GENETIC AND BIOCHEMICAL ANALYSIS OF THE OVERPRODUCTION OF MEMBRANE PROTEINS, MP32 AND MP18, IN A BACILLUS SUBTILIS STRAIN CARRYING THE MPO-1 MUTATION

Abstract

The membrane proteins MP32 and MP18 (molecular weights 32, 000 and 18, 000) increased extensively during sporulation in the mpo-1 mutant of Bacillus subtilis. Pulse-labeling experiments suggested that the increase in MP32 and MP18 during sporulation was due to the promoted de novo synthesis of these proteins. Neither spo0 mutations, nor the release from catabolite repression, affected the increase in MP32 and MP18 during
sporulation. To clarify the relationship between the mpo mutation and the synthesis of MP32 and MP18, a mpo⁺/mpo-1 hetero merodiploid strain was constructed using the trpE26 mutation. In this strain, there was no overproduction of MP32 or MP18, indicating that the mpo⁺ is dominant to mpo-1, and that the mpo gene product may regulate negatively the synthesis of MP32 and MP18.