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Cloning and molecular genetic analysis of Drosophila melanogaster interband DNA.

Interband DNA of Drosophila melanogaster polytene chromosomes was studied using a novel approach based on the electron microscopic (EM) analysis of chromosome regions carrying DNA fragments of known molecular genetic composition, inserted by P element-mediated transformation. Insertion of such fragments predominantly into interbands makes it possible to clone interband DNA by constructing genomic libraries from transformed strains and probing them with the insert DNA. The transformed strain P[H-sp70:Adh](61C) has insertion in the 61C7-8 interband on the left arm of chromosome 3. This DNA consists of part of the hsp70 gene promoter fused to the coding region of the Adh gene, and is flanked on either side by P element sequences. We constructed a genomic library from DNA of this strain and isolated a clone containing the insert and the interband DNA. Subsequently the genomic library of wild-type strain was probed with a subclone composed of interband DNA only. We have thus isolated a clone containing the entire native interband. 1289 bp of interband DNA was sequenced and found to be AT-rich (53.4%) with numerous regions of overlapping direct and inverted repeats, regulatory sites, and two overlapping open reading frames (ORFs).

Animals↗

Expression of the gene encoded by a family of macronuclear chromosomes generated by alternative DNA processing in Oxytricha fallax.

Hypotrichous ciliated protozoa, such as Oxytricha fallax, produce tiny chromosomes during generation of the transcriptionally active macronucleus. The 81-MAC family of macronuclear chromosomes is produced by alternative DNA processing, such that the chromosomes share a common region of 1.6 kbp. Transcription of a 1.3 kb mRNA from the common region has been analyzed. Transcription starts very near the telomere (34 bp), in a 23 bp region of pure A + T DNA. Polyadenylation sites are very near the other telomere (26 bp), also in a region of nearly pure A + T DNA. Three introns are clustered in the first third of the gene. Intron removal can follow polyadenylation, and the order of removal is not fixed. All three known sequence versions of the 81-MAC chromosomes are represented in the mRNA pool, with no evidence of any further versions. The A + T sequences surrounding the transcription starts and polyadenylation sites are conserved among versions. Introns have conserved 5' and 3' ends and a putative branch-point sequence (YYRAT), but otherwise are highly diverged and are AT-rich. A single long open reading frame, interrupted by the three introns, encodes a homolog of known mitochondrial solute carriers, and contains the codon TAA, which does not encode 'stop,' but a conserved glutamine; TAG appears also to encode glutamine. The results significantly enlarge the small data set of transcription start and polyadenylation sites, of intron features, and of translation signals for hypotrichs.

Animals↗

The complete nucleotide sequence of apple mosaic virus (ApMV) RNA 1 and RNA 2: ApMV is more closely related to alfalfa mosaic virus than to other ilarviruses.

The complete nucleotide sequences of apple mosaic virus RNA 1 and 2 have been characterized. Apple mosaic virus RNA 1 is 3476 nucleotides in length and encodes a single large open reading frame (ORF), whereas apple mosaic virus RNA 2 is 2979 nucleotides in length and also encodes a single ORF. The amino acid sequences encoded by RNA 1 and 2 show similarity to all of the other ilarviruses for which sequence data are available, but both are more closely related to alfalfa mosaic virus (AMV) than to other ilarviruses. Points of similarity include the absence of ORF 2b, present on the RNA 2 of all previously characterized ilarviruses. The close relationship to AMV also occurs in the movement protein, encoded by RNA 3, but not with the coat protein. These data suggest that the present taxonomy should be revised, and that AMV should be considered an aphid-transmissible ilarvirus.

5' Untranslated Regions↗

The nucleotide sequence of the bacteriophage T5 ltf gene.

The nucleotide sequence of the bacteriophage T5 Bg/II-BamHI fragment (4,835 bp in length) known to carry a gene encoding the LTF protein which forms the phage L-shaped tail fibers was determined. It was shown to contain an open reading frame for 1,396 amino acid residues that corresponds to a protein of 147.8 kDa. The coding region of ltf gene is preceded by a typical Shine-Dalgarno sequence. Downstream from the ltf gene there is a strong transcription terminator. Data bank analysis of the LTF protein sequence reveals 55.1% identity to the hypothetical protein ORF 401 of bacteriophage lambda in a segment of 118 amino acids overlap.

Amino Acid Sequence↗

Identification, cloning, and nucleotide sequencing of the ornithine decarboxylase antizyme gene of Escherichia coli.

The ornithine decarboxylase antizyme gene of Escherichia coli was identified by immunological screening of an E. coli genomic library. A 6.4-kilobase fragment containing the antizyme gene was subcloned and sequenced. The open reading frame encoding the antizyme was identified on the basis of its ability to direct the synthesis of immunoreactive antizyme. Antizyme shares significant homology with bacterial transcriptional activators of the two-component regulatory system family; these systems consist of a "sensor" kinase and a transcriptional regulator. The open reading frame next to antizyme is homologous to sensor kinases. Antizyme overproduction inhibits the activities of both ornithine and arginine decarboxylases without affecting their protein levels. Extracts from E. coli bearing an antizyme gene-containing plasmid exhibit increased antizyme activity. These data strongly suggest that (i) the cloned gene encodes the ornithine decarboxylase antizyme and (ii) antizyme is a bifunctional protein serving as both an inhibitor of polyamine biosynthesis as well as a transcriptional regulator of an as yet unknown set of genes.

Amino Acid Sequence↗

The complete sequence of a 6146 bp fragment of Saccharomyces cerevisiae chromosome III contains two new open reading frames.

As part of the EEC project to sequence the entire chromosome III of Saccharomyces cerevisiae we have sequenced a total of 11,040 bp from near the right end of the chromosome. A new protein kinase gene was found at one extremity of the sequenced region (Wilson et al., 1992), while the previously sequenced actin binding protein gene, ABP1, (Drubin et al., 1990) was found at the other extremity. We present here the sequence of the region between these two genes which has the potential to code for two new open reading frames (ORFs).

Amino Acid Sequence↗

The TSM1 gene of Saccharomyces cerevisiae overlaps the MAT locus.

We have cloned the region from MAT to THR4 on chromosome III of Saccharomyces cerevisiae. Although the region is only 15 kb, the two loci are genetically separated by 22 cM. This is in sharp contrast to the very low level of recombination (2 cM in 22 kb) that is observed in the adjacent CRY1-MAT interval, and suggests that there may be a "hot spot" for recombination in the MAT-THR4 region. The DNA sequence of the first 4.4 kb distal to MAT reveals an open reading frame that we have identified as the essential gene, TSM1. Surprisingly, the TSM1 open reading frame of 1,410 amino acids extends into the MAT locus, such that the 3'-end of the MAT alpha 1 transcript ends 15 bp from the 3'-end of the TSM1 open reading frame.

Alleles↗

Reconstitution of transcription from the human U6 small nuclear RNA promoter with eight recombinant polypeptides and a partially purified RNA polymerase III complex.

The human U6 small nuclear (sn) RNA core promoter consists of a proximal sequence element, which recruits the multisubunit factor SNAP(c), and a TATA box, which recruits the TATA box-binding protein, TBP. In addition to SNAP(c) and TBP, transcription from the human U6 promoter requires two well defined factors. The first is hB", a human homologue of the B" subunit of yeast TFIIIB generally required for transcription of RNA polymerase III genes, and the second is hBRFU, one of two human homologues of the yeast TFIIIB subunit BRF specifically required for transcription of U6-type RNA polymerase III promoters. Here, we have partially purified and characterized a RNA polymerase III complex that can direct transcription from the human U6 promoter when combined with recombinant SNAP(c), recombinant TBP, recombinant hB", and recombinant hBRFU. These results open the way to reconstitution of U6 transcription from entirely defined components.

Amino Acid Sequence↗

Cloning and characterization of a complete open reading frame of the hepatitis C virus genome in only two cDNA fragments.

The synthesis of long cDNA molecules encoding the complete genome of RNA viruses has recently been demonstrated; this major improvement has numerous practical applications such as construction of infectious cDNA clones or study of sequence variability at the level of a single RNA molecule. Using hepatitis C virus (HCV) as a model, we established an RT-PCR technique for amplification of cDNA fragments with a length of about 5 kb. The RT reaction was carried out with a Moloney murine leukaemia virus reverse transcriptase lacking detectable RNase H activity. For PCR reactions an enzyme mix containing Taq and Pwo DNA polymerases was used. Hot start and addition of 5% DMSO were also important to efficiently achieve long PCR products. About 10(6) HCV genome equivalents/ml in serum were needed in order to amplify the HCV genome in only two cDNA fragments covering about 98% of the complete genome. Analysis of the HCV quasi-species is also possible by this method as shown by sequencing of the hypervariable region 1 (HVR1) after cloning of cDNAs. The integrity of the long cDNA clones was proven by (1) restriction analyses, (2) partial sequencing and (3) expression of respective gene products. In vitro transcribed cDNAs were translated in rabbit reticulocyte lysate. Structural and nonstructural HCV proteins were identified by immunoprecipitation using patient serum. These results suggest that the two cDNA clones encode a complete and functional open reading frame of HCV.

Amino Acid Sequence↗

Antisense RNA mediates transcriptional processing in an archaebacterium, indicating a novel kind of RNase activity.

Strains of the extremely halophilic archaebacterium Halobacterium salinarium that are lysogenic for the phage phi H produce an antisense RNA transcript complementary to the first 151 nucleotides (nt) of the early lytic phage transcript T1. This is the first case of antisense control of gene expression in an archaebacterium. We show through transformation of H. salinarium that the antisense RNA functions in trans, rendering the early lytic phage transcript T1 susceptible to specific cleavage by an unidentified RNase of unique endonucleolytic activity. The single-stranded ends of RNA are cut off at the ends of the 151 nt RNA duplex, removing the ribosomal binding sites from the first open reading frame of transcript T1 but without concomitant digestion of the products.

Amino Acid Sequence↗

Plasmids from two morphologically distinct cyanobacterial strains share a novel replication origin.

A 2.9-kbp replication origin from a plasmid endogenous to the filamentous cyanobacterium Fremyella diplosiphon UTEX 481 was genetically characterized and sequenced. Deletion analysis of the 2.9-kbp DNA fragment delimited the minimum region necessary for replication in F. diplosiphon Fd33 to approximately 2.5 kbp. DNA sequence analysis revealed that the F. diplosiphon plasmid replication origin is structurally very similar to and shares significant identity with the 1.75-kbp replication origin reported for plasmid pDU1, isolated from the morphologically distinct cyanobacterium Nostoc sp. strain PCC 7524. Each cyanobacterial plasmid replication origin includes a large open reading frame that predicts a conserved protein of unknown function; the predicted proteins of the replication origins are of similar sizes and 30% identical in amino acid sequence. Each cyanobacterial plasmid replication origin also possesses a region of dyad symmetry approximately 300 bp upstream of the conserved open reading frame.

Amino Acid Sequence↗

Analysis of the DNA sequence of a 34,038 bp region on the left arm of yeast chromosome XV.

We report the DNA sequence of a 34,038 bp segment of Saccharomyces cerevisiae chromosome XV. Subsequent analysis revealed 20 open reading frames (ORFs) longer than 300 bp and two tRNA genes. Five ORFs correspond to genes previously identified in S. cerevisiae, including RPLA2, PRE6, MSE1, IFM1 and SCM2 (TAT2, TAP2, LTG3). Two putative proteins share considerable homology with other proteins in the current data libraries. ORF O2145 shows 41.2% identity with the glycophospholipid-anchored surface glycoprotein Gas1p of S. cerevisiae and ORF O2197 has 53.2% identity to chromosome segregation protein Dis3p of Schizosaccharomyces pombe.

Amino Acid Transport Systems↗

Sequence of a 17.1 kb DNA fragment from chromosome X of Saccharomyces cerevisiae includes the mitochondrial ribosomal protein L8.

We have sequenced a continuous segment of 17,137 bp on chromosome X. Sequence analysis of this stretch revealed 14 open reading frames (ORFs) at least 100 amino acids long. One gene, encoding the mitochondrial 60S ribosomal protein L8, had already been sequenced. Four ORF products show weak homologies with known protein sequences. The nine remaining ORF products have no homologies with sequences in data banks.

Carboxylesterase↗

Sequence analysis of a 13.4 kbp fragment from the left arm of chromosome XV reveals a malate dehydrogenase gene, a putative Ser/Thr protein kinase, the ribosomal L25 gene and four new open reading frames.

A 13421 bp fragment located near the left telomere of chromosome XV (cosmid pEOA461) has been sequenced. Seven non-overlapping open reading frames (ORFs) encoding polypeptides longer than 100 residues have been found (AOB859, AOC184, AOE375, AOX142i, AOE423, AOA476 and AOE433). An additional ORF (AOE131) is found within AOA476. Three of them (AOC184, AOA476 and AOE433) show no remarkable identity with proteins deposited in the data banks. ORF AOB859 is quite similar to a hypothetical yeast protein of similar size located in chromosome VI, particularly within the C-terminal half. AOE375 encodes a new member of the glycogen synthase kinase-3 subfamily of Ser/Thr protein kinases. AOX142i is the gene encoding the previously described ribosomal protein L25. AOE423 codes for a protein virtually identical to the MDH2 malate dehydrogenase isozyme. However, our DNA sequence shows a single one-base insertion upstream of the reported initiating codon. This would produce a larger ORF by extending 46 residues the N-terminus of the protein. The existence of this insertion has been confirmed in three different yeast strains, including FY1679.

Amino Acid Sequence↗

Sequence of the CDC10 region at chromosome III of Saccharomyces cerevisiae.

A 4.74 kb DNA fragment from the right arm of chromosome III of Saccharomyces cerevisiae, adjacent to the centromere region was sequenced. Four open reading frames with an ATG initiation codon and larger than 200 bp were found in this fragment. The largest open reading frame of 966 bp was identified as the CDC10 gene.

Base Sequence↗