Molecular cloning of linotte in Drosophila: a novel gene that functions in adults during associative learning.

The linotte (lio) gene was identified in a screen for mutations that disrupted 3 hr memory after olfactory associative learning, without affecting the perception of odors or electroshock. The mutagenesis yielded a transposon-tagged gene disruption, which allowed rapid cloning of genomic DNA. The lio transcription unit was identified via rescue of the lio1 learning/memory defect by induced expression of a lio+ transgene in adults. The perception of odors or electroshock remained normal when the lio+ transgene was expressed in these lio1 flies. Learning/memory remained normal when the lio+ transgene was expressed in wild-type (lio+) flies. The lio gene produces only one transcript, the level of expression of which varies throughout development. Sequence analysis indicates that lio encodes a novel protein.

Interaction of nuclear factor EF-1A with the polyomavirus enhancer region.

Enhancer factor 1A (EF-1A) is a mammalian nuclear protein that previously was shown to bind cooperatively to the repeated core enhancer element I sequence in the adenovirus E1A enhancer region. We now have characterized three binding sites for EF-1A in the polyomavirus A2 (Py) enhancer region. Site 1 resides in the Py A enhancer domain, and sites 2 and 3 reside in the Py B enhancer domain. EF-1A binding to Py site 1 is independent of cooperation with other EF-1A sites or the adjacent binding sites for PEA-1 and PEA-2, two murine nuclear factors that bind in the Py A enhancer domain. EF-1A binding to Py sites 2 and 3, in contrast, is cooperative, similar to the situation previously observed with binding sites in the adenovirus E1A enhancer region. In a transient replication assay, EF-1A site 1 functions synergistically with the PEA-1 and PEA-2 sites in the A enhancer domain to enhance Py replication. The functional cooperativity observed with the EF-1A, PEA-1, and PEA-2 sites in vivo does not reflect cooperative DNA binding interactions, as detected in vitro. Py EF-1A site 1 alone is capable of weakly stimulating Py replication. EF-1A site 1 overlaps with the binding sites for the murine nuclear protein PEA-3 and the ets family of oncoproteins.

Different binding site requirements for binding and activation for the bipartite enhancer factor EF-1A.

The human transcription factor EF-1A binds to the purine-rich E1A core enhancer sequence in the adenovirus E1A and E4 and polyomavirus enhancer regions. The consensus binding site for EF-1A resembles that of members of the ets domain protein family. EF-1A activation of transcription requires a dimeric binding site. Analysis of binding sites containing point mutations revealed that EF-1A binding is determined by the core nucleotides of the binding site, while transcriptional activation is determined both by the core and some peripheral nucleotides that do not affect binding. We have purified EF-1A and analyzed its two constituent subunits, EF-1A alpha and EF-1A beta. EF-1A alpha (MW approximately 60kD) makes the primary DNA contacts. EF-1A beta (MW approximately 50 kD) forms a heteromultimeric complex with EF-1A alpha both in solution and on a dimeric binding site. Binding of both EF-1A subunits is necessary, but not sufficient, for transcriptional activation. We present immunochemical and functional evidence that EF-1A alpha is related to the murine ets-related protein GABP alpha and that EF-1A beta is related to the murine protein GABP beta.