Gene pvuIIW: a possible modulator of PvuII endonuclease subunit association.
The PvuII restriction-modification system has been found to contain three genes which code for a DNA methyltransferase (MTase), a restriction endonuclease (ENase) and a small protein required for expression of the ENase-encoding gene. In addition, there is a small open reading frame (ORF) within and opposite to the MTase-encoding gene. The region containing this ORF is transcribed, and the ORF has an excellent Shine-Dalgarno sequence with an ATA start codon. A closely related ORF is present in the SmaI system. The 28-amino-acid (aa) predicted peptide from the PvuII ORF resembles a region of the PvuII ENase at the dimer interface. We have cloned this ORF, giving it an ATG start codon and putting it under the control of an inducible promoter: induction leads to a slight but significant decrease in restriction of bacteriophage lambda. We also have obtained the 28-aa synthetic peptide, and are exploring the possibility that it modulates ENase subunit association. While this peptide has no detectable effect on dimeric PvuII ENase, it inhibits renaturation of urea-denatured ENase in a concentration-dependent manner. The ORF may represent an additional safeguard during establishment of the PvuII restriction-modification system in a new host cell, helping to delay the appearance of active ENase dimers, while the MTase accumulates and protects the host chromosome.
Adams
G M
GM
Department of Microbiology, Medical College of Ohio, Toledo 43699-0008, USA.
Blumenthal
R M
RM
D000595:Amino Acid Sequence; D001483:Base Sequence; D015252:Deoxyribonucleases, Type II Site-Specific / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D007700:Kinetics; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017433:Protein Structure, Secondary; D014158:Transcription, Genetic
D046911:Macromolecular Substances; C025630:CAGCTG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific