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Asparagine‐135 of elongation factor Tu is a crucial residue for the folding of the guanine nucleotide binding pocket
Author(s) -
Weijland Albert,
Sarfati Robert,
Bârzu Octavian,
Parmeggiani Andrea
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80899-6
Subject(s) - gtp' , nucleotide , ribosome , ef tu , guanine , chemistry , gtpase , biochemistry , binding site , elongation factor , guanosine triphosphate , stereochemistry , enzyme , rna , gene
This work studies the structure‐function relationships of Asn 135 , a residue situated in the GTP binding pocket of elongation factor Tu (EF‐Tu). For this purpose we constructed EF‐TuN135D/D138N and assayed its reactivity towards various purine nucleotides. We found that EF‐TuN135D/D138N had no functional effect with GTP, ATP, XTP and iso GTP. The lack of a productive interaction with iso GTP shows that the Asn 135 side‐chain does not recognize the exocyclic keto group of the guanine base. However, EF‐TuN 135D/D 138N, whose native conformation is stabilized by either elongation factor Ts or kirromycin, was able to support the enzymatic binding of aa‐tRNA to the ribosome in the absence of any nucleotide, when in complex with the antibiotic. Taken together, these results show that Asn 135 is important for the correct folding of the nucleotide binding site and that EF‐Tu·kirromycin can mediate the binding of aa‐tRNA to the mRNA‐programmed ribosomes independently of the native conformation of this site.