A mitochondrial cox3 gene in the alkane yeast, Yarrowia lipolytica, encodes a subunit-3 protein of cytochrome c oxidase, and contains a 1044 base-pair-long intron, as compared with the corresponding intronless gene in Saccharomyces cerevisiae. The intron belongs to a group I intron as determined by the cDNA sequence for the splicing sites as well as the predicted RNA secondary structure. Remarkably, this intron could code for a protein of 206 amino-acid residues which showed 63% similarity with an RNA maturase encoded by the second intron of the mitochondrial apocytochrome b gene in S. cerevisiae. Both introns occurred within the conserved exon sequence, 5'-TT(G/C)AGGTGC-3', suggesting the possible transposition of a common ancestral intron.

Amino Acid Sequence↗

PubMedDate not supplied

Organization and transcription of the mitochondrial ATP synthase genes in the yeast Yarrowia lipolytica.

Mitochondrial gene organization was studied in a dimorphic yeast, Yarrowia lipoltica. The gene order in a sequenced 6.6-kilobase region closely resembles that of the human mitochondrial genome in that ATP synthase subunit 8 and 6 genes are followed by genes for cytochrome c oxidase subunit 3 (which contains an intron), NADH-ubiquinone oxidoreductase subunit 4, and ATP synthase subunit 9. This region also contains tRNA genes decoding AUA, UGA, CUN and CCN codons, suggesting a unique mitochondrial translation. All the above genes are transcribed from the same DNA strand into multigenic RNAs, starting from a nonanucleotide sequence, 5'-ATATAAATA-3', similar to other yeast mitochondrial promoters.

Amino Acid Sequence↗

PubMedDate not supplied

A new way of enhancing the thermostability of proteases.

Thermostability of enzyme can be enhanced by single amino acid substitutions. Recent advances in genetic engineering have made it possible to create novel proteins in a predictable manner where structural information for the protein is available. This 'protein engineering' has already been used to enhance enzyme thermostability, but it is usually not clear which amino acid substitutions should be made. We consider that the following approach should be helpful in engineering proteins with enhanced thermostability: highly conserved residues should be left unchanged; the sequences of known mesophilic and thermophilic proteins should be used to suggest the kinds of changes likely to increase thermostability; and substitutions should be made that increase internal hydrophobicity and that stabilize helices for strong internal packing. We describe here the use of this approach to alter the thermostability of the thermostable neutral protease of Bacillus stearothermophilus, the sequence of which is known. Surprisingly we find that a single mutation that decreases thermostability can require two mutations that increase stability to compensate for it. The effects on stability are not additive, suggesting cooperativity.

Amino Acid Sequence↗

PubMedDate not supplied

Assessment of external dose to inhabitants evacuated from the 30-km zone soon after the Chernobyl accident.

According to reports by the former USSR government, IAEA and WHO, no case of acute radiation effects was recognized among inhabitants who were evacuated from the 30-km zone around the Chernobyl site soon after the accident on April 26, 1986. Along with the collapse of the USSR, however, several documents appeared that report the occurrence of acute radiation effects among inhabitants. In order to check the possibility of acute radiation effects among evacuees, we evaluated the external dose of evacuees until their evacuation based on the data about the radiation situation soon after the accident. Our estimates indicate that a substantial number of inhabitants in some villages could have received more than 0.5 Sv that is recognized by ICRP and UNSCEAR as a threshold dose for a clinically significant depression of the blood-forming function of bone marrow. Some of them could have received more than 1 Sv.

Disaster Planning↗