A partially functional 245-amino-acid internal deletion derivative of Escherichia coli sigma 70

Two hundred forty-five consecutive amino acids of the sigma 70 subunit of Escherichia coli RNA polymerase are not conserved in the homologous protein of Bacillus subtilis. We show that their deletion from a sigma 70-32 hybrid protein caused no severe loss of function in vivo, while sigma 70 itself retained considerable function in vitro.