Open AccessThe Role of the Components δ and y of the DNA‐Dependent RNA Polymerase of Lactobacillus curvatus in Promotor Selection
Author(s) -
GIERL Alfons,
ZILLIG Wolfram,
STETTER Karl Otto
Publication year - 1982
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1982.tb06648.x
Subject(s) - sigma factor , rna polymerase , microbiology and biotechnology , dna , transcription (linguistics) , promoter , biology , polymerase , specificity factor , rna , chemistry , genetics , gene , gene expression , linguistics , philosophy
An average of 0.44 molecule each of the initiation factor δ and the RNA polymerase binding protein y and 0.54 molecule of the subunit y per molecule of Lactobacillus curvatus DNA‐dependent RNA polymerase have been found in the cell. Free factor y displaces δ from free holo enzyme, Eδ. The formation of a binary complex from Ey, free δ, and poly[d(A‐T)], leads to immediate release of factor y. The release of the δ factor occurs upon the transition of the binary to a ternary complex. A mixture of E and δ forms binary complexes with all T7 DNA Hpa II restriction fragments. In contrast a mix‐ ture of Ey and δ binds selectively to promoter‐containing DNA fragments, indicating that the stimulatory effect of y on transcription is due to an increase in the rate of promoter selection. The same RNA products are synthesised by Eδ and by Ey plus δ with T7 DNA as template. Thus the non‐ specific complexes formed by Eδ and T7 DNA are nonproductive. On the basis of these findings we propose a model for the transcription cycle in Lactobacillus curvatus .