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CRYSTAL STRUCTURE OF A WIDELY CONSERVED GTPASE ERA
Structural highlights
FunctionERA_ECOLI An essential GTPase that binds both GDP and GTP, with nucleotide exchange occurring on the order of seconds whereas hydrolysis occurs on the order of minutes. Plays a role in numerous processes, including cell cycle regulation, energy metabolism, as a chaperone for 16S rRNA processing and 30S ribosomal subunit biogenesis. Its presence in the 30S subunit may prevent translation initiation. Seems to be critical for maintaining cell growth and cell divison rates; a dramatic reduction in Era protein levels temporarily arrests cell growth just before cytokinesis (at the predivisional two-cell stage) and delays cell division. Era mutant era1 suppresses some temperature-sensitive mutations that affect DNA replication and chromosome partitioning and segregation. The dominant-negative Era-de mutant which is missing residues in a putative effector region, is unable to complement the disruption mutant; upon overproduction it shows a significant decrease in cell viability and a synthetic lethal phenotype in the presence of acetate. Era function probably overlaps RbfA. Binds to the pre-30S subunit through several stages of protein assembly.[1] [2] [3] [4] [5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedERA forms a unique family of GTPase. It is widely conserved and essential in bacteria. ERA functions in cell cycle control by coupling cell division with growth rate. ERA homologues also are found in eukaryotes. Here we report the crystal structure of ERA from Escherichia coli. The structure has been determined at 2.4-A resolution. It reveals a two-domain arrangement of the molecule: an N-terminal domain that resembles p21 Ras and a C-terminal domain that is unique. Structure-based topological search of the C domain fails to reveal any meaningful match, although sequence analysis suggests that it contains a KH domain. KH domains are RNA binding motifs that usually occur in tandem repeats and exhibit low sequence similarity except for the well-conserved segment VIGxxGxxIK. We have identified a betaalphaalphabeta fold that contains the VIGxxGxxIK sequence and is shared by the C domain of ERA and the KH domain. We propose that this betaalphaalphabeta fold is the RNA binding motif, the minimum structural requirement for RNA binding. ERA dimerizes in crystal. The dimer formation involves a significantly distorted switch II region, which may shed light on how ERA protein regulates downstream events. Crystal structure of ERA: a GTPase-dependent cell cycle regulator containing an RNA binding motif.,Chen X, Court DL, Ji X Proc Natl Acad Sci U S A. 1999 Jul 20;96(15):8396-401. PMID:10411886[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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