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The Bacillus subtilis chromatin‐associated protein Hbsu is involved in DNA repair and recombination
Author(s) -
Fernández Silvia,
Rojo Fernando,
Alonso Juan C.
Publication year - 1997
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 - 10.1046/j.1365-2958.1997.3061670.x
Subject(s) - biology , homologous recombination , dna repair , microbiology and biotechnology , dna , flp frt recombination , mutant , replication protein a , in vitro recombination , genetics , chromatin , mutation , gene , bacillus subtilis , dna repair protein xrcc4 , genetic recombination , recombination , nucleotide excision repair , dna binding protein , peptide sequence , molecular cloning , transcription factor , bacteria
Summary The Bacillus subtilis hbs gene encodes an essential chromatin‐associated protein termed Hbsu. Hbsu, the counterpart of the Escherichia coli HU protein, binds DNA in a non‐specific way but has a clear preference for bent, kinked or altered DNA sequences. To investigate the role of Hbsu in DNA repair and DNA recombination we have constructed a series of site‐directed mutants in the hbs gene and used these mutant genes to substitute the wild‐type chromosomal hbs gene. The hbs47 mutation, which codes for a mutant protein in which residue Phe‐47 has been replaced by Trp, does not cause any discernible phenotype. Additional substitution of residue Arg‐55 by Ala (hbs4755 mutation) rendered cells deficient in DNA repair, homologous recombination and (i protein‐mediated site‐specific recombination. We have also tested the effect on DNA repair of the hbs4755 mutation in combination with mutations in different functions of homologous DNA recombination (recA, recF, recG, recti and addAB). The hbs4755 mutation did not modify the sensitivity of recH and addAB cells to the DNA‐damaging agents methylmethane sulphonate (MMS) or 4‐nitroquinoline‐1‐oxide (4NQO), and it only marginally affected recF and recG cells. The hbs4755 mutation blocked intermolecular recombination in recH cells and markedly reduced it (20‐ to 50‐fold) in recF and recG cells, but had no effect on addAB cells. Taken together, these data indicate that the Hbsu protein is required for DNA repair and for homologous DNA recombination.