Autoregulation of phage mu transposase at the level of translation.
The bacteriophage Mu A and B genes, which lie adjacent to each other and are colinear on the phage genome, encode proteins that catalyze efficient transposition of Mu DNA. We show that the molar ratio of A and B proteins is approximately 1:20 in extracts prepared after induction of cells containing a Mu lysogen or a plasmid carrying the Mu fragment that encompasses A and B. In cells harboring the cloned genes, the proteins are synthesized from a single transcript. Pulse-chase experiments demonstrate that the lower amounts of A protein are not from preferential turnover of this protein. This suggests the existence of a post-transcriptional mechanism to down-regulate A protein synthesis. From an analysis of the activity of several beta-galactosidase fusions to A protein, we infer that A protein may repress its own translation. By an agarose gel mobility-shift assay, we demonstrate that purified A protein binds specifically in vitro to its mRNA.
Parsons
R L
RL
Research Institute of Scripps Clinic, Department of Molecular Biology, La Jolla, CA 92037.
Harshey
R
R
D010583:Bacteriophage mu / Q000201:enzymology / Q000235:genetics*; D005814:Genes, Viral; D006706:Homeostasis; D009713:Nucleotidyltransferases / Q000235:genetics*; D014176:Protein Biosynthesis; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification; D014158:Transcription, Genetic; D019895:Transposases; D014764:Viral Proteins / Q000096:biosynthesis; D014775:Virus Activation; D001616:beta-Galactosidase / Q000096:biosynthesis
D011993:Recombinant Fusion Proteins; D014764:Viral Proteins; D009713:Nucleotidyltransferases; D019895:Transposases; D001616:beta-Galactosidase