title: GTPases IF2 and EF-G bind GDP and the SRL RNA in a mutually exclusive manner.
abstract: Translational GTPases (trGTPases) are involved in all four stages of protein biosynthesis: initiation, elongation, termination and ribosome recycling. The trGTPases Initiation Factor 2 (IF2) and Elongation Factor G (EF-G) respectively orchestrate initiation complex formation and translocation of the peptidyl-tRNA:mRNA complex through the bacterial ribosome. The ribosome regulates the GTPase cycle and efficiently discriminates between the GDP- and GTP-bound forms of these proteins. Using Isothermal Titration Calorimetry, we have investigated interactions of IF2 and EF-G with the sarcin-ricin loop of the 23S rRNA, a crucial element of the GTPase-associated center of the ribosome. We show that binding of IF2 and EF-G to a 27 nucleotide RNA fragment mimicking the sarcin-ricin loop is mutually exclusive with that of GDP, but not of GTP, providing a mechanism for destabilization of the ribosome-bound GDP forms of translational GTPases.
authors.affiliation: Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia.
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Mitkevich
authors.forename: Viktoriya
authors.initials: V
authors.lastname: Shyp
authors.forename: Irina Yu
authors.initials: IY
authors.lastname: Petrushanko
authors.forename: Aksel
authors.initials: A
authors.lastname: Soosaar
authors.forename: Gemma C
authors.initials: GC
authors.lastname: Atkinson
authors.forename: Tanel
authors.initials: T
authors.lastname: Tenson
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Makarov
authors.forename: Vasili
authors.initials: V
authors.lastname: Hauryliuk
mesh_terms: D001419:Bacteria / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D020653:Peptide Elongation Factor G / Q000378:metabolism*; D039881:Prokaryotic Initiation Factor-2 / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D020653:Peptide Elongation Factor G; D039881:Prokaryotic Initiation Factor-2; D012333:RNA, Messenger; D012338:RNA, Ribosomal, 23S; D012346:RNA, Transfer, Amino Acyl; C019037:tRNA, peptidyl-; D006160:Guanosine Triphosphate