Psychrophilic elongation factor Tu from the antarctic Moraxella sp. Tac II 25: biochemical characterization and cloning of the encoding gene.
The elongation factor Tu was isolated from a psychrophilic eubacterial Antarctic Moraxella strain (MoEF-Tu) and its molecular and functional properties were determined. It catalyzed the synthesis of poly(Phe) and bound specifically guanine nucleotides with an affinity for GDP about 12-fold higher than that for GTP. The affinity toward guanine nucleotides was lower than that of other eubacterial EF-Tu. The intrinsic GTPase activity of MoEF-Tu was hardly detectable but was accelerated by 2 orders of magnitude in the presence of the antibiotic kirromycin (GTPase(k)). Such a property resembled Escherichia coli EF-Tu (EcEF-Tu) even though the affinity of MoEF-Tu for the antibiotic was lower. MoEF-Tu showed a thermophilicity higher than that of EcEF-Tu; its temperature for half-denaturation was 44 degrees C. The MoEF-Tu encoding gene corresponding to E. coli tufA was cloned and sequenced. The translated protein had a calculated molecular weight of 43 288 and contained the GTP-binding sequence motifs. Concerning its primary structure, MoEF-Tu showed sequence identity with E. coli and Thermus thermophilus EF-Tu equal to 84% and 74%, respectively, while the identity with EF-1 alpha from the archaeon Sulfolobus solfataricus was equal to 32%.
Masullo
M
M
Dipartimento di Biochimica e Biotecnologie Mediche, Università di Napoli Federico II, via S. Pansini 5, I-80131, Napoli, Italia.
Arcari
P
P
de Paola
B
B
Parmeggiani
A
A
Bocchini
V
V
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009016:Moraxella / Q000737:chemistry* / Q000235:genetics*; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000235:genetics*; D016415:Sequence Alignment
D001426:Bacterial Proteins; D010444:Peptide Elongation Factor Tu