The kinetic landscape and interplay of protein networks in cytokinesis

Abstract

Summary Cytokinesis is executed by protein networks organized into functional modules. Individual proteins within each module have been characterized to various degrees. However, the collective behavior and interplay of the modules remain poorly understood. In this study, we conducted quantitative time-lapse imaging to analyze the accumulation kinetics of more than 20 proteins from different modules of cytokinesis in budding yeast. This analysis has led to a comprehensive picture of the kinetic landscape of cytokinesis, from actomyosin ring (AMR) assembly to cell separation. It revealed that the AMR undergoes biphasic constriction and that the switch between the constriction phases is likely triggered by AMR maturation and primary septum formation. This analysis also provided further insights into the functions of actin filaments and the transglutaminase-like protein Cyk3 in cytokinesis and, in addition, defined Kre6 as the likely enzyme that catalyzes β-1,6-glucan synthesis to drive cell wall maturation during cell growth and division.

Defining Functions of Mannoproteins in Saccharomyces cerevisiae by High-Dimensional Morphological Phenotyping

“…Glucanases are localized at the site of division in cytokinesis. To understand the precise timing of the function of glucanases in cell separation, we tagged cluster V gene products with GFP and performed quantitative time-lapse imaging to obtain information on real-time protein abundance at the division site ( Figure 4 ) [ 28 ]. The accumulation peaks of both GFP-Egt2 and Dse2-GFP occurred after those of two secondary septum (SS)-forming enzymes, GFP-Fks1 and Chs3-GFP, suggesting that cluster V genes likely function after SS formation.…”

“…All new constructs were validated via sequencing performed at the DNA Sequencing Facility, University of Pennsylvania. The plasmids pFA6a-GFPEnvy-KanMX6, pFA6a-link-GFPEnvy-KanMX6, and pRS316-ENVY-FKS1(1-789) were described previously [ 28 ]. The plasmids bWL715 (pHIS3p:mRuby2-Tub1+3’UTR::HPH [ 29 ]) and pFA6a-URA3-KanMX6 [ 30 ] were generous gifts from Wei-Lih Lee (Dartmouth College) and John Pringle (Stanford University), respectively.…”

PP2A-Cdc55 phosphatase regulates actomyosin ring contraction and septum formation during cytokinesis

“…Cytokinetic regulatory proteins such as Iqg1, Hof1, Inn1 and Cyk3 are recruited at the AMR [6,[13][14][15], which mediate the activation of the chitin synthase II, Chs2 [6,[16][17][18]. Chs2 synthesizes the primary septum (PS), concomitantly with AMR constriction [19,20], and drives the second part of its contraction [21]. These proteins are part of the Ingression Progression Complexes (IPCs) [17,22], which coordinates primary septum formation, actomyosin ring contraction and ingression of the plasma membrane at the division site [16,17,[23][24][25][26].…”

PP2A-Cdc55 phosphatase coordinates actomyosin ring contraction and septum formation during cytokinesis

“…Myo1, together with actin filaments and the essential and regulatory myosin light chains Mlc1 and Mlc2, shape the actomyosin ring (AMR) [5,[8][9][10]. The AMR leads to the furrow ingression through its contraction and constriction [11,12].Cytokinetic regulatory proteins such as Iqg1,Hof1, Inn1 and Cyk3 are recruited at the AMR [6,[13][14][15], which mediate the activation of the chitin synthase II, Chs2[6,[16][17][18].Chs2 synthesizes the primary septum (PS), concomitantly with AMR constriction [19,20], and drives the second part of its contraction [21]. These proteins are part of the Ingression Progression Complexes (IPCs) [17,22], which coordinates…”

“…Chs2 synthesizes the primary septum (PS), concomitantly with AMR constriction [19,20], and drives the second part of its contraction [21]. These proteins are part of the Ingression Progression Complexes (IPCs) [17,22], which coordinates…”