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ComEA is a DNA receptor for transformation of competent Bacillus subtilis
Author(s) -
Provvedi R.,
Dubnau D.
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01170.x
Subject(s) - biology , bacillus subtilis , dna , biochemistry , dna binding protein , operon , hmg box , dna binding domain , binding domain , dna binding site , microbiology and biotechnology , binding site , bacteria , genetics , gene , escherichia coli , transcription factor , gene expression , promoter
Competent cells of Bacillus subtilis efficiently bind and internalize DNA. ComEA and the seven proteins encoded by the comG operon are required in vivo for the binding step. We show here that ComEA, a bitopic membrane protein, is itself capable of high‐affinity DNA binding. A domain necessary for DNA binding is located at the C‐terminus of ComEA. Proteins with similar 60–80 amino acid residue domains are widespread among bacteria and higher organisms. ComEA shows a marked preference for double‐stranded DNA and can bind to oligomers as small as 22 bp in length. DNA binding by ComEA exhibits no apparent base sequence specificity. Using a membrane vesicle DNA‐binding assay system we show that in the absence of cell wall, ComEA is still required for DNA binding, whereas the requirement for the ComG proteins is bypassed. We conclude that the ComG proteins are needed in vivo to provide access of the binding domain of ComEA to exogenous DNA. Possible specific roles for the ComG proteins are discussed.