Recognition of the F&H motif by the Lowe Syndrome protein OCRL

Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut, USA.
Nature Structural & Molecular Biology (Impact Factor: 13.31). 06/2011; 18(7):789-95. DOI: 10.1038/nsmb.2071
Source: PubMed


Lowe syndrome and type 2 Dent disease are caused by defects in the inositol 5-phosphatase OCRL. Most missense mutations in the OCRL ASH-RhoGAP domain that are found in affected individuals abolish interactions with the endocytic adaptors APPL1 and Ses (both Ses1 and Ses2), which bind OCRL through a short phenylalanine and histidine (F&H) motif. Using X-ray crystallography, we have identified the F&H motif binding site on the RhoGAP domain of OCRL. Missense mutations associated with disease affected F&H binding indirectly by destabilizing the RhoGAP fold. By contrast, a disease-associated mutation that does not perturb F&H binding and ASH-RhoGAP stability disrupted the interaction of OCRL with Rab5. The F&H binding site of OCRL is conserved even in species that do not have an identified homolog for APPL or Ses. Our study predicts the existence of other OCRL binding partners and shows that the perturbation of OCRL interactions has a crucial role in disease.

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Available from: Laura Swan
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    • "Half of the mutations affect enzyme activity directly; the others are distant from the active site and exert indirect effects. In addition to the OCRL protein mutation at the Rab5 binding site, Lowe syndrome and type 2 Dent disease-associated missense mutations affect the short phenylalanine and histidine motif indirectly by destabilizing the RhoGAP fold (Pirruccello et al., 2011). In the NNS syndrome, the G201V substitution caused conformational changes not only in Thr73 and Lys105 at the catalytic site; additional conformational changes were observed in the S8–H3 loop located at the interface between b4 and b5i, which impaired the assembly of the 20S proteasome (Arima et al., 2011). "
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    • "OCRL is a multidomain protein with a split N-terminal pleckstrin-homology (PH) domain (Mao et al, 2009), a central 5-phosphatase catalytic domain (Tsujishita et al, 2001; Schmid et al, 2004), an ASPM-SPD-2-Hydin (ASH) domain (Ponting, 2006; Erdmann et al, 2007; McCrea et al, 2008), a C-terminal inactive Rho-GTPase-activating protein (GAP) domain (Faucherre et al, 2003), and multiple clathrin-binding motifs (Choudhury et al, 2005, 2009) and Rab-binding regions (Hyvola et al, 2006). Through these domains and motifs, OCRL interacts with key components of the membrane-trafficking machineries, such as clathrin, the clathrin adaptor AP2, small GTPases (like Rab5, Rab6, Rab14, and Arf6), endocytic adaptors (like APPL1), and the recently identified Ses proteins (Ungewickell et al, 2004; Choudhury et al, 2005, 2009; Hyvola et al, 2006; Lichter-Konecki et al, 2006; Erdmann et al, 2007; Fukuda et al, 2008; McCrea et al, 2008; Swan et al, 2010; Noakes et al, 2011; Pirruccello et al, 2011). "
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    ABSTRACT: Mutations in the phosphatidylinositol 4,5-bisphosphate (PtdIns4,5P(2)) 5-phosphatase OCRL cause Lowe syndrome, which is characterised by congenital cataracts, central hypotonia, and renal proximal tubular dysfunction. Previous studies have shown that OCRL interacts with components of the endosomal machinery; however, its role in endocytosis, and thus the pathogenic mechanisms of Lowe syndrome, have remained elusive. Here, we show that via its 5-phosphatase activity, OCRL controls early endosome (EE) function. OCRL depletion impairs the recycling of multiple classes of receptors, including megalin (which mediates protein reabsorption in the kidney) that are retained in engorged EEs. These trafficking defects are caused by ectopic accumulation of PtdIns4,5P(2) in EEs, which in turn induces an N-WASP-dependent increase in endosomal F-actin. Our data provide a molecular explanation for renal proximal tubular dysfunction in Lowe syndrome and highlight that tight control of PtdIns4,5P(2) and F-actin at the EEs is essential for exporting cargoes that transit this compartment.
    Full-text · Article · Dec 2011 · The EMBO Journal
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    • "Junctional targeting by OCRL1 required both ASH and RhoGAP domains in tandem, the same requirement as for the interaction of OCRL1 with APPL1 and the recently described endocytic proteins IPIP27A/B (also called Ses1/2), which all share an OCRL1-interacting “F&H” motif [20], [21]. It is possible that the interaction partner of OCRL1 at junctions contains a F&H-like sequence [39]. "
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