title: Structural and functional analysis of Hikeshi, a new nuclear transport receptor of Hsp70s.
abstract: Hikeshi is a nuclear transport receptor required for cell survival after stress. It mediates heat-shock-induced nuclear import of 70 kDa heat-shock proteins (Hsp70s) through interactions with FG-nucleoporins (FG-Nups), which are proteins in nuclear pore complexes (NPCs). Here, the crystal structure of human Hikeshi is presented at 1.8 Å resolution. Hikeshi forms an asymmetric homodimer that is responsible for the interaction with Hsp70s. The asymmetry of Hikeshi arises from the distinct conformation of the C-terminal domain (CTD) and the flexibility of the linker regions of each monomer. Structure-guided mutational analyses showed that both the flexible linker region and the CTD are important for nuclear import of Hsp70. Pull-down assays revealed that only full-length Hsp70s can interact with Hikeshi. The N-terminal domain (NTD) consists of a jelly-roll/β-sandwich fold structure which contains hydrophobic pockets involved in FG-Nup recognition. A unique extended loop (E-loop) in the NTD is likely to regulate the interactions of Hikeshi with FG-Nups. The crystal structure of Hikeshi explains how Hikeshi participates in the regulation of nuclear import through the recognition of FG-Nups and which part of Hikeshi affects its binding to Hsp70. This study is the first to yield structural insight into this highly unique import receptor.
authors.affiliation: College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
authors.forename: Jinsue
authors.initials: J
authors.lastname: Song
authors.affiliation: Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Kose
authors.affiliation: Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Watanabe
authors.affiliation: College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
authors.forename: Se Young
authors.initials: SY
authors.lastname: Son
authors.affiliation: College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
authors.forename: Saehae
authors.initials: S
authors.lastname: Choi
authors.affiliation: College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
authors.forename: Hyerim
authors.initials: H
authors.lastname: Hong
authors.affiliation: Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Eiki
authors.initials: E
authors.lastname: Yamashita
authors.affiliation: College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
authors.forename: Il Yeong
authors.initials: IY
authors.lastname: Park
authors.affiliation: Cellular Dynamics Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Imamoto
authors.affiliation: College of Pharmacy, Chungbuk National University, 48 Gaeshin-dong, Heungduk-gu, Cheongju, Chungbuk 361-763, Republic of Korea.
authors.forename: Soo Jae
authors.initials: SJ
authors.lastname: Lee
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D018840:HSP70 Heat-Shock Proteins; D009687:Nuclear Proteins; C572913:hikeshi protein, human
keywords: 70 kDa heat-shock proteins; FG-nucleoporins; Hikeshi; asymmetric homodimer; nuclear transport receptor