Coordinate eukaryotic gene regulation may be induced by interactions of specific regulatory factors with DNA and protein components of the basal gene promoters. Detachment of the flagella of Chlamydomonas reinhardtii rapidly induces transcription of tubulin and other flagellar genes nearly 10-fold above basal levels of expression, making this an ideal system with which to study such regulatory interactions. To determine DNA sequences required for deflagellation-induced expression tubulin and other non-tubulin flagellar protein genes will be modified for identification, deleted to retain varying lengths of 5' and 3' flanking regions and intervening sequences, and introduced into Chlamydomonas by transformation. Expression of the modified genes will be analyzed in control and deflagellated cells. Regulatory elements will be located by correlating loss of inducibility with specific deletions. Independent confirmation that the regulatory sequences identified in gene sequences identified in gene transfer studies confer inducibility will be obtained by analyzing the interaction of protein factors will these in vivo and in vitro. These studies will provide the basis for analyses of the signalling and regulatory mechanisms coordinating expression of this large, diverse set of flagellar genes in response of deflagellation.
