FIG 7.

Working model of Ali1 adaptor function. We propose that Ali1 (yellow/blue) acts as an adaptor protein to aid in the localization of the Fas1 and Fas2 fatty acid synthase complex (red) to the septum and poles of actively dividing cells, possibly in a ubiquitin-mediated manner through interactions with the E3 ubiquitin ligase Rsp5 (green). This process occurs to help meet the increased, stress-induced need for lipid synthesis and deposition at these sites. In the ali1Δ mutant strain, Fas1 and Fas2 are unable to localize, or are delayed in their localization, to the septum and poles during cell division. As a result, lipid synthesis and deposition at these sites is impaired. This causes localized cell surface defects at the poles in the resulting cells, likely explaining the cytokinesis defects and caffeine sensitivity phenotypes of the ali1Δ mutant.