Kinesin-1-Mediated Capsid Disassembly and Disruption of the Nuclear Pore Complex Promote Virus Infection

Abstract

Many viruses deliver their genomes into the host cell nucleus for replication. However, the size restrictions of the nuclear pore complex (NPC), which regulates the passage of proteins, nucleic acids, and solutes through the nuclear envelope, require virus capsid uncoating before viral DNA can access the nucleus. We report a microtubule motor kinesin-1-mediated and NPC-supported mechanism of adenovirus uncoating. The capsid binds to the NPC filament protein Nup214 and kinesin-1 light-chain Klc1/2. The nucleoporin Nup358, which is bound to Nup214/Nup88, interacts with the kinesin-1 heavy-chain Kif5c to indirectly link the capsid to the kinesin motor. Kinesin-1 disrupts capsids docked at Nup214, which compromises the NPC and dislocates nucleoporins and capsid fragments into the cytoplasm. NPC disruption increases nuclear envelope permeability as indicated by the nuclear influx of large cytoplasmic dextran polymers. Thus, kinesin-1 uncoats viral DNA and compromises NPC integrity, allowing viral genomes nuclear access to promote infection.

The Role of Capsid Maturation on Adenovirus Priming for Sequential Uncoating

“…These energetic differences are likely related to the different infection mechanisms used by bacteriophage and adenovirus. dsDNA bacteriophage translocate their genomes into the host cell leaving the protein shell behind (58), whereas adenovirus is engulfed by the cell and disassembles within to expose its genome to the cell nucleus machinery (59). In this sense, adenovirus is similar to other nonenveloped animal viruses, such as poliovirus, where interaction with the receptor is the trigger to start the cascade of structural changes leading to uncoating (60).…”

Uncoating of non-enveloped viruses

“…Recent imaging and tracking experiments with adenoviruses have shown that motors not only overcome diffusion barriers, but are key for virus uncoating as well [47,48].…”

“…Virus docks at the cytoplasmic side of the nuclear pore complex (NPC) by binding to the nucleoporin Nup214, and undergoes final disassembly [58,73]. This step is mediated by the microtubule motor kinesin-1 [48]. The virus recruits the light chain of the kinesin motor through its minor capsid-associated protein IX.…”

“…Strunze et al [48] suggested that kinesin is pulling on the virus capsid against a holding force from the NPC, and thereby disrupts the capsid. This disruption process also dislodges Nup214, Nup358 and Nup62 from the NPC, and transiently increases the permeability of the NPCs for influx of solutes.…”

Fluorescence Tracking of Genome Release during Mechanical Unpacking of Single Viruses

“…[5][6][7] Conformational transitions in the capsid can be triggered by cellular cues, such as receptor binding, the ionic environment, or mechanical cues. [8][9][10][11] Whether the released cargo carries out its designated function depends not only on its protection by the capsid but, in many cases, also requires a maturation step to render the cargo active. [12][13][14][15] Thus, a better understanding of the mechanisms that both viruses and artificial nanoparticles employ for cargo delivery, demands an integrated approach involving structural dynamics of the capsid, and the physical state of the cargo.…”