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From Proteopedia
Crystal Structure of ERA in Complex with GDP
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, composed of an N-terminal GTPase domain followed by an RNA-binding KH domain, is essential for bacterial cell viability. It binds to 16S rRNA and the 30S ribosomal subunit. However, its RNA-binding site, the functional relationship between the two domains, and its role in ribosome biogenesis remain unclear. We have determined two crystal structures of ERA, a binary complex with GDP and a ternary complex with a GTP-analog and the 1531AUCACCUCCUUA1542 sequence at the 3' end of 16S rRNA. In the ternary complex, the first nine of the 12 nucleotides are recognized by the protein. We show that GTP binding is a prerequisite for RNA recognition by ERA and that RNA recognition stimulates its GTP-hydrolyzing activity. Based on these and other data, we propose a functional cycle of ERA, suggesting that the protein serves as a chaperone for processing and maturation of 16S rRNA and a checkpoint for assembly of the 30S ribosomal subunit. The AUCA sequence is highly conserved among bacteria, archaea, and eukaryotes, whereas the CCUCC, known as the anti-Shine-Dalgarno sequence, is conserved in noneukaryotes only. Therefore, these data suggest a common mechanism for a highly conserved ERA function in all three kingdoms of life by recognizing the AUCA, with a "twist" for noneukaryotic ERA proteins by also recognizing the CCUCC. Structure of ERA in complex with the 3' end of 16S rRNA: implications for ribosome biogenesis.,Tu C, Zhou X, Tropea JE, Austin BP, Waugh DS, Court DL, Ji X Proc Natl Acad Sci U S A. 2009 Sep 1;106(35):14843-8. Epub 2009 Aug 17. PMID:19706445[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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