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Two Haemophilus influenzae Rd genes that complement the recA-like mutation rec-1
G J Barcak1, J F Tomb, C S Laufer
1Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Journal of Bacteriology
|May 1, 1989
Summary
Two Haemophilus influenzae Rd genes, fec and rec, were identified and cloned. These genes restored DNA repair and UV resistance in mutant strains, indicating their crucial roles in genetic stability.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- The recA-like mutation rec-1 in Haemophilus influenzae Rd causes pleiotropic defects.
- Understanding DNA repair mechanisms is crucial for bacterial genetic stability.
Purpose of the Study:
- To identify and characterize genes in Haemophilus influenzae Rd that complement rec-1 mutation defects.
- To investigate the roles of these genes in DNA repair and resistance to DNA damage.
Main Methods:
- Gene cloning using complementation of bacteriophage lambda Fec- phenotype and Southern hybridization with recA-like gene probes.
- Characterization of cloned genes through insertion/deletion mutagenesis and subcloning.
- Analysis of gene homology and polypeptide products.
Main Results:
- Two genes, fec and rec, were isolated on EcoRI restriction fragments.
- Both cloned genes restored UV irradiation resistance, transformation efficiency, and prophage release in rec-1 mutant strains.
- The fec and rec genes encoded a 38,000-dalton polypeptide and showed similar, but not identical, DNA sequences.
Conclusions:
- The identified fec and rec genes are essential for DNA repair and genetic stability in Haemophilus influenzae Rd.
- These genes represent novel components of the bacterial DNA repair system, homologous to recA.