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Crystal Structure of Translation Initiation Factor 5A from Pyrococcus Horikoshii
Structural highlights
FunctionIF5A_PYRHO Functions by promoting the formation of the first peptide bond (By similarity). 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 PubMedEukaryotic initiation factor 5A (eIF-5A) is ubiquitous in eukaryotes and archaebacteria and is essential for cell proliferation and survival. The crystal structure of the eIF-5A homologue (PhoIF-5A) from a hyperthermophilic archaebacterium Pyrococcus horikoshii OT3 was determined at 2.0 A resolution by the molecular replacement method. PhoIF-5A is predominantly composed of beta-strands comprising two distinct folding domains, an N-domain (residues 1-69) and a C-domain (residues 72-138), connected by a short linker peptide (residues 70-71). The N-domain has an SH3-like barrel, while the C-domain folds in an (oligonucleotide/oligosaccharide binding) OB fold. Comparison of the structure of PhoIF-5A with those of archaeal homologues from Methanococcus jannaschii and Pyrobaculum aerophilum showed that the N-domains could be superimposed with root mean square deviation (rmsd) values of 0.679 and 0.624 A, while the C-domains gave higher values of 1.824 and 1.329 A, respectively. Several lines of evidence suggest that eIF-5A functions as a biomodular protein capable of interacting with protein and nucleic acid. The surface representation of electrostatic potential shows that PhoIF-5A has a concave surface with positively charged residues between the N- and C-domains. In addition, a flexible long hairpin loop, L1 (residues 33-41), with a hypusine modification site is positively charged, protruding from the N-domain. In contrast, the opposite side of the concave surface at the C-domain is mostly negatively charged. These findings led to the speculation that the concave surface and loop L1 at the N-domain may be involved in RNA binding, while the opposite side of the concave surface in the C-domain may be involved in protein interaction. Crystal structure of hyperthermophilic archaeal initiation factor 5A: a homologue of eukaryotic initiation factor 5A (eIF-5A).,Yao M, Ohsawa A, Kikukawa S, Tanaka I, Kimura M J Biochem. 2003 Jan;133(1):75-81. PMID:12761201[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References | ||||||||||||||||||
