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A A Janulaitis

Publications and source records attributed to A A Janulaitis.

9 recordsLinked to original sources
PubMed1991

The Saccharomyces cerevisiae ADE1 gene: structure, overexpression and possible regulation by general amino acid control.

The ADE1 gene of the yeast Saccharomyces cerevisiae has been cloned by complementation of the ade1 mutation. The nucleotide sequence has been determined for the 918-bp coding region, 240-bp 5'-noncoding region and 292-bp 3'-noncoding region. The sequenced region includes a single large open reading frame coding for a protein of 306 amino acid (aa) residues. The promoter of the ADE1 gene contains a copy of the 5'-TGACTC hexanucleotide, a feature characteristic of promoters under general aa control. Subsequent search of other published purine biosynthesis gene sequences revealed that all of them also contain general aa control signals in their promoter regions. An expression plasmid containing the ADE1 coding region under control of the PHO5 promoter produced N-succinyl-5-aminoimidazole-4-carboxamide ribotide (SAICAR) synthetase in yeast cells at a level of 40% of total cellular protein. One-step purification resulted in an almost homogeneous preparation of SAICAR synthetase.

Amino Acid Sequence↗
PubMed1989

Phasmids as effective and simple tools for construction and analysis of gene libraries.

Phasmid lambda pMYF131, a hybrid of phage lambda vectors and plasmid pUC19, was constructed. The phasmid and its derivatives were shown to be efficient vectors for construction and analysis of gene libraries in Escherichia coli cells. The lambda pMYF131 DNA molecule contains all the genes and regions essential for phage lytic development. The plasmid cannot be packaged either in the monomeric or the oligomeric form due to its specific length. Elongation of the DNA molecule by ligation with fragments of foreign DNA can make it packageable and this is easily detected by plaque formation. Hence, the procedures used to construct genomic libraries can be simplified by selection of only recombinant DNA molecules just at the time and on the basis of their packaging in vitro. The output of recombinant clones per vector molecule was several times higher for vector lambda pMYF131, compared to phage vector lambda L47.1AB, and attained 3 x 10(6) clones per micrograms DNA. Vector and recombinant phasmids can be obtained in large quantities in plasmid form. lambda pMYF131 contains nine unique restriction sites which allow the cloning of DNA fragments with blunt ends and of fragments with various types of cohesive ends, obtained by digestion with 14 prototype restriction enzymes. The maximal size of the cloned DNA fragments is approx. 20 kb for lambda pMYF131. Phasmid vectors were used to construct libraries of bovine, pig and quail genomes, and genomic libraries of 17 species of bacteria. Application of suitable methods allowed the identification 13 individual genes within these libraries.

Bacteriophage lambda↗
PubMed1988

Precise excision of bacterial transposon Tn5 in yeast.

We have demonstrated that precise excision of bacterial transposon Tn5 can occur in the yeast, Saccharomyces cerevisiae. Tn5 insertions in the yeast gene LYS2 were generated by transposon mutagenesis made in Escherichia coli by means of a lambda::Tn5 vector. Nine insertions of Tn5 into the structural part of the yeast LYS2 gene situated in a shuttle episomal plasmid were selected. All the plasmids with a Tn5 insertion were used to transform yeast strains carrying a deletion of the entire LYS2 gene or a deletion of the part of LYS2 overlapping the point of insertion. All insertions inactivated the LYS2 gene and were able to revert with low (about 10(-8) frequencies to lysine prototrophy. Restriction analysis of revertant plasmids revealed them to be indistinguishable from the original plasmid without Tn5 insertion. DNA sequencing of the regions containing the points of insertions, made for two revertants, proved that Tn5 excision was completely precise.

DNA Transposable Elements↗
PubMed1985

Characterization of restriction-modification enzymes Cfr13 I from Citrobacter freundii RFL13.

This communicatiopn describes some properties of RCfr13 I and MCfr13 I, isolated from Citrobacter freundii RFL13. RCFfr13 I restriction enzyme recognizes the 5'-G GNCC sequence and cleaves, as indicated by the arrow. MCfr13 I methylase modifies the internal cytosine producing m5C (5'-GGNm5CC). RCfr13 I is sensitive not only to this type of substrate modification but also to hemimethylation in overlapping sites by MCfr10 I (internal cytosine of RCfr13 I recognition is methylated) and MHpa II (external cytosine is methylated). From these results the sensitivity of RCfr13 I to methylation by dcm methylase of E.coli in overlapping sites is deduced.

Bacteriophage lambda↗
PubMed1985

Analysis of products of DNA modification by methylases: a procedure for the determination of 5- and N4-methylcytosines in DNA.

Although many different methods are used for the identification of methylated heterocyclic bases in DNA not all of them possess the ability to discriminate N4-methylcytosine (m4C) and 5-methylcytosine (m5C). Therefore, some of the methods need additional reexamination. This paper reinvestigates some chromatographic systems (thin-layer chromatography, paper chromatography, electrophoresis) most widely used in the analysis of minor bases occurring in nucleic acids according to their ability to separate m4C and m5C. A simple procedure for the preparation of the sample and a chromatographic system for its analysis was developed. The recommended chromatographic systems may be used for the simultaneous separation of not only of m4C and m5C but also both methylated cytosines together with N6-methyladenine and 7-methylguanine.

5-Methylcytosine↗
PubMed1982

A new restriction endonuclease from Citrobacter freundii.

CfrI, a new restriction endonuclease of unique substrate specificity, has been isolated from a Citrobacterfreundii strain. The enzyme recognizes a degenerated sequence PyGGCCPu in double-strand DNA and cleaves it between Py and G residues to yield 5' -protruding tetranucleotide ends GGCC.

Base Sequence↗