Phafin2 modulates the structure and function of endosomes by a Rab5-dependent mechanism

Lin, Wen Jie; Yang, Chung‐May; Lin, Ying; Tsai, Meng Chun; Yang, Cheng; Tung, Chien Yi; Ho, Pei Yun; Kao, Fu Jen; Lin, Chi

doi:10.1016/j.bbrc.2009.12.016

Cited by 17 publications

(44 citation statements)

References 28 publications

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“…Since rush mutants are homozygous viable and endosomal markers are normal in rush mutant cells, Rush may function redundantly with other factors in this process. Phafin2, the human homologue of Rush, has been shown to increase the binding of Rab5 to its effectors as monitored by a fluorescence resonance energy transfer (FRET) assay with the Rab5-binding domain of Rabaptin5 (Lin et al ., 2010). Dominant-negative Rab5 disrupted formation of Phafin2-induced large endosomes, positioning Rab5 activity upstream of Phafin2 (Lin et al ., 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Most FYVE domain–containing proteins localize to endosomes (Gillooly et al ., 2001), suggesting that Rush might be involved in endocytosis. Rush has two human homologues, Phafin1 and Phafin2, which have been described as regulating Rab5-mediated endocytosis (Lin et al ., 2010) and participating in tumor necrosis factor (TNF)-dependent apoptosis (Chen et al ., 2005; Li et al ., 2008; Lin et al ., 2010). Interestingly, Phafin2 is overexpressed in several cancer types, including human hepatocellular carcinoma and breast cancer (Chen et al ., 2002; Weisz et al ., 2004; Lin et al ., 2010).…”

Section: Introductionmentioning

confidence: 99%

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The phosphoinositide-associated protein Rush hour regulates endosomal trafficking inDrosophila

Gailite

Egger-Adam

Wodarz

2012

MBoC

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The FYVE-domain protein Rush hour (Rush) binds directly to phosphatidylinositol 3-phosphate and to guanosine diphosphate dissociation inhibitor. It colocalizes with Rab7 and Hrs, and a rush null mutation interacts genetically with mutations in Rab5, Gdi, hrs, and carnation, the fly Vps33 homologue. Rush overexpression blocks the transition from late endosomes to lysosomes, pointing to a function for Rush in regulation of Rabs.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The phosphoinositide-associated protein Rush hour regulates endosomal trafficking inDrosophila

Gailite

Egger-Adam

Wodarz

2012

MBoC

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“…2 PtdIns(3)P is a hallmark of endosomes as it mediates the recruitment of effector proteins to these compartments; thus, both PtdIns(3)P-interacting domains can target Phafin2 to PtdIns(3)P-enriched membranes. Phafin2 regulates the function and structure of endosomes through a Rab5-dependent process 3 although no direct interaction of Phafin2 and Rab5 occurs. 4 Several lines of evidence suggest that Phafin2, the Phafin family member protein Phafin1, and the Drosophila homologue Rush promote the enlargement of early endosomes [3][4][5][6] with their FYVE domains playing a dominant role.…”

Section: Introductionmentioning

confidence: 99%

“…Phafin2 regulates the function and structure of endosomes through a Rab5-dependent process 3 although no direct interaction of Phafin2 and Rab5 occurs. 4 Several lines of evidence suggest that Phafin2, the Phafin family member protein Phafin1, and the Drosophila homologue Rush promote the enlargement of early endosomes [3][4][5][6] with their FYVE domains playing a dominant role. 3 Phafin2 interacts with the FYVE domain-containing protein EEA1, which regulates endosomal cargo trafficking and fusion events, but does not directly participate in cargo sorting.…”

Section: Introductionmentioning

confidence: 99%

“…4 Several lines of evidence suggest that Phafin2, the Phafin family member protein Phafin1, and the Drosophila homologue Rush promote the enlargement of early endosomes [3][4][5][6] with their FYVE domains playing a dominant role. 3 Phafin2 interacts with the FYVE domain-containing protein EEA1, which regulates endosomal cargo trafficking and fusion events, but does not directly participate in cargo sorting. 4 A role for lysosomal Phafin2 in the induction of autophagy has also been recently reported.…”

Section: Introductionmentioning

confidence: 99%

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Structural, Thermodynamic and Phosphatidylinositol 3-Phosphate Binding Properties of Phafin2

Tang

2017

Biophysical Journal

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Phafin2 is a phosphatidylinositol 3-phosphate (PtdIns(3)P) binding protein involved in the regulation of endosomal cargo trafficking and lysosomal induction of autophagy. Binding of Phafin2 to PtdIns(3)P is mediated by both its PH and FYVE domains. However, there are no studies on the structural basis, conformational stability, and lipid interactions of Phafin2 to better understand how this protein participates in signaling at the surface of endomembrane compartments. Here, we show that human Phafin2 is a moderately elongated monomer of~28 kDa with an intensityaverage hydrodynamic diameter of~7 nm. Circular dichroism (CD) analysis indicates that Phafin2 exhibits an a/b structure and predicts~40% random coil content in the protein. Heteronuclear NMR data indicates that a unique conformation of Phafin2 is present in solution and dispersion of resonances suggests that the protein exhibits random coiled regions, in agreement with the CD data. Phafin2 is stable, displaying a melting temperature of 48.48C. The folding-unfolding curves, obtained using urea-and guanidine hydrochloride-mediated denaturation, indicate that Phafin2 undergoes a two-state native-to-denatured transition. Analysis of these transitions shows that the free energy change for urea-and guanidine hydrochloride-induced Phafin2 denaturation in water is 4 kcal mol 21 . PtdIns(3)P binding to Phafin2 occurs with high affinity, triggering minor conformational changes in the protein. Taken together, these studies represent a platform for establishing the structural basis of Phafin2 molecular interactions and the role of the two potentially redundant PtdIns(3)P-binding domains of the protein in endomembrane compartments.

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Structural, thermodynamic, and phosphatidylinositol 3‐phosphate binding properties of Phafin2

Tang

Deng

et al. 2017

Protein Science

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Phafin2 is a phosphatidylinositol 3‐phosphate (PtdIns(3)P) binding protein involved in the regulation of endosomal cargo trafficking and lysosomal induction of autophagy. Binding of Phafin2 to PtdIns(3)P is mediated by both its PH and FYVE domains. However, there are no studies on the structural basis, conformational stability, and lipid interactions of Phafin2 to better understand how this protein participates in signaling at the surface of endomembrane compartments. Here, we show that human Phafin2 is a moderately elongated monomer of ∼28 kDa with an intensity‐average hydrodynamic diameter of ∼7 nm. Circular dichroism (CD) analysis indicates that Phafin2 exhibits an α/β structure and predicts ∼40% random coil content in the protein. Heteronuclear NMR data indicates that a unique conformation of Phafin2 is present in solution and dispersion of resonances suggests that the protein exhibits random coiled regions, in agreement with the CD data. Phafin2 is stable, displaying a melting temperature of 48.4°C. The folding‐unfolding curves, obtained using urea‐ and guanidine hydrochloride‐mediated denaturation, indicate that Phafin2 undergoes a two‐state native‐to‐denatured transition. Analysis of these transitions shows that the free energy change for urea‐ and guanidine hydrochloride‐induced Phafin2 denaturation in water is ∼4 kcal mol−1. PtdIns(3)P binding to Phafin2 occurs with high affinity, triggering minor conformational changes in the protein. Taken together, these studies represent a platform for establishing the structural basis of Phafin2 molecular interactions and the role of the two potentially redundant PtdIns(3)P‐binding domains of the protein in endomembrane compartments.

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Phafin2 modulates the structure and function of endosomes by a Rab5-dependent mechanism

Cited by 17 publications

References 28 publications

The phosphoinositide-associated protein Rush hour regulates endosomal trafficking inDrosophila

The phosphoinositide-associated protein Rush hour regulates endosomal trafficking inDrosophila

Structural, Thermodynamic and Phosphatidylinositol 3-Phosphate Binding Properties of Phafin2

Structural, thermodynamic, and phosphatidylinositol 3‐phosphate binding properties of Phafin2

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