A Corynebacterium glutamicum rnhA recG double mutant showing lysozyme-sensitivity, temperature-sensitive growth, and UV-sensitivity.
Corynebacterium glutamicum mutant KY9707 was originally isolated for lysozyme-sensitivity, and showed temperature-sensitive growth. Two DNA fragments from a wild-type C. glutamicum chromosomal library suppressed the temperature-sensitivity of KY9707. These clones also rescued the lysozyme-sensitivity of KY9707, although partially. One of them encodes a protein of 382 amino acid residues, the N-terminal domain of which was homologous to RNase HI. This gene suppressed the temperature-sensitive growth of an Escherichia coli rnhA rnhB double mutant. We concluded that this gene encodes a functional RNase HI of C. glutamicum and designated it as rnhA. The other gene encodes a protein of 707 amino acid residues highly homologous to RecG protein. The C. glutamicum recG gene complemented the UV-sensitivity of E. coli recG258::kan mutant. KY9707 showed increased UV-sensitivity, which was partially rescued by either the recG or rnhA gene of C. gluamicum. Point mutations were found in both recG and rnhA genes in KY9707. These suggest that temperature-sensitive growth, UV-sensitivity, and probably lysozyme-sensitivity also, of KY9707 were caused by mutations in the genes encoding RNase HI and RecG.
Hirasawa
Takashi
T
Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan.
Kumagai
Yutaro
Y
Nagai
Kazuo
K
Wachi
Masaaki
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003352:Corynebacterium / Q000187:drug effects* / Q000201:enzymology / Q000528:radiation effects*; D004265:DNA Helicases / Q000235:genetics*; D017931:DNA Primers; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005819:Genetic Markers; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D009113:Muramidase / Q000494:pharmacology*; D016296:Mutagenesis; D016366:Open Reading Frames; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism; D015183:Restriction Mapping; D016914:Ribonuclease H / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014466:Ultraviolet Rays
D017931:DNA Primers; D005819:Genetic Markers; D011994:Recombinant Proteins; D016914:Ribonuclease H; C078856:ribonuclease HI; D009113:Muramidase; D004265:DNA Helicases