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The genomic DNAs of the eukaryotic Chlorella-like green alga, strain NC64A, and eleven of its viruses all contain significant levels of 5-methyldeoxycytidine. In addition, the host DNA as well as six of the viral DNAs also contain N6-methyldeoxyadenosine. At least some of the methylated bases in the host reside in different base sequences than the… (More)
We examined the DNA of Saccharomyces cerevisiae by both HpaII-MspI restriction enzyme digestion and high-performance liquid chromatography analysis for the possible presence of 5-methylcytosine. Both of these methods failed to detect cytosine methylation within this yeast DNA; i.e., there is less than 1 5-methylcytosine per 3,100 to 6,000 cytosine residues.
Expression of the bacteriophage Mu mom gene is under tight regulatory control. One of the factors required for mom gene expression is the trans-acting function (designated Dad) provided by another Mu gene. To facilitate studies on the signals mediating mom regulation, we have constructed a mom-lacZ fusion plasmid which synthesizes beta-galactosidase only… (More)
The bacteriophage Mu mom gene encodes a novel DNA modification that protects the viral genome against a wide variety of restriction endonucleases. Expression of mom is subject to a series of unusual regulatory controls. Transcription requires the action of a phage-encoded protein, C, which binds (probably as a dimer) the mom promoter from -33 to -52 (with… (More)
We have analyzed the nature/content of methylated bases in the nuclear DNA of three unicellular eucaryotes. The pattern of methylation was different for each of the three organisms studied: Saccharomyces cerevisiae contained only 5-methylcytosine; Tetrahymena pyriformis contained only N6-methyladenine; and Chlamydomonas reinhardi contained both modified… (More)
Transcription of the phage Mu com/mom operon is trans-activated by another phage gene product, C, a site-specific DNA binding protein. To gain insight into the mechanism by which C activates transcription, we carried out footprinting analyses of Escherichia coli RNA polymerase (= RNAP) binding to various com-lacZ fusion plasmids. KMnO4-sensitive sites… (More)
The bacteriophage Mu C gene encodes a 16.5 kDa site-specific DNA binding protein that is a transcriptional activator of the four "late" promoters, Pmom, Plys, PI and PP. A symmetrical consensus C recognition sequence, TTAT[N5-6]ATAA, containing an inverted tetrad repeat separated by a spacer of five to six G+C-rich nucleotides, has been proposed. To… (More)
Properties of a mutant bacteriophage T2 DNA [N:(6)-adenine] methyltransferase (T2 Dam MTase) have been investigated for its potential utilization in RecA-assisted restriction endonuclease (RARE) cleavage. Steady-state kinetic analyses with oligonucleotide duplexes revealed that, compared to wild-type T4 Dam, both wild-type T2 Dam and mutant T2 Dam P126S had… (More)
A nomenclature is described for restriction endonucleases, DNA methyltransferases, homing endonucleases and related genes and gene products. It provides explicit categories for the many different Type II enzymes now identified and provides a system for naming the putative genes found by sequence analysis of microbial genomes.
Rhizobium phage RL38JI DNA is resistant to cleavage by a variety of restriction endonucleases, and is only partially sensitive to digestion by pancreatic DNase I or by micrococcal nuclease. We have found that a mixture of DNase I, P1 nuclease, and bacterial alkaline phosphatase will quantitatively digest RL38JI DNA to deoxyribonucleosides. HPLC analysis… (More)