title: X-ray structures of eIF5B and the eIF5B-eIF1A complex: the conformational flexibility of eIF5B is restricted on the ribosome by interaction with eIF1A.
abstract: eIF5B and eIF1A are two translation-initiation factors that are universally conserved among all kingdoms. They show a unique interaction in eukaryotes which is important for ribosomal subunit joining. Here, the structures of two isolated forms of yeast eIF5B and of the eIF5B-eIF1A complex (eIF1A and eIF5B do not contain the respective N-terminal domains) are reported. The eIF5B-eIF1A structure shows that the C-terminal tail of eIF1A binds to eIF5B domain IV, while the core domain of eIF1A is invisible in the electron-density map. Although the individual domains in all structures of eIF5B or archaeal IF5B (aIF5B) are similar, their domain arrangements are significantly different, indicating high structural flexibility, which is advantageous for conformational change during ribosomal subunit joining. Based on these structures, models of eIF5B, eIF1A and tRNAi(Met) on the 80S ribosome were built. The models suggest that the interaction between the eIF1A C-terminal tail and eIF5B helps tRNAi(Met) to bind to eIF5B domain IV, thus preventing tRNAi(Met) dissociation, stabilizing the interface for subunit joining and providing a checkpoint for correct ribosome assembly.
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Kita 10 Nishi 8 Kita-Ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Aiping
authors.initials: A
authors.lastname: Zheng
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Kita 10 Nishi 8 Kita-Ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Jian
authors.initials: J
authors.lastname: Yu
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Kita 10 Nishi 8 Kita-Ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Reo
authors.initials: R
authors.lastname: Yamamoto
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Kita 10 Nishi 8 Kita-Ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Toyoyuki
authors.initials: T
authors.lastname: Ose
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Kita 10 Nishi 8 Kita-Ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
authors.affiliation: Graduate School of Life Sciences, Hokkaido University, Kita 10 Nishi 8 Kita-Ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Min
authors.initials: M
authors.lastname: Yao
mesh_terms: D018360:Crystallography, X-Ray; D015977:Eukaryotic Initiation Factor-1 / Q000737:chemistry* / Q000378:metabolism; D039642:Eukaryotic Initiation Factors / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011487:Protein Conformation; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D015977:Eukaryotic Initiation Factor-1; D039642:Eukaryotic Initiation Factors; D029701:Saccharomyces cerevisiae Proteins; C451459:eukaryotic initiation factor-5B; C026022:eukaryotic peptide initiation factor-1A
keywords: eIF5B; eIF5B–eIF1A complex