The bdellovibrios are gram-negative bacteria which prey upon other gram-negative bacteria. They are found in a variety of habitants and likely represent a significant biological control of gram-negative bacteria in the environment. They attach to the surface of their prey, traverse the outer membrane and peptidoglycan, and establish residence in the periplasmic space. Here they execute a program of highly efficient biochemical processes which results in the proliferation of the bdellovibrios at the expense of the prey. The proposed research is a continuation of recent studies which show that Bdellovibrio recruits intact outer membrane proteins from the prey. These prey-derived proteins are inserted into the outer membrane of the Bdellovibrio. The mechanism accounting for this novel process of protein mobilization and relocalization will be examined by attempting to select mutants defective in this process, and by employing E. coli prey which express structurally altered porins. If mutant proteins are found which fail to be acquired by the bdellovibrios, the structural alterations in the proteins will be assessed from peptide maps and from peptide sequencing techniques. The possible role of donor and recipient membrane fluidities also will be examined to assess their significance in the relocalization process. The outlined experiments along with a series of descriptive experiments designed to correlate protein acquisition with other known biochemical events of the Bdellovibrio life-cycle are expected to provide sufficient information to permit the formulation of hypothetical mechanisms which can be tested experimentally. This research is anticipated to provide a unique approach to evaluating structure-function relationships in membrane proteins. Additionally, it is anticipated that the proposed research will make a significant contribution to revealing the biochemical basis of predation by Bdellovibrio.
