Ist1 Regulates Vps4 Localization and Assembly

Dimaano, Christian; Jones, Charles B.; Hanono, Abraham; Curtiss, Matt; Babst, Markus

doi:10.1091/mbc.e07-08-0747

Cited by 124 publications

(222 citation statements)

References 28 publications

(43 reference statements)

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“…Interestingly, ␣5 occupies an exposed position in the crystal structure of CHMP3 (Muziol et al, 2006), which probably represents the "open" form of these proteins . We propose that interaction of VPS4 -using its MIT domain, elements within its AAAϩ domain such as the "pore loops" known to be important for its function (Scott et al, 2005a), or possibly an associated cofactor such as the recently described Ist1 (Dimaano et al, 2008)-with ␣5 in all ESCRT-III proteins is likely to be an important additional step in ESCRT-III complex disassembly.…”

Section: Discussionmentioning

confidence: 98%

“…We conclude that conserved acidic residues at the center of ␣5 are an important component of the secondary VPS4 binding site. Because these experiments were carried out in cells that highly overexpress VPS4B and the ESCRT-III protein in question, we consider it unlikely but cannot exclude that an intermediate protein such as Ist1 (Dimaano et al, 2008) mediates this secondary interaction between VPS4 and the acidic ␣5 residues in ESCRT-III proteins.…”

Section: A Second Binding Site For Vps4 In Escrt-iii Proteinsmentioning

confidence: 99%

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Novel Interactions of ESCRT-III with LIP5 and VPS4 and their Implications for ESCRT-III Disassembly

Shim

Merrill

Hanson

2008

MBoC

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The AAA؉ ATPase VPS4 plays an essential role in multivesicular body biogenesis and is thought to act by disassembling ESCRT-III complexes. VPS4 oligomerization and ATPase activity are promoted by binding to LIP5. LIP5 also binds to the ESCRT-III like protein CHMP5/hVps60, but how this affects its function remains unclear. Here we confirm that LIP5 binds tightly to CHMP5, but also find that it binds well to additional ESCRT-III proteins including CHMP1B, CHMP2A/ hVps2-1, and CHMP3/hVps24 but not CHMP4A/hSnf7-1 or CHMP6/hVps20. LIP5 binds to a different region within CHMP5 than within the other ESCRT-III proteins. In CHMP1B and CHMP2A, its binding site encompasses sequences at the proteins' extreme C-termini that overlap with "MIT interacting motifs" (MIMs) known to bind to VPS4. We find unexpected evidence of a second conserved binding site for VPS4 in CHMP2A and CHMP1B, suggesting that LIP5 and VPS4 may bind simultaneously to these proteins despite the overlap in their primary binding sites. Finally, LIP5 binds preferentially to soluble CHMP5 but instead to polymerized CHMP2A, suggesting that the newly defined interactions between LIP5 and ESCRT-III proteins may be regulated by ESCRT-III conformation. These studies point to a role for direct binding between LIP5 and ESCRT-III proteins that is likely to complement LIP5's previously described ability to regulate VPS4 activity.

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Section: Discussionmentioning

confidence: 98%

Section: A Second Binding Site For Vps4 In Escrt-iii Proteinsmentioning

confidence: 99%

Novel Interactions of ESCRT-III with LIP5 and VPS4 and their Implications for ESCRT-III Disassembly

Shim

Merrill

Hanson

2008

MBoC

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“…Although the Ist1 carboxyl terminus stimulates Vps4 ATPase activity, full-length Ist1 inhibits Vps4 ATPase activity (57). However, an Ist1 mutant defective for Did2 MIM1 binding (L168A,Y172A) (26) stimulates Vps4 in a manner dependent on both the Ist1 MIM1 and the Vps4 MIT domain (Fig.…”

Section: Residues Within the Vps4 Small Atpase Domain Mediatementioning

confidence: 99%

Vps4 Stimulatory Element of the Cofactor Vta1 Contacts the ATPase Vps4 α7 and α9 to Stimulate ATP Hydrolysis

Davies

Norgan

Payne

et al. 2014

Journal of Biological Chemistry

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Background: ESCRT-III can enhance Vta1 stimulation of Vps4 ATPase activity via the Vps4 stimulatory element (VSE) of Vta1. Results: ␣7 and ␣9 of the Vps4 small AAA domain mediate VSE stimulation, contributing to Vps4 function in vivo. Conclusion: Vta1 contacts Vps4 ␣7 and ␣9 during ESCRT-III-enhanced stimulation of Vps4. Significance: These studies identify a novel mechanism of Vps4 stimulation.

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“…an ESCRT-III domain, Ist1/IST1 (Dimaano et al 2008;Rue et al 2008;Bajorek et al 2009) and CHMP7 (Horii et al 2006).…”

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Evidence for a Nonendosomal Function of the Saccharomyces cerevisiae ESCRT-III-Like Protein Chm7

et al. 2015

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Endosomal sorting complex required for transport (ESCRT) proteins are involved in a number of cellular processes, such as endosomal protein sorting, HIV budding, cytokinesis, plasma membrane repair, and resealing of the nuclear envelope during mitosis. Here we explored the function of a noncanonical member of the ESCRT-III protein family, the Saccharomyces cerevisiae ortholog of human CHMP7. Very little is known about this protein. In silico analysis predicted that Chm7 (yeast ORF YJL049w) is a fusion of an ESCRT-II and ESCRT-III-like domain, which would suggest a role in endosomal protein sorting. However, our data argue against a role of Chm7 in endosomal protein sorting. The turnover of the endocytic cargo protein Ste6 and the vacuolar protein sorting of carboxypeptidase S (CPS) were not affected by CHM7 deletion, and Chm7 also responded very differently to a loss in Vps4 function compared to a canonical ESCRT-III protein. Our data indicate that the Chm7 function could be connected to the endoplasmic reticulum (ER). In line with a function at the ER, we observed a strong negative genetic interaction between the deletion of a gene function (APQ12) implicated in nuclear pore complex assembly and messenger RNA (mRNA) export and the CHM7 deletion. The patterns of genetic interactions between the APQ12 deletion and deletions of ESCRT-III genes, two-hybrid interactions, and the specific localization of mCherry fusion proteins are consistent with the notion that Chm7 performs a novel function at the ER as part of an alternative ESCRT-III complex.

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Ist1 Regulates Vps4 Localization and Assembly

Cited by 124 publications

References 28 publications

Novel Interactions of ESCRT-III with LIP5 and VPS4 and their Implications for ESCRT-III Disassembly

Novel Interactions of ESCRT-III with LIP5 and VPS4 and their Implications for ESCRT-III Disassembly

Vps4 Stimulatory Element of the Cofactor Vta1 Contacts the ATPase Vps4 α7 and α9 to Stimulate ATP Hydrolysis

Evidence for a Nonendosomal Function of the Saccharomyces cerevisiae ESCRT-III-Like Protein Chm7

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