Complete nucleotide sequence of the chicken alpha A-crystallin gene and its 5' flanking region

The chicken alpha A-crystallin gene and 2.6 kb of its 5' flanking sequence have been isolated and characterized by electron microscopy and sequencing. The structural gene is 4.5 kb long and contains two introns, each approx. 1 kb in length. The first intron divides codons 63 and 64, and the second intron divides codons 104 and 105, as in rodents. There is little indication that the insert exon of rodents (an alternatively spliced sequence) is present in complete form in the chicken alpha A-crystallin gene; small stretches of similarity to this sequence were found throughout the gene. The 5' flanking sequence of the chicken alpha A-crystallin gene shows considerable sequence similarity with other mammalian alpha B-crystallin genes. In addition, one consensus sequence (GCAGCATGCCCTCCTAG) present in the 5' flanking region of the chicken alpha A-crystallin gene was found in the 5' flanking region of most reported crystallin genes.     

Sequence and heterogeneity in the 5S RNA gene cluster of Drosophila melanogaster.

The sequence of the entire 5S RNA gene of Drosophila melanogaster was determined by sequencing collectively 23 copies contained in a cloned fragment of Drosophila DNA and by sequencing individually four subcloned gene copies. A repetitive heptamer (GCTG CCT) present in variable numbers immediately following the coding sequence, is responsible for the length heterogeneity in the spacer region. Some of the gene copies contain a nucleotide change in the coding region which results in a new site for the restriction enzyme Mn1 I. The variant 5S RNA produced by these gene copies has not been detected in vivo. Two other single nucleotide variations were identified in the spacer region.     

Direct sequencing of tobacco chloroplast genome by the polymerase chain reaction

We have developed a polymerase chain reaction (PCR) method for sequencing of tobacco chloroplast genome. In a mixture containing chloroplast DNA, 5-end-labeled oligonucleotide primer, Taq DNA polymerase and reaction buffer, we were able to sequence a segment of chloroplast 16S rRNA gene. The results showed that the 750 bp of DNA sequenced were identical to the sequence reported, indicating that direct sequencing method that we have developed is useful for the sequencing of chloroplast genome. To analyze the chloroplast genome more rapidly in those in vitro grown plantlets, we also developed a simple method which is applicable for the amplifications and sequencing of chloroplast 16S rRNA fragment from either 0.15 g of tobacco leaf or stem tissue. The readable sequences obtained from the presented methods were consistent with the published sequence.     

Purification, cloning, and characterization of the 16S RNA m5C967 methyltransferase from Escherichia coli

The methyltransferase that forms m5C967 in Escherichia coli small subunit ribosomal RNA has been purified, cloned, and characterized. The gene was identified from the N-terminal sequence of the purified enzyme. The gene is a fusion of two open reading frames, fmu and fmv, previously believed to be distinct due to a DNA sequencing error. The gene, here named rsmB, encodes a 429-amino acid protein that has a number of homologues in prokaryotes, Archaea, and eukaryotes. C-Terminal sequencing of the overexpressed and affinity-purified protein by mass spectrometry methods verified the sequence expected for the gene product. The recombinant protein exhibited the same specificity as the previously described native enzyme; that is, it formed only m5C and only at position 967. C1407, which is also m5C in natural 16S RNA, was not methylated. In vitro, the enzyme only recognized free 16S RNA. 30S ribosomal subunits were not a substrate. There was no requirement for added magnesium, suggesting that extensive secondary or tertiary structure in the RNA substrate may not be a requirement for recognition.     

Molecular characterization of malQ, the structural gene for the Escherichia coli enzyme amylomaltase

The structural gene for the Escherichia coli enzyme amylomaltase, malQ, is the second gene in the malPQ operon. The nucleotide sequence of malQ shows that the gene encodes an Mr 78360 protein close to the experimentally determined Mr of purified amylomaltase (72000-74000). The malQ initiation codon was identified by sequence analysis of clustered deletions around the 5' end of the gene. One of these deletions removed the first 5 bases from the malQ coding sequence. Strains carrying a plasmid with this truncated malQ gene under lacZ promoter control and out-of-frame with the first four codons of lacZ were Mal-. The Mal+ phenotype could be restored by inserting small, random fragments of E. coli chromosomal DNA into the unique EcoRI site. Nucleotide sequencing showed that the inserts either joined the lacZ and malQ sequences in frame, or contained a new translation start signal and coding sequence in frame with malQ. These results indicate that amylomaltase could be useful as a reporter protein in gene fusion studies.     

Cloning and characterization of the C. elegans histidyl-tRNA synthetase gene.

In this paper, we report the cloning and sequencing of the C. elegans histidyl-tRNA synthetase gene. The complete genomic sequence, and most of the cDNA sequence, of this gene is now determined. The gene size including flanking and coding regions is 2230 nucleotides long. Three small introns (45-50 bp long) are found to interrupt the open reading frame. The open reading frame translates to 523 amino acids. This putative protein sequence shows extensive homology with the human and yeast histidyl-tRNA the histidyl-tRNA synthetase gene is a single copy gene. Hence, it is very likely that it encodes both the cytoplasmic and the mitochondrial histidyl-tRNA synthetases. It is likely to be trans-spliced since it contains a trans-splice site in its 5' untranslated region.     

Amino terminal sequence of the bacteriophage T5-coded gene A2 protein

The first twenty-eight amino acid residues from the amino terminal of the T5 phage-coded gene A2 protein were determined. Some evidence is presented which suggests the existence of two forms of the protein; one in the cytoplasm which may have a signal sequence and another form present in the outer membrane. The amino terminal A2 protein sequence shows some sequence homology to the amino terminal region of the T4 phage-coded gene 32 protein. Finally it is important to note that residues ten through twenty-one of the A2 protein are amino acids with low ambiguity codons which should facilitate in the DNA sequencing of the A2 gene.     

Nucleotide sequence of the dihydrofolate reductase gene of methotrexate-resistant Lactobacillus casei

The nucleotide sequence of the dihydrofolate reductase (DHFR) gene of a methotrexate-resistant strain of Lactobacillus casei, which is the source of DHFR for nuclear magnetic resonance (NMR) studies, has been determined. The derived amino acid sequence differs from that obtained by protein sequencing by the presence of aspartic acid instead of asparagine at position 8 and proline instead of leucine at position 90. The nucleotide sequences of 320-bp 5' and 335-bp 3' flanking regions of this gene have also been determined.     

High-Cot sequence analysis of the maize genome

Higher eukaryotic genomes, including those from plants, contain large amounts of repetitive DNA that complicate genome analysis. We have developed a technique based on DNA renaturation which normalizes repetitive DNA, and thereby allows a more efficient outcome for full genome shotgun sequencing. The data indicate that sequencing the unrenatured outcome of a Cot experiment, otherwise known as High-Cot DNA, enriches genic sequences by more than fourfold in maize, from 5% for a random library to more than 20% for a High-Cot library. Using this approach, we predict that gene discovery would be greater than 95% and that the number of sequencing runs required to sequence the full gene space in maize would be at least fourfold lower than that required for full-genome shotgun sequencing.     

Mutation detection by pyrosequencing: sequencing of exons 5-8 of the p53 tumor suppressor gene

The ability to sequence a large number of DNA samples rapidly and accurately for detection of all possible mutations is a critical goal for the future application of DNA sequencing in routine medical diagnostics. Pyrosequencing() is a non-electrophoretic real-time DNA sequencing method that uses the luciferase-luciferin light release as the detection signal for nucleotide incorporation into target DNA. For pyrosequencing of the human p53 gene, a nested multiplex PCR method for amplification of exons 5-8 was prepared. In order to investigate the use of pyrosequencing in mutation detection, DNA samples from skin-cancer patients were used. Two forms of nucleotide dispensation strategy were used, cyclic and programmed. Bi-directional pyrosequencing was performed and the overlapping sequence data produced were assembled to determine the sequence of the gene. Reliable sequencing data were obtained with both dispensation strategies, but some advantages were obtained using the programmed nucleotide dispensation approach, such as longer and faster reads, and fewer out-of-phase problems. The accuracy of pyrosequencing for detection of p53 mutations and allele distribution was demonstrated.