Biomedical subjects
Publications and source records attributed to K Saigo.
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The major flavin reductase from Vibrio fischeri, FRase I, has been crystallized in the presence of FMN by the vapor diffusion method using polyethylene glycol 4000 as a precipitant. The crystals belonged to the monoclinic space group C2 with unit cell dimensions, a = 101.6 A, b = 63.2 A, c = 74.4 A, and beta = 100.0 degrees. The crystals are expected to contain two FRase I molecules per asymmetric unit. The crystals diffracted X-rays to at least 2.2 A resolution and are appropriate for structural analysis at high resolution.
As in the case of retrovirus proviruses, most of the Drosophila copia-like transposable elements so far examined are bounded by 5'TG...CA3' and inserted into the chromosome without obvious site-specificity. In the other copia-like elements, 297, HMS Beagle and 17.6 (refs 5-7), terminal dinucleotides (5'TG...CA3') are completely absent and, instead, 5'(A)GT is present at least at one of the termini. One important feature of these three elements may be frequent insertion into 'TATA' boxes, since the three of four insertion sites so far examined were TATA boxes, two for H3 histone genes and one for a cuticle gene. Because of the importance of this type of insertion, we extensively analysed site-specificity using 17.6 as a model. Our results, described here, suggest that insertion of 17.6 takes place in a site-specific fashion, using a target 5'ATAT corresponding to the major portion of the consensus TATA box, TATAATAAT.
The largest group of transposable elements in Drosophila melanogaster, copia-like elements, share some important structural features with and are intimately related in evolution to vertebrate retroviruses. To further clarify the relationship between retroviruses and copia-like transposable elements, we set out to determine the complete nucleotide sequence of the genome of 17.6, which has long terminal repeats homologous in nucleotide sequence to those of avian leukaemia-sarcoma virus. We report here that 17.6 contains three long open reading frames comparable with gag, pol and env genes in retrovirus. At the level of amino acid sequence, the longest open reading frame of 17.6 includes a coding sequence similar to that for reverse transcriptase, suggesting a role for this enzyme in the life cycle of some Drosophila copia-like elements, analogous to the situation in retrovirus.
We have shown previously that Drosophila cells contain virus-like particles (VLPs) containing 5-kilobase (kb) RNA that hybridizes to a transposable element, termed copia. We have suggested that VLPs and copia are derivatives of viral particles and proviral forms, respectively, of 'copia' retrovirus, a putative Drosophila retrovirus. To further clarify the relationship between copia and copia-related RNA in VLPs (VLP H-RNA), we determined and compared their nucleotide sequences. VLP H-RNA was found to be an unspliced, genome-sized transcript of copia, and, like retroviral genome RNA, VLP H-RNA is terminally redundant with termini localized in the long terminal repeats (LTRs) of copia. VLP H-RNA contains two long open reading frames (ORFs), one of which includes the coding sequence for a predominant VLP protein of relative molecular mass (Mr) 31,000 (31K). Here we show that, in contrast to 17.6 ORF2, ORFs of copia have no extensive amino-acid sequence homology to the RT region of the reverse transcriptase of retrovirus in vertebrates. Because of a one-base insertion/deletion, the two ORFs in VLP H-RNA are fused and become a single, longer ORF in a genomic copia.
A 69-year-old man with acute myelogenous leukaemia developed a transfusion-related acute lung injury (TRALI). He had anti-IgA2m(1) antibody rather than other antibodies that have previously been reported to be related to TRALI. This case suggests that the pre-existing condition of patients may be important in the development of TRALI.