Septin ring assembly is regulated by Spt20, a structural subunit of SAGA complex

Abstract

BSTRACTAccurate 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 spt20D 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.

Expanded Interactome of the Intrinsically Disordered Protein Dss1

“…During mitosis, the septins concentrate at the medial region of the cell to form ring-shaped structures that are binding scaffolds for other proteins. Previous studies have tied Dss1 to the Spt-Ada-Gcn5-acetyltransferase (SAGA) complex ( García-Oliver et al., 2013 ), which regulates septin ring assembly via transcriptional activation of mid2 + ( Lei et al., 2014 ). We did not observe any defects in septin ring formation in the dss1 -null mutant, but we cannot rule out that the role of Dss1 in transcription contributes to the dss1 Δ septation problems.…”

Sgf73, a subunit of SAGA complex, is required for the assembly of RITS complex in fission yeast

“…This study also extends a growing list of the moonlighting functions of SAGA subunits. Besides Sgf73, Spt20, a structural subunit of SAGA, regulates septin ring assembly through physical interactions with septins 42 . p38IP, a human homologue of Spt20, interacts with mammalian (m)Atg9 (ATG9A) and inhibits the trafficking of mAtg9 43 .…”

Transcriptome Analysis of the Japanese Pine Sawyer Beetle, Monochamus alternatus, Infected with the Entomopathogenic Fungus Metarhizium anisopliae JEF-197

“…Recent studies have shown the modulation of pathogenesis and virulence by transcriptional factors of entomopathogenic fungi [ 70 , 71 , 72 ]. Regulation of activation of gene transcription can contribute to toxicity in the host [ 73 , 74 ], while the recQ family helicase is involved in DNA repair and replication [ 75 ]. The increase in expression level of these genes suggests that transcription-, repair-, and replication-related genes play important roles in the pathogenesis and proliferation of the fungus JEF-197 in JPS beetles.…”