Edible Mushroom (Agaricus bisporus) Lectin, Which Reversibly Inhibits Epithelial Cell Proliferation, Blocks Nuclear Localization Sequence-dependent Nuclear Protein Import

Members of the interferon-induced class of nuclear factors possess a putative CcN motif, comparable with that within proteins such as the simian virus 40 large tumour antigen (T-ag), which confers phosphorylation-mediated regulation of nuclear-localization sequence (NLS)-dependent nuclear import. Here we examine the functionality of the interferon-induced factor 16 (IFI 16) CcN motif, demonstrating its ability to target a heterologous protein to the nucleus, and to be phosphorylated specifically by the CcN-motif-phosphorylating protein kinase CK2 (CK2). The IFI 16 NLS, however, has novel properties, conferring ATP-dependent nuclear import completely independent of cytosolic factors, as well as binding to nuclear components. The IFI 16 NLS is not recognized with high affinity by the NLS-binding importin heterodimer, and transport mediated by it is insensitive to non-hydrolysable GTP analogues. The IFI 16 NLS thus mediates nuclear import through a pathway completely distinct from that of conventional NLSs, such as that of T-ag, but intriguingly resembling that of the NLS of the HIV-1 transactivator protein Tat. Since the IFI 16 CK2 site enhances nuclear import through facilitating binding to nuclear components, this represents a novel mechanism by which the site regulates nuclear-protein import, and constitutes a difference between the IFI 16 and Tat NLSs that may be of importance in the immune response.

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An N-terminal truncated form of Orp150 is a cytoplasmic ligand for the anti-proliferative edible mushroom Agaricus bisporus lectin and is required for NLS-dependent nuclear protein import

Biochemical Society Transactions ◽

10.1042/bst030a030 ◽

2002 ◽

Vol 30 (1) ◽

pp. A30-A30

Author(s):

LG Yu ◽

N Andrews ◽

M Weldon ◽

OV Gerasimenko ◽

BJ Campbel ◽

...

Keyword(s):

Agaricus Bisporus ◽

Protein Import ◽

Nuclear Protein ◽

Edible Mushroom ◽

Truncated Form ◽

Nuclear Protein Import

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Functional domains in nuclear import factor p97 for binding the nuclear localization sequence receptor and the nuclear pore.

Molecular Biology of the Cell ◽

10.1091/mbc.8.6.945 ◽

1997 ◽

Vol 8 (6) ◽

pp. 945-956 ◽

Cited By ~ 55

Author(s):

N C Chi ◽

S A Adam

Keyword(s):

Nuclear Localization ◽

Receptor Binding ◽

Protein Import ◽

Binding Domain ◽

Nuclear Localization Sequence ◽

Functional Domains ◽

Nuclear Pore ◽

Binding Domains ◽

Localization Sequence ◽

Ran Gtp

The interaction of the nuclear protein import factor p97 with the nuclear localization sequence (NLS) receptor, the nuclear pore complex, and Ran/TC4 is important for coordinating the events of protein import to the nucleus. We have mapped the binding domains on p97 for the NLS receptor and the nuclear pore. The NLS receptor-binding domain of p97 maps to the C-terminal 60% of the protein between residues 356 and 876. The pore complex-binding domain of p97 maps to residues 152-352. The pore complex-binding domain overlaps the Ran-GTP- and Ran-GDP-binding domains on p97, but only Ran-GTP competes for docking in permeabilized cells. The N-ethylmaleimide sensitivity of the p97 for docking was investigated and found to be due to inhibition of p97 binding to the pore complex and to the NLS receptor. Site-directed mutagenesis of conserved cysteine residues in the pore- and receptor-binding domains identified two cysteines, C223 and C228, that were required for p97 to bind the nuclear pore. Inhibition studies on docking and accumulation of a NLS protein provided additional evidence that the domains identified biochemically are the functional domains involved in protein import. Together, these results suggest that Ran-GTP dissociates the receptor complex and prevents p97 binding to the pore by inducing a conformational change in the structure of p97 rather than simple competition for binding sites.

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Edible mushroom (Agaricus bisporus) lectin inhibits human retinal pigment epithelial cell proliferation in vitro

Wound Repair and Regeneration ◽

10.1046/j.1524-475x.2003.11408.x ◽

2003 ◽

Vol 11 (4) ◽

pp. 285-291 ◽

Cited By ~ 14

Author(s):

David Kent ◽

Carl M. Sheridan ◽

Heather A. Tomkinson ◽

Sarah J. White ◽

Paul Hiscott ◽

...

Keyword(s):

Cell Proliferation ◽

Agaricus Bisporus ◽

Retinal Pigment Epithelial ◽

Retinal Pigment Epithelial Cell ◽

Retinal Pigment ◽

Edible Mushroom ◽

Epithelial Cell Proliferation ◽

Pigment Epithelial ◽

Proliferation In Vitro

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The Paralogue of the Intrinsically Disordered Nuclear Protein 1 Has a Nuclear Localization Sequence that Binds to Human Importin α3

International Journal of Molecular Sciences ◽

10.3390/ijms21197428 ◽

2020 ◽

Vol 21 (19) ◽

pp. 7428

Author(s):

José L. Neira ◽

Bruno Rizzuti ◽

Ana Jiménez-Alesanco ◽

Olga Abián ◽

Adrián Velázquez-Campoy ◽

...

Keyword(s):

Nuclear Localization ◽

Protein Transport ◽

Nuclear Protein ◽

Nuclear Translocation ◽

Intrinsically Disordered Protein ◽

Titration Calorimetry ◽

Nuclear Localization Sequence ◽

Intrinsically Disordered ◽

Localization Sequence ◽

High Flexibility

Numerous carrier proteins intervene in protein transport from the cytoplasm to the nucleus in eukaryotic cells. One of those is importin α, with several human isoforms; among them, importin α3 (Impα3) features a particularly high flexibility. The protein NUPR1L is an intrinsically disordered protein (IDP), evolved as a paralogue of nuclear protein 1 (NUPR1), which is involved in chromatin remodeling and DNA repair. It is predicted that NUPR1L has a nuclear localization sequence (NLS) from residues Arg51 to Gln74, in order to allow for nuclear translocation. We studied in this work the ability of intact NUPR1L to bind Impα3 and its depleted species, ∆Impα3, without the importin binding domain (IBB), using fluorescence, isothermal titration calorimetry (ITC), circular dichroism (CD), nuclear magnetic resonance (NMR), and molecular docking techniques. Furthermore, the binding of the peptide matching the isolated NLS region of NUPR1L (NLS-NUPR1L) was also studied using the same methods. Our results show that NUPR1L was bound to Imp α3 with a low micromolar affinity (~5 μM). Furthermore, a similar affinity value was observed for the binding of NLS-NUPR1L. These findings indicate that the NLS region, which was unfolded in isolation in solution, was essentially responsible for the binding of NUPR1L to both importin species. This result was also confirmed by our in silico modeling. The binding reaction of NLS-NUPR1L to ∆Impα3 showed a larger affinity (i.e., lower dissociation constant) compared with that of Impα3, confirming that the IBB could act as an auto-inhibition region of Impα3. Taken together, our findings pinpoint the theoretical predictions of the NLS region in NUPR1L and, more importantly, suggest that this IDP relies on an importin for its nuclear translocation.

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