Mammalian homologue of E. coli Ras-like GTPase (ERA) is a possible apoptosis regulator with RNA binding activity.
BACKGROUND
ERA (Escherichia coli Ras-like protein) is an E. coli GTP binding protein that is essential for proliferation. A DNA database search suggests that homologous sequences with ERA exist in various organisms including human, mouse, Drosophila, Caenorhabditis elegans and Antirrhinum majus. However, the physiological function of eukaryotic ERA-like proteins is not known.


RESULTS
We have cloned cDNAs encoding the entire coding region of a human homologue (H-ERA) and a mouse homologue (M-ERA) of ERA. The mammalian homologue of ERA consists of a typical GTPase/GTP-binding domain and a putative K homology (KH) domain, which is known as an RNA binding domain. We performed transfection experiments with wild-type H-ERA or various H-ERA mutants. H-ERA possessing the amino acid substitution mutation into the GTPase domain induced apoptosis of HeLa cells, which was blocked by Bcl-2 expression. Deletion of the C-terminus, which contains a part of the KH domain, alleviated apoptosis by the H-ERA mutant, suggesting the importance of this domain in the function of H-ERA. We have also shown the RNA binding activity of H-ERA by pull-down experiments using RNA homopolymer immobilized on beads or recombinant H-ERA proteins.


CONCLUSIONS
Our data suggest that H-ERA plays an important role in the regulation of apoptotic signalling with its GTPase/GTP binding domain.
Akiyama
T
T
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
Gohda
J
J
Shibata
S
S
Nomura
Y
Y
Azuma
S
S
Ohmori
Y
Y
Sugano
S
S
Arai
H
H
Yamamoto
T
T
Inoue
J
J
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001483:Base Sequence; D015152:Blotting, Northern; D017931:DNA Primers; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D005455:Fluorescent Antibody Technique; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D020287:In Situ Nick-End Labeling; D008969:Molecular Sequence Data; D009154:Mutation; D011499:Protein Processing, Post-Translational; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D051020:bcl-X Protein
C494811:BCL2L1 protein, human; D017931:DNA Primers; D029968:Escherichia coli Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D051020:bcl-X Protein; C068027:era protein, E coli; D019204:GTP-Binding Proteins