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Actin and endocytosis in budding yeast.

Goode BL, Eskin JA, Wendland B - Genetics (2015)

Bottom Line: Many critical aspects of the CME mechanism are conserved from yeast to mammals and were first elucidated in yeast, demonstrating that it is a powerful system for studying endocytosis.In this review, we describe our current mechanistic understanding of each step in the process of yeast CME, and the essential roles played by actin polymerization at these sites, while providing a historical perspective of how the landscape has changed since the preceding version of the YeastBook was published 17 years ago (1997).Finally, we discuss the key unresolved issues and where future studies might be headed.

View Article: PubMed Central - PubMed

Affiliation: Brandeis University, Department of Biology, Rosenstiel Center, Waltham, Massachusetts 02454 goode@brandeis.edu bwendland@jhu.edu.

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Arp2/3 complex nucleation-promoting factors (NPFs). The figure depicts three proposed stages of NPF activity. (A) Inhibited NPFs. In earlier stages of patch development well before the arrival of Arp2/3 complex, the NPFs Las17/WASP and Pan1/Intersectin are maintained at patches in an inactive state by direct binding partners and are unable to recruit Arp2/3 complex. (B) Network priming. After subsequent deactivation of their inhibitors, Las17/WASP and Pan1/Intersectin are released to recruit and activate Arp2/3 complex. However, network nucleation also requires priming by one of two proposed mechanisms: (i) the capture or de novo assembly of an initial mother filament, which may depend on the Arp2/3-independent activities of Las17, Pan1, and/or Ysc84/Lsb4, or (ii) the stimulation of unbranched actin nucleation by Arp2/3 complex, as Nolen and colleagues have recently demonstrated can be induced by the S. pombe homolog of Ldb17/DIP/WISH (Wagner et al. 2013). (C) Active nucleation. After the priming stage, the Arp2/3 complex and its NPFs rapidly assemble a densely branched actin-filament network that promotes membrane remodeling. Class I NPFs bind G-actin: Las17/WASP, Vrp1/WIP, and myosin I. Class II NPFs bind F-actin: Pan1/Intersectin and Abp1. Some of the proteins are shown in complexes with their known binding partners. Additional interactions are indicated by dotted lines. Arrows represent stimulatory effects. Illustrations are based on available structural and sequence data. Abbreviations: THATCH, talin-HIP1/R/Sla2p actin-tethering C-terminal homology domain; ANTH, AP180 N-terminal homology domain; F-BAR, FER/Cip4 homology-Bin/Amphiphysin/Rvs domain; µHD, µ homology domain; EH, Eps15 homology domain; LRD, leucine-rich domain; CC, coiled coil; V, verprolin homology motif; C, connector motif; A, acidic motif; SH3, Src homology 3 domain; SHD, Sla1 homology domain; CTR, C-terminal repeats; ADF-H, actin depolymerizing factor homology domain; TH, tail homology domain; WBD, WASP-binding domain; EVH1, Ena/Vasp homology 1 domain; PP, polyproline region.
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fig6: Arp2/3 complex nucleation-promoting factors (NPFs). The figure depicts three proposed stages of NPF activity. (A) Inhibited NPFs. In earlier stages of patch development well before the arrival of Arp2/3 complex, the NPFs Las17/WASP and Pan1/Intersectin are maintained at patches in an inactive state by direct binding partners and are unable to recruit Arp2/3 complex. (B) Network priming. After subsequent deactivation of their inhibitors, Las17/WASP and Pan1/Intersectin are released to recruit and activate Arp2/3 complex. However, network nucleation also requires priming by one of two proposed mechanisms: (i) the capture or de novo assembly of an initial mother filament, which may depend on the Arp2/3-independent activities of Las17, Pan1, and/or Ysc84/Lsb4, or (ii) the stimulation of unbranched actin nucleation by Arp2/3 complex, as Nolen and colleagues have recently demonstrated can be induced by the S. pombe homolog of Ldb17/DIP/WISH (Wagner et al. 2013). (C) Active nucleation. After the priming stage, the Arp2/3 complex and its NPFs rapidly assemble a densely branched actin-filament network that promotes membrane remodeling. Class I NPFs bind G-actin: Las17/WASP, Vrp1/WIP, and myosin I. Class II NPFs bind F-actin: Pan1/Intersectin and Abp1. Some of the proteins are shown in complexes with their known binding partners. Additional interactions are indicated by dotted lines. Arrows represent stimulatory effects. Illustrations are based on available structural and sequence data. Abbreviations: THATCH, talin-HIP1/R/Sla2p actin-tethering C-terminal homology domain; ANTH, AP180 N-terminal homology domain; F-BAR, FER/Cip4 homology-Bin/Amphiphysin/Rvs domain; µHD, µ homology domain; EH, Eps15 homology domain; LRD, leucine-rich domain; CC, coiled coil; V, verprolin homology motif; C, connector motif; A, acidic motif; SH3, Src homology 3 domain; SHD, Sla1 homology domain; CTR, C-terminal repeats; ADF-H, actin depolymerizing factor homology domain; TH, tail homology domain; WBD, WASP-binding domain; EVH1, Ena/Vasp homology 1 domain; PP, polyproline region.

Mentions: NPFs directly associate with Arp2/3 complex and actin and serve as cofactors in stimulating nucleation. As mentioned above, there are four known NPFs in yeast: (1) Las17/WASP, (2) myosin I (Myo3 or Myo5) in a complex with Vrp1/WIP, (3) Pan1/Intersectin, and (4) Abp1 (Winter et al. 1999; Evangelista et al. 2000; Lechler et al. 2000; Duncan et al. 2001; Goode et al. 2001) (Figure 6). Each of these NPFs localizes to actin patches, binds to actin and to Arp2/3 complex, stimulates Arp2/3 nucleation activity to some degree in vitro, and exhibits genetic interactions with Arp2/3 complex and/or other NPFs. Las17/WASP and myosin I (with Vrp1) are categorized as class I NPFs because they bind actin monomers and have strong NPF effects (Sun et al. 2006). Pan1 and Abp1 are categorized as class II NPFs because they bind to F-actin and have comparably weak NPF effects (Figure 6C). Consistent with this classification, Arp2/3-inactivating mutations in Las17 combined with mutations in either myosin I or Vrp1 are synthetic lethal, demonstrating that class I NPF function is essential (Evangelista et al. 2000; Lechler et al. 2000). The roles of Pan1 and Abp1 in regulating Arp2/3 complex during endocytosis are less well understood (see below).


Actin and endocytosis in budding yeast.

Goode BL, Eskin JA, Wendland B - Genetics (2015)

Arp2/3 complex nucleation-promoting factors (NPFs). The figure depicts three proposed stages of NPF activity. (A) Inhibited NPFs. In earlier stages of patch development well before the arrival of Arp2/3 complex, the NPFs Las17/WASP and Pan1/Intersectin are maintained at patches in an inactive state by direct binding partners and are unable to recruit Arp2/3 complex. (B) Network priming. After subsequent deactivation of their inhibitors, Las17/WASP and Pan1/Intersectin are released to recruit and activate Arp2/3 complex. However, network nucleation also requires priming by one of two proposed mechanisms: (i) the capture or de novo assembly of an initial mother filament, which may depend on the Arp2/3-independent activities of Las17, Pan1, and/or Ysc84/Lsb4, or (ii) the stimulation of unbranched actin nucleation by Arp2/3 complex, as Nolen and colleagues have recently demonstrated can be induced by the S. pombe homolog of Ldb17/DIP/WISH (Wagner et al. 2013). (C) Active nucleation. After the priming stage, the Arp2/3 complex and its NPFs rapidly assemble a densely branched actin-filament network that promotes membrane remodeling. Class I NPFs bind G-actin: Las17/WASP, Vrp1/WIP, and myosin I. Class II NPFs bind F-actin: Pan1/Intersectin and Abp1. Some of the proteins are shown in complexes with their known binding partners. Additional interactions are indicated by dotted lines. Arrows represent stimulatory effects. Illustrations are based on available structural and sequence data. Abbreviations: THATCH, talin-HIP1/R/Sla2p actin-tethering C-terminal homology domain; ANTH, AP180 N-terminal homology domain; F-BAR, FER/Cip4 homology-Bin/Amphiphysin/Rvs domain; µHD, µ homology domain; EH, Eps15 homology domain; LRD, leucine-rich domain; CC, coiled coil; V, verprolin homology motif; C, connector motif; A, acidic motif; SH3, Src homology 3 domain; SHD, Sla1 homology domain; CTR, C-terminal repeats; ADF-H, actin depolymerizing factor homology domain; TH, tail homology domain; WBD, WASP-binding domain; EVH1, Ena/Vasp homology 1 domain; PP, polyproline region.
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fig6: Arp2/3 complex nucleation-promoting factors (NPFs). The figure depicts three proposed stages of NPF activity. (A) Inhibited NPFs. In earlier stages of patch development well before the arrival of Arp2/3 complex, the NPFs Las17/WASP and Pan1/Intersectin are maintained at patches in an inactive state by direct binding partners and are unable to recruit Arp2/3 complex. (B) Network priming. After subsequent deactivation of their inhibitors, Las17/WASP and Pan1/Intersectin are released to recruit and activate Arp2/3 complex. However, network nucleation also requires priming by one of two proposed mechanisms: (i) the capture or de novo assembly of an initial mother filament, which may depend on the Arp2/3-independent activities of Las17, Pan1, and/or Ysc84/Lsb4, or (ii) the stimulation of unbranched actin nucleation by Arp2/3 complex, as Nolen and colleagues have recently demonstrated can be induced by the S. pombe homolog of Ldb17/DIP/WISH (Wagner et al. 2013). (C) Active nucleation. After the priming stage, the Arp2/3 complex and its NPFs rapidly assemble a densely branched actin-filament network that promotes membrane remodeling. Class I NPFs bind G-actin: Las17/WASP, Vrp1/WIP, and myosin I. Class II NPFs bind F-actin: Pan1/Intersectin and Abp1. Some of the proteins are shown in complexes with their known binding partners. Additional interactions are indicated by dotted lines. Arrows represent stimulatory effects. Illustrations are based on available structural and sequence data. Abbreviations: THATCH, talin-HIP1/R/Sla2p actin-tethering C-terminal homology domain; ANTH, AP180 N-terminal homology domain; F-BAR, FER/Cip4 homology-Bin/Amphiphysin/Rvs domain; µHD, µ homology domain; EH, Eps15 homology domain; LRD, leucine-rich domain; CC, coiled coil; V, verprolin homology motif; C, connector motif; A, acidic motif; SH3, Src homology 3 domain; SHD, Sla1 homology domain; CTR, C-terminal repeats; ADF-H, actin depolymerizing factor homology domain; TH, tail homology domain; WBD, WASP-binding domain; EVH1, Ena/Vasp homology 1 domain; PP, polyproline region.
Mentions: NPFs directly associate with Arp2/3 complex and actin and serve as cofactors in stimulating nucleation. As mentioned above, there are four known NPFs in yeast: (1) Las17/WASP, (2) myosin I (Myo3 or Myo5) in a complex with Vrp1/WIP, (3) Pan1/Intersectin, and (4) Abp1 (Winter et al. 1999; Evangelista et al. 2000; Lechler et al. 2000; Duncan et al. 2001; Goode et al. 2001) (Figure 6). Each of these NPFs localizes to actin patches, binds to actin and to Arp2/3 complex, stimulates Arp2/3 nucleation activity to some degree in vitro, and exhibits genetic interactions with Arp2/3 complex and/or other NPFs. Las17/WASP and myosin I (with Vrp1) are categorized as class I NPFs because they bind actin monomers and have strong NPF effects (Sun et al. 2006). Pan1 and Abp1 are categorized as class II NPFs because they bind to F-actin and have comparably weak NPF effects (Figure 6C). Consistent with this classification, Arp2/3-inactivating mutations in Las17 combined with mutations in either myosin I or Vrp1 are synthetic lethal, demonstrating that class I NPF function is essential (Evangelista et al. 2000; Lechler et al. 2000). The roles of Pan1 and Abp1 in regulating Arp2/3 complex during endocytosis are less well understood (see below).

Bottom Line: Many critical aspects of the CME mechanism are conserved from yeast to mammals and were first elucidated in yeast, demonstrating that it is a powerful system for studying endocytosis.In this review, we describe our current mechanistic understanding of each step in the process of yeast CME, and the essential roles played by actin polymerization at these sites, while providing a historical perspective of how the landscape has changed since the preceding version of the YeastBook was published 17 years ago (1997).Finally, we discuss the key unresolved issues and where future studies might be headed.

View Article: PubMed Central - PubMed

Affiliation: Brandeis University, Department of Biology, Rosenstiel Center, Waltham, Massachusetts 02454 goode@brandeis.edu bwendland@jhu.edu.

Show MeSH
Related in: MedlinePlus