleotide sequence of Morris hepatoma serine tRNA (anticodon IGA) and compared it with its normal counterpart in rat liver. The tumor serine tRNA was found to lack the ribose methylation of guanosine in position 17 of the dihydrouridine loop present in the liver RNA. This result explains the column chromatographic shifts of Morris hepatoma 5123D seryl-tRNA isoacceptors, suggesting that all seryl-tRNA isoacceptors may lack this modification.

Animals↗