Accurate cell division requires the proper assembly of high-order septin structures. In fission yeast (Schizosaccharomyces pombe), Spn1-Spn4 are assembled into a primary septin ring at the division site, and the subsequent recruitment of Mid2 to the structure results in a stable septin ring. However, not much is known about the regulation of this key process. Here, we found that deletion of Spt20, a structural subunit of the Spt-Ada-Gcn5-acetyltransferase (SAGA) transcriptional activation complex, caused a severe cell separation defect. The defect was mainly due to impaired septin ring assembly, as 80% of spt20 Delta cells lost septin rings at the division sites. Spt20 regulates septin ring assembly partially through the transcriptional activation of mid2(+). Spt20 also interacted with Spn2 and Mid2 in vitro and was associated with other components of the ring in vivo. Spt20 colocalized with the septin ring, but did not separate when the septin ring split. Importantly, Spt20 regulated the stability of the septin ring and was required for the recruitment of Mid2. The transcription-dependent and -independent roles of Spt20 in septin ring assembly highlight a multifaceted regulation of one process by a SAGA subunit.
[1]Sch Life Sci, State Key Lab Genet Engn, Shanghai 200433, Peoples R China;
[2]Inst Biomed Sci, Shanghai 200433, Peoples R China;
[3]Fudan Univ, State Key Lab Surface Phys, Shanghai 200433, Peoples R China;
[4]Fudan Univ, Dept Phys, Shanghai 200433, Peoples R China;
[5]Shanghai Engn Res Ctr Ind Microorganisms, Shanghai 200433, Peoples R China;
[6]Shanghai Collaborat Innovat Ctr Biomfg Technol, Shanghai 200237, Peoples R China
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