Clathrin-mediated endocytosis (CME) is the main mechanism by which mammalian cells control their cell surface proteome. Proper operation of the pivotal CME cargo adaptor AP2 requires membrane-localized Fer/Cip4 homology domain-only proteins (FCHO). Here, live-cell enhanced total internal reflection fluorescence-structured illumination microscopy shows that FCHO marks sites of clathrin-coated pit (CCP) initiation, which mature into uniform-sized CCPs comprising a central patch of AP2 and clathrin corralled by an FCHO/Epidermal growth factor potential receptor substrate number 15 (Eps15) ring. We dissect the network of interactions between the FCHO interdomain linker and AP2, which concentrates, orients, tethers, and partially destabilizes closed AP2 at the plasma membrane. AP2's subsequent membrane deposition drives its opening, which triggers FCHO displacement through steric competition with phosphatidylinositol 4,5-bisphosphate, clathrin, cargo, and CME accessory factors. FCHO can now relocate toward a CCP's outer edge to engage and activate further AP2s to drive CCP growth/maturation.

• Publikační typ
• časopisecké články MeSH

The assembly of a hexameric lattice of retroviral immature particles requires the involvement of cell factors such as proteins and small molecules. A small, negatively charged polyanionic molecule, myo-inositol hexaphosphate (IP6), was identified to stimulate the assembly of immature particles of HIV-1 and other lentiviruses. Interestingly, cryo-electron tomography analysis of the immature particles of two lentiviruses, HIV-1 and equine infectious anemia virus (EIAV), revealed that the IP6 binding site is similar. Based on this amino acid conservation of the IP6 interacting site, it is presumed that the assembly of immature particles of all lentiviruses is stimulated by IP6. Although this specific region for IP6 binding may be unique for lentiviruses, it is plausible that other retroviral species also recruit some small polyanion to facilitate the assembly of their immature particles. To study whether the assembly of retroviruses other than lentiviruses can be stimulated by polyanionic molecules, we measured the effect of various polyanions on the assembly of immature virus-like particles of Rous sarcoma virus (RSV), a member of alpharetroviruses, Mason-Pfizer monkey virus (M-PMV) representative of betaretroviruses, and murine leukemia virus (MLV), a member of gammaretroviruses. RSV, M-PMV and MLV immature virus-like particles were assembled in vitro from truncated Gag molecules and the effect of selected polyanions, myo-inostol hexaphosphate, myo-inositol, glucose-1,6-bisphosphate, myo-inositol hexasulphate, and mellitic acid, on the particles assembly was quantified. Our results suggest that the assembly of immature particles of RSV and MLV was indeed stimulated by the presence of myo-inostol hexaphosphate and myo-inositol, respectively. In contrast, no effect on the assembly of M-PMV as a betaretrovirus member was observed.

• Klíčová slova
• CAH *, IP6 *, M-PMV *, MLV *, RSV *, SP domain *, assembly *, hexamer *, immature *, polyanion *,
• MeSH
• Alpharetrovirus fyziologie   MeSH
• Betaretrovirus fyziologie   MeSH
• buněčná membrána chemie   metabolismus   MeSH
• Gammaretrovirus fyziologie   MeSH
• genové produkty gag chemie   metabolismus   MeSH
• interakce hostitele a patogenu * MeSH
• kultivované buňky MeSH
• polyelektrolyty chemie   metabolismus   MeSH
• Retroviridae fyziologie   ultrastruktura   MeSH
• sestavení viru * MeSH
• virion MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• genové produkty gag MeSH
• polyanions MeSH Prohlížeč
• polyelektrolyty MeSH

Proper assembly and disassembly of both immature and mature HIV-1 hexameric lattices are critical for successful viral replication. These processes are facilitated by several host-cell factors, one of which is myo-inositol hexaphosphate (IP6). IP6 participates in the proper assembly of Gag into immature hexameric lattices and is incorporated into HIV-1 particles. Following maturation, IP6 is also likely to participate in stabilizing capsid protein-mediated mature hexameric lattices. Although a structural-functional analysis of the importance of IP6 in the HIV-1 life cycle has been reported, the effect of IP6 has not yet been quantified. Using two in vitro methods, we quantified the effect of IP6 on the assembly of immature-like HIV-1 particles, as well as its stabilizing effect during disassembly of mature-like particles connected with uncoating. We analyzed a broad range of molar ratios of protein hexamers to IP6 molecules during assembly and disassembly. The specificity of the IP6-facilitated effect on HIV-1 particle assembly and stability was verified by K290A, K359A, and R18A mutants. In addition to IP6, we also tested other polyanions as potential assembly cofactors or stabilizers of viral particles.IMPORTANCE Various host cell factors facilitate critical steps in the HIV-1 replication cycle. One of these factors is myo-inositol hexaphosphate (IP6), which contributes to assembly of HIV-1 immature particles and helps maintain the well-balanced metastability of the core in the mature infectious virus. Using a combination of two in vitro methods to monitor assembly of immature HIV-1 particles and disassembly of the mature core-like structure, we quantified the contribution of IP6 and other small polyanion molecules to these essential steps in the viral life cycle. Our data showed that IP6 contributes substantially to increasing the assembly of HIV-1 immature particles. Additionally, our analysis confirmed the important role of two HIV-1 capsid lysine residues involved in interactions with IP6. We found that myo-inositol hexasulphate also stabilized the HIV-1 mature particles in a concentration-dependent manner, indicating that targeting this group of small molecules may have therapeutic potential.

• Klíčová slova
• HIV-1, IP6, assembly, capsid, immature, mature, polyanion,
• MeSH
• genové produkty gag - virus lidské imunodeficience chemie   genetika   metabolismus   MeSH
• HIV-1 chemie   genetika   MeSH
• missense mutace MeSH
• polyelektrolyty MeSH
• polymery chemie   MeSH
• sestavení viru * MeSH
• substituce aminokyselin MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• genové produkty gag - virus lidské imunodeficience MeSH
• polyanions MeSH Prohlížeč
• polyelektrolyty MeSH
• polymery MeSH

A major structural retroviral protein, capsid protein (CA), is able to oligomerize into two different hexameric lattices, which makes this protein a key component for both the early and late stages of HIV-1 replication. During the late stage, the CA protein, as part of the Gag polyprotein precursor, facilitates protein-protein interactions that lead to the assembly of immature particles. Following protease activation and Gag polyprotein processing, CA also drives the assembly of the mature viral core. In the early stage of infection, the role of the CA protein is distinct. It controls the disassembly of the mature CA hexameric lattice i.e., uncoating, which is critical for the reverse transcription of the single-stranded RNA genome into double stranded DNA. These properties make CA a very attractive target for small molecule functioning as inhibitors of HIV-1 particle assembly and/or disassembly. Of these, inhibitors containing the PF74 scaffold have been extensively studied. In this study, we reported a series of modifications of the PF74 molecule and its characterization through a combination of biochemical and structural approaches. Our data supported the hypothesis that PF74 stabilizes the mature HIV-1 CA hexameric lattice. We identified derivatives with a higher in vitro stabilization activity in comparison to the original PF74 molecule.

• Klíčová slova
• HIV-1 CA inhibitor, PF74 derivatives, disassembly, uncoating,
• MeSH
• HIV-1 účinky léků   MeSH
• indoly chemická syntéza   chemie   farmakologie   MeSH
• látky proti HIV chemická syntéza   chemie   farmakologie   MeSH
• lidé MeSH
• magnetická rezonanční spektroskopie MeSH
• molekulární konformace MeSH
• molekulární modely MeSH
• molekulární struktura MeSH
• racionální návrh léčiv MeSH
• rekombinantní proteiny MeSH
• sestavení viru účinky léků   MeSH
• techniky syntetické chemie MeSH
• virion účinky léků   ultrastruktura   MeSH
• virové plášťové proteiny antagonisté a inhibitory   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• indoly MeSH
• látky proti HIV MeSH
• rekombinantní proteiny MeSH
• virové plášťové proteiny MeSH