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1.  Comparison of the polyoma virus early and late promoters by transcription in vitro. 
Nucleic Acids Research  1982;10(3):871-887.
Polyoma virus DNA was transcribed in the HeLa whole cell extract in vitro system (1). Early region transcripts with the same 5'-ends as in vivo mRNAs, located 31 +/- 2bp from 'TATA'-boxes, were synthesized by RNA polymerase II. Sequences sufficient for efficient expression of the early promoter were present in a substitution mutant lacking viral DNA from a position 55bp before the principal cap sites. Late region transcripts were synthesised inefficiently. Only one (at nt5129 +/- 2) of the many late mRNA cap sites functioned as an in vitro initiation point. This was the one 5'-end located 31 +/- 2bp from a sequence resembling the 'TATA' consensus. The proportion of late to early region RNA polymerase II transcripts decreased dramatically at suboptimal template concentrations. An hypothesis to explain the regulation of late gene expression in vivo based on these results is proposed. A linear templates were transcribed only by RNA polymerase II, transcripts with the same sense as late mRNAs and 5'-ends at nt5076 +/- 2 were produced from superhelical template by an alpha amanitin resistant enzyme.
PMCID: PMC326208  PMID: 6174941
2.  Caffeine inhibits excision of 7-bromomethylbenz (a) anthracene-DNA adducts from exponentially growing but not from stationary phase Chinese hamster cells. 
Nucleic Acids Research  1978;5(12):4795-4803.
Excision of 7-bromomethylbenz(a)anthracene (7-BMBA)-DNA adducts from exponentially growing cultures of Chinese hamster V79-379A cells followed logarithmic kinetics with a half of approximately 20 hrs. Post-treatment incubation in the presence of a sub-toxic concentration of caffeine markedly reduced this loss. Caffeine brought about a concomitant increase in overall DNA synthetic rate in treated exponential cultures. Excision in stationary, non-DNA-replicating cultures, was slower and caffeine did not affect this reduced rate of excision. These findings lend support to a previous proposition that the caffeine-induced inhibition of elongation of nascent DNA on a template containing chemical lesions results in an interference with the excision repair mechanism that removes these lesions.
PMCID: PMC342789  PMID: 745993
3.  The bacteriophage lambda O replication protein: isolation and characterization of the amplified initiator. 
Nucleic Acids Research  1983;11(21):7435-7452.
The bacteriophage lambda O protein participates in the initiation of lambda DNA replication. The lambda O gene was cloned into plasmid pKC30 such that its expression was controlled by the lambda PL promoter. A lambda prophage-coded thermosensitive cI repressor was used to regulate transcription of the cloned O gene. Thermal inactivation of the lambda cI repressor resulted in overproduction of the O protein until it constituted approximately 20% of the total cellular protein of Escherichia coli. A simple three-step purification protocol was developed that yields several milligrams of homogeneous O protein per gram of cell paste. The precise position of the O gene in the known lambda DNA sequence was identified from the amino-terminal sequence of the isolated O protein. Purified O protein stimulated the replication of plasmid lambda dv DNA in vitro and specifically bound to duplex DNA fragments carrying the lambda replication origin.
PMCID: PMC326494  PMID: 6316261
4.  Interaction of novel bis(platinum) complexes with DNA. 
Nucleic Acids Research  1989;17(23):9719-9733.
Bis(platinum) complexes [[cis-PtCl2(NH3)]2H2N(CH2)nNH2] are a novel series of potential anticancer agents in which two cis-diamine(platinum) groups are linked by an alkyldiamine of variable length. These complexes are potentially tetrafunctional, a unique feature in comparison with known anticancer agents. Studies of DNA interactions of bis(platinum) complexes in comparison with cisplatin demonstrate significant differences. Investigations of interstrand crosslink formation in which crosslinking of a short DNA fragment is detected by gel electrophoresis under denaturing conditions demonstrate that interstrand crosslinks are 250 fold more frequent among bis(platinum) adducts than among cisplatin-derived adducts under the conditions examined. These investigations indicate that bis(platinum) adducts contain a high frequency of structurally novel interstrand crosslinks formed through binding of the two platinum centers to opposite DNA strands. Unlike cisplatin, bis(platinum) complex binding does not unwind supercoiled DNA. Studies with the E. coli UvrABC nuclease complex demonstrate that both linear and supercoiled DNA containing bis(platinum) adducts are subject to incision by the repair enzyme complex. Initial studies using UvrABC nuclease as a probe to define the base and sequence specificity for bis(platinum) complex binding suggest that the specificity of the bis(platinum)s is similar, but not identical, to that of cisplatin.
PMCID: PMC335209  PMID: 2690006
5.  A potential stem-loop structure and the sequence CAAUCAA in the transcript are insufficient to signal rho-dependent transcription termination at lambda tR1. 
Nucleic Acids Research  1984;12(2):1287-1299.
It has been suggested that a sequence in the RNA transcript that can form a stem and loop structure, followed by the sequence CAAUCAA, is the signal for rho-dependent transcription termination. We tested this hypothesis by synthesizing a DNA duplex whose sequence corresponds to a region of the lambda tR1 terminator that contains these structural features. We cloned this synthetic DNA fragment under the control of the lacUV5 promoter, and showed that it does not cause rho-dependent termination in vitro. RNA polymerase pauses during in vitro transcription across the synthetic sequence, although less efficiently than at the corresponding sequence on the lambda template. No rho-mediated termination was detected even under conditions that prolonged transcriptional pausing at the synthetic site, indicating that the synthetic sequence is defective as a transcript release site. We suggest that unlike rho-independent terminators, rho-dependent terminators require sequences in addition to those immediately before the sites of termination.
PMCID: PMC318573  PMID: 6320123

Results 1-5 (5)