High impact information on PET54

• Disruption of the yeast nuclear PET54 gene blocks excision of mitochondrial intron aI5 beta from pre-mRNA for cytochrome c oxidase subunit I [1].
• The possibility that the PET54 protein binds to one or the other of these blocks of RNA sequence and the potential consequences of this interaction are discussed [1].
• Since, as we show here, PET54 is not an activator of PET494 gene expression, our results suggest that the products of both of these genes may act together to stimulate coxIII translation [2].
• Our data suggest that in wild-type cells, the specific activation of coxIII translation by PET494, PET54, and PET122 occurs by the action of these three gene products at a site or sites in a region of the 5' untranslated leader at least 172 nucleotides upstream of the initiation codon [3].
• While Ala at PET54 position 244 caused only a modest respiratory phenotype alone, it caused a severe respiratory defect when combined with a cold-sensitive mitochondrial mutation affecting the COX3 mRNA 5' leader [4].

Biological context of PET54

• Mutations in PET54 cause an absence of the coxIII protein despite the presence of normal levels of its mRNA. pet494 mutations are known to be suppressible by mitochondrial gene rearrangements that replace the normal 5'-untranslated leader of the oxi2 mRNA with the leaders of other mitochondrial mRNAs [2].
• PET54 is expressed from two mRNAs, both with unusual features: a major transcript with an extremely short 5'-untranslated leader, and a minor transcript with a relatively long 5'-leader carrying three short open reading frames [5].
• We have genetically mapped PET54 (to the right arm of chromosome VII, 4.8 cM centromere-distal to SUF15), and have biochemically characterized the gene and its product [5].
• We determined the nucleotide sequence of a 1.6-kb DNA fragment carrying PET54 and identified the PET54 reading frame by determining the sequence of an ochre mutant allele as well as frameshift and frameshift-revertant alleles of the gene [5].
• However, the 5'-UTL insertion mutation enhanced the respiratory defective phenotype of missense mutations in pet54, one of the COX3-specific translational-activator genes [6].

Anatomical context of PET54

• Approximately half of the PET54 protein present in mitochondria from wild-type cells pelleted with membranes, while half was released from disrupted mitochondria in soluble form [7].
• These data suggest the possibility that synthesis of the highly hydrophobic subunit III of cytochrome c oxidase is activated by PET54, PET122, and PET494 at the inner mitochondrial membrane [7].
• Antiserum raised against a trpE-PET54 fusion protein was used to probe subcellular fractions [5].
• The majority of each class of PET54 mRNA was associated with polysomes in vivo [8].

Other interactions of PET54

• A quantitative RT-PCR assay was set up to compare levels of spliced COX1 mRNA present in three strains: a wild-type rho + strain; the rho-strain 7-49b-11, which retains the entire COX1 transcription unit; and a strain bearing a null mutation in the nuclear PET54 gene [9].

Analytical, diagnostic and therapeutic context of PET54

• The membrane-bound PET54 floated with the inner membrane during buoyant density gradient centrifugation, but was efficiently solubilized by extraction with alkaline carbonate [7].

References