Mutations that alter the helix‐turn‐helix region of thespollACprotein: aBacillus subtilissporulation‐specific sigma factor

摘要

SummaryIt has previously been shown thatspollAC561, a mutation that diminishes the incidence of sporulation by more than six orders of magnitude, alters the residue at position 13 of the helix‐turn‐helix region of the sporulation‐specific sigma factor encoded byspoll ACfrom valine to methionine (Yudkin, 1987b). We have now found that four spontaneous revertants, which sporulate at an incidence of 30‐60, all contain transitions within the codon that was altered byspo‐561. The mutant methionine is replaced by isoleucine in two revertants, and by threonine in the