title: Hop-on hop-off: importin-α-guided tours to the nucleus in innate immune signaling.
abstract: Nuclear translocation of immune regulatory proteins and signal transducers is an essential process in animal and plant defense signaling against pathogenic microbes. Import of proteins containing a nuclear localization signal (NLS) into the nucleus is mediated by nuclear transport receptors termed importins, typically dimers of a cargo-binding α-subunit and a β-subunit that mediates translocation through the nuclear pore complex. Here, we review recent reports of importin-α cargo specificity and mutant phenotypes in plant- and animal-microbe interactions. Using homology modeling of the NLS-binding cleft of nine predicted Arabidopsis α-importins and analyses of their gene expression patterns, we discuss functional redundancy and specialization within this transport receptor family. In addition, we consider how pathogen effector proteins that promote infection by manipulating host cell nuclear processes might compete with endogenous cargo proteins for nuclear uptake.
authors.affiliation: Department of Biological Chemistry, John Innes Centre, Norwich Research Park Norwich, UK.
authors.forename: Lennart
authors.initials: L
authors.lastname: Wirthmueller
authors.forename: Charlotte
authors.initials: C
authors.lastname: Roth
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Banfield
authors.forename: Marcel
authors.initials: M
authors.lastname: Wiermer
keywords: Arabidopsis; importin-α; innate immunity; nuclear protein import; nucleocytoplasmic transport