Donald R. Helinski
University of California, San Diego
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Primary Section: 26, Genetics Secondary Section: 44, Microbial Biology Membership Type:
Member
(elected 1980)
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Research Interests
My research efforts are focused on the genetic and biochemical basis of stable maintenance of plasmids in bacteria. Particular attention is placed on the biochemical interactions between a replication initiation protein (rep) and an origin of replication (oriV) of a broad-host range plasmid (RK2) that is capable of replication and stable maintenance in virtually all Gram-negative bacteria. A number of mutants of the rep protein have been isolated and purified to determine various levels of interaction between the initiation protein and the replication origin including binding, replication control, interaction with bacterial host protein, and activation of helicase activity. In addition we have observed that the multiple copies of plasmid RK2 are not randomly distributed but are clustered as a single focus or a few foci at preferred positions in the cell. Using fluorescent microscopy techniques we are attempting to identify the plasmid specified and the bacterial host proteins and structures that are responsible for clustering of plasmid molecules and the positioning of these clusters in a host cell.
