Open AccessMolecular Properties of Two Mutant Species of the Elongation Factor Tu
Author(s) -
MEIDE Peter H.,
DUISTERWINKEL Feitse,
GRAAF J. Martien,
KRAAL Barend,
BOSCH Leendert,
DOUGLASS James,
BLUMENTHAL Thomas
Publication year - 1981
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1981.tb06294.x
Subject(s) - ef tu , mutant , biology , escherichia coli , gene product , microbiology and biotechnology , ribosome , gene , guanine , biochemistry , nucleotide , gene expression , rna
The molecular properties of two mutant species of the elongation factor Tu (EF‐Tu), derived from either tuf A or tufB , have been studied. One, designated EF‐TuA R , is the product of a kirromycin‐resistant tufA gene. The other designated EF‐TuB o is a tufB product and is present in a kirromycin‐resistant mutant of Escherichia coli (LBE 2012) also harbouring the EF‐TuA R species. EF‐TuA R has been isolated in homogeneous form as a single gene product from the mutant strain LBE 2045, in which the tufB gene has been inactivated by an insertion of the bacteriophage Mu. EF‐TuB o has been isolated from LBE 2012 together with EF‐TuA R in a 1:1 mixture. Fractionation of this mixture on DEAF‐Sephadex A‐50 resulted in an enrichment of EF‐TuB o of about 80%. The properties of EF‐TuA R and EF‐TuB o have been compared to those of a kirromycin‐sensitive species designated EF‐TuA S , which was isolated from LBE2045 by transduction of wild‐type tufA . We show here that all three EF‐Tu species are fully competent to sustain polypeptide synthesis. All also appear to interact normally with guanine nucleotides and EF‐Ts. Only in the presence of the antibiotic do the following differences appear. (a) Kirromycin causes EF‐TuA S (wild‐type tufA gene product) to be retained on, and thus block, the ribosome. (b) EF‐TuA R fails to bind the antibiotic and thus is capable of protein synthesis in its presence. (c) EFTuB o fails to sustain polypeptide synthesis upon binding of kirromycin. It does not, however, block the ribosome, so the strain harbouring both this protein and EF‐TuA R (LBE2012) is kirromycin resistant.