The complete sequence of the 16,569-base pair human mitochondrial genome is presented. The genes for the 12S and 16S rRNAs, 22 tRNAs, cytochrome c oxidase subunits I, II and III, ATPase subunit 6, cytochrome b and eight other predicted protein coding genes have been located. The sequence shows extreme economy in that the genes have none or only a few noncoding bases between them, and in many cases the termination codons are not coded in the DNA but are created post-transcriptionally by polyadenylation of the mRNAs.

Sequence and organization of the human mitochondrial genome

https://www.jbc.org/content/252/3/1102.full.pdf

Peptide mapping by limited proteolysis in sodium dodecyl sulfate and analysis by gel electrophoresis.

The RNA moiety of ribonuclease P is the catalytic subunit of the enzyme

A 3'-end proximal segment of most of the putative mRNAs encoded in the heavy strand of HeLa cell mtDNA has been partially sequences and aligned with the DNA sequence. In all cases, the 3'-end nucleotide of the individual mRNA coding sequences has been found to be immediately contiguous to a tRNA gene or another mRNA coding sequence. These and previous results indicate that the heavy (H) strand sequences coding for the rRNA, poly(A)-containing RNA and tRNA species form a continuum extending over almost the entire length of this strand. We propose that the H strand is transcribed into a single polycistronic RNA molecule, which is processed later into mature species by precise endonucleolytic cleavages which occur, in most cases, immediately before and after a tRNA sequence.

tRNA punctuation model of RNA processing in human mitochondria

The DNA sequence of 168 promoter regions (-50 to +10) for Escherichia coli RNA polymerase were compiled. The complete listing was divided into two groups depending upon whether or not the promoter had been defined by genetic (promoter mutations) or biochemical (5' end determination) criteria. A consensus promoter sequence based on homologies among 112 well-defined promoters was determined that was in substantial agreement with previous compilations. In addition, we have tabulated 98 promoter mutations. Nearly all of the altered base pairs in the mutants conform to the following general rule: down-mutations decrease homology and up-mutations increase homology to the consensus sequence.

/pdf/compilation-and-analysis-of-escherichia-coli-promoter-dna-3laukojglx.pdf

Compilation and analysis of Escherichia coli promoter DNA sequences.

In certain mutants a single base change alters the meaning of a messenger codon in such a way that, instead of spelling out an amino-acid, it spells out chain termination. Mutants in a quite different gene, called a suppression gene, allow the chain-terminating triplet to be read as an amino-acid. Experiments have shown that this is caused by a mutated tRNA which carries a single base change in its anticodon. This allows it to read the chain-terminating codon as if it spelt tyrosine.

Amber suppression: a nucleotide change in the anticodon of a tyrosine transfer RNA.

http://www.jbc.org/content/247/16/5243.full.pdf

Purification and Properties of a Specific Escherichia coli Ribonuclease which Cleaves a Tyrosine Transfer Ribonucleic Acid Precursor

Image reconstruction to 22 A resolution of the histone octamer (H3)2(H4)2(H2A)2(H2B)2 shows it to have a 2-fold axis of symmetry, and the overall shape of the left-handed helical spool on which to wind about two turns of a flat superhelix of DNA in the nucleosome. From this structure and the results of various cross-linking studies, we have deduced the arrangement of the individual histones. We propose that the (H3)2(H4)2 tetramer forms a dislocated disk which defines the central turn of DNA, while the two H2A-H2B dimers lie one on each face, each associated with about one half a turn.

A low resolution structure for the histone core of the nucleosome

The transcribed precursor of an E. coli tyrosine tRNA contains nucleotide sequences not found in the mature tRNA. Evidence suggests that these regions, which can be trimmed in vitro by a nuclease activity in crude cell extracts, are involved in the control of cell tyrosine tRNA levels.

J.D. Smith

Papers

Amber suppression: a nucleotide change in the anticodon of a tyrosine transfer RNA.

Purification and Properties of a Specific Escherichia coli Ribonuclease which Cleaves a Tyrosine Transfer Ribonucleic Acid Precursor

A low resolution structure for the histone core of the nucleosome

Tyrosine tRNA precursor molecule polynucleotide sequence.

Duplicate genes for tyrosine transfer RNA in Escherichia coli