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The 5′ to 3′ exonuclease activity of DNA polymerase I is essential for Streptococcus pneumoniae
Author(s) -
Díaz Asunción,
Lacks Sanford A.,
López Paloma
Publication year - 1992
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1992.tb01759.x
Subject(s) - biology , streptococcus pneumoniae , exonuclease , dna polymerase , polymerase , dna , microbiology and biotechnology , genetics , virology , antibiotics
Summary Three different mutations were introduced in the polA gene of Streptococcus pneumoniae by chromosomal transformation. One mutant gene encodes a truncated protein that possesses 5′ to 3′ exonuclease but has lost polymerase activity. This mutation does not affect cell viability. Other mutated forms of polA that encode proteins with only polymerase activity or with no enzymatic activity could not substitute for the wild‐type polA gene in the chromosome unless the 5′ to 3′ exonuclease domain was encoded elsewhere in the chromosome. Thus, it appears that the 5′ to 3′ exonuclease activity of the DNA polymerase I is essential for cell viability in S. pneumoniae. Absence of the polymerase domain of DNA polymerase I slightly diminished the ability of S. pneumoniae to repair DNA lesions after ultraviolet irradiation. However, the polymerase domain of the pneumococcal DNA polymerase I gave almost complete complementation of the polA5 mutation in Escherichia coli with respect to resistance to ultraviolet irradiation.