Genetic mapping of the amino-terminal domain of bacteriophage T4 DNA polymerase

Journal Article · Sun Mar 01 04:00:00 EST 1987 · Genetics; (United States)

OSTI ID:6869965

Hughes, M B; Yee, A M.F.; Dawson, M; Karam, J

The authors have cloned in bacterial plasmids about 99% of the structural gene for the this enzyme (T4 gene 43). The gene was cloned in six contiguous 5'-terminal DNA fragments that defined seven intragenic mapping regions. Escherichia coli hosts harboring recombinant plasmids carrying the gene 43 subsegments were used in marker-rescue experiments that assigned a large number of ts and nonsense polymerase mutations to different physical domains of the structural gene. Conspicuously, only one missense mutation in a large collection of mutants mapped in the 5'-terminal 450 base-pair segment of the approximately 2700 base-pair gene. To test if this indicated a DNA polymerase domain that is relatively noncritical for biological activity, the authors mutagenized a recombinant plasmid carrying this 5'-terminal region and generated new conditional-lethal mutations that mapped therein. They identified five new ts sites, some having mutated at high frequency (nitrosoguanidine hot spots). New ts mutations were also isolated in phage genes 62 and 44, which map upstream of gene 43 on the T4 chromosome. A preliminary examination of physiological consequences of the ts gene 43 mutations showed that they exhibit effects similar to those of ts lesions that map in other gene 43 segments: some were mutators, some derepressed gene 43 protein synthesis and they varied in the severity of their effects on T4-induced DNA synthesis at nonpermissive temperatures.

• Research Organization: Medical Univ. of South Carolina, Charleston
• OSTI ID: 6869965
• Journal Information: Genetics; (United States), Journal Name: Genetics; (United States) Vol. 115:3; ISSN GENTA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
550400 -- Genetics
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BACTERIOPHAGES
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CELL CONSTITUENTS
CHROMOSOMES
CLONING
DNA POLYMERASES
DNA REPAIR
ENZYMES
ESCHERICHIA COLI
GENE MUTATIONS
GENES
GENETIC MAPPING
MAPPING
MICROORGANISMS
MUTATION FREQUENCY
MUTATIONS
NUCLEOTIDYLTRANSFERASES
PARASITES
PHOSPHORUS-GROUP TRANSFERASES
PLASMIDS
POLYMERASES
RECOVERY
REPAIR
TRANSFERASES
VIRUSES