Pl. Tavormina et al., IDENTIFYING INTERACTING REGIONS IN THE BETA-SUBUNIT OF ESCHERICHIA-COLI RNA-POLYMERASE, Journal of Molecular Biology, 258(2), 1996, pp. 213-223
Numerous physical and genetic approaches have identified residues in t
he alpha, beta, beta' and sigma subunits of Escherichia coli RNA polym
erase that are involved in transcriptional processes; in contrast, rel
atively little data exist to demonstrate interacting regions within or
between the subunits themselves. As a means of identifying regions in
the beta subunit that may interact, we have sought intragenic suppres
sor mutations of a class of elongation-defective and termination-profi
cient inviable rpoB alleles that affect highly conserved residues. We
obtained intragenic allele-specific suppressors of GD566 (located in c
onserved region D) and AV676 (located in conserved region E). With one
exception, these allele-specific suppressors also map to highly conse
rved regions of the beta subunit. Allele specific suppression is a gen
etic criterion for protein-protein interaction. Moreover, the function
al properties of the mutants suggests that suppression is likely to re
sult from protein-protein interaction rather than from functional comp
ensation. Our suppression studies provide evidence for the interaction
of conserved regions B and D as well as conserved regions E and H of
the beta polypeptide. We suggest that these, as well as other conserve
d regions of the beta polypeptide, may interact with each other to pro
vide a framework for the function of the enzyme. (C) 1996 Academic Pre
ss Limited