Genetic and biochemical analysis of the overproduction of membrane proteins, MP32 and MP18, in a Bacillus subtilis strain carrying the MPO-1 mutation

SHIGENOBU MATSUZAKI, SAKUZO FUKUI, YASUO KOBAYASHI
1988 Journal of General and Applied Microbiology  
The membrane proteins MP32 and MP 18 (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 MP 18 during sporulation was due to the promoted de novo synthesis of these proteins. Neither spoo mutations, nor the release from catabolite repression, affected the increase in MP32 and MP 18 during sporulation. To clarify the relationship between the mpo mutation and the
more » ... po mutation and the synthesis of MP32 and MP 18, a mpo +/mpo-1 hetero merodiploid strain was constructed using the trpE26 mutation. In this strain, there was no overproduction of MP32 or MP 18, indicating that the mpo + is dominant to mpo-1, and that the mpo gene product may regulate negatively the synthesis of MP32 and MP18. The sporulation of Bacillus subtilis is a simple model for studying cell differentiation. The sporulation process is accomplished through seven morphological steps (1). Early stages involve the asymmetric septation and engulfment of cytoplasmic membrane, which result in a forespore surrounded by two unit membranes apparently of opposite polarity. The membrane protein composition of sporulating cells is different from that of the vegetative cells (2, 3). Furthermore, several spoo mutations which block sporulation at stage 0-I alter membrane protein ' On leave from the
doi:10.2323/jgam.34.367 fatcat:b2u4hpcvfzb67dlxptr6nbjaw4