DcrA and dcrB Escherichia coli genes can control DNA injection by phages specific for BtuB and FhuA receptors.

We had previously shown that the Escherichia coli proteins DcrA (SdaC) and DcrB, located, respectively, in the inner membrane and periplasm, are involved in the early development of virulent bacteriophage C1, which recognises BtuB as an outer membrane receptor. In the present work it is demonstrated that the DcrA and DcrB proteins, coordinately with another outer membrane receptor protein, FhuA, are also involved in an early stage of development of a newly isolated virulent phage, C6. In both cases, DcrA and DcrB probably are required in the second stage of phage adsorption-the DNA injection process. This means that DcrA and DcrB proteins can participate in phage DNA transport pathways in cooperation with different outer membrane receptors, including FhuA and BtuB. The increased sensitivity of bacterial cells to SDS following C1 and C6 adsorption suggests that adsorption by these phages triggers the opening of diffusion channels through the outer membrane. Our results also indirectly demonstrate that the DcrA and DcrB proteins participate in the opening or formation of these channels.