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Titolo:
Translational regulation by modifications of the elongation factor Tu
Autore:
Kraal, B; Lippmann, C; Kleanthous, C;
Indirizzi:
Leiden Univ, LIC, Dept Biochem, NL-2300 RA Leiden, Netherlands Leiden Univ Leiden Netherlands NL-2300 RA NL-2300 RA Leiden, Netherlands Free Univ Berlin, Inst Biochem, D-1000 Berlin, Germany Free Univ Berlin Berlin Germany D-1000 t Biochem, D-1000 Berlin, Germany Univ E Anglia, Sch Biol Sci, Norwich NR4 7TJ, Norfolk, England Univ E Anglia Norwich Norfolk England NR4 7TJ h NR4 7TJ, Norfolk, England
Titolo Testata:
FOLIA MICROBIOLOGICA
fascicolo: 2, volume: 44, anno: 1999,
pagine: 131 - 141
SICI:
0015-5632(1999)44:2<131:TRBMOT>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
FACTOR EF-TU; ESCHERICHIA-COLI; CRYSTAL-STRUCTURE; TERNARY COMPLEX; TRANSFER-RNA; INSULIN STIMULATION; PROTEIN-SYNTHESIS; EFFECTOR REGION; PHOSPHORYLATION; GTP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Kraal, B Leiden Univ, LIC, Dept Biochem, NL-2300 RA Leiden, Netherlands Leiden Univ Leiden Netherlands NL-2300 RA A Leiden, Netherlands
Citazione:
B. Kraal et al., "Translational regulation by modifications of the elongation factor Tu", FOL MICROB, 44(2), 1999, pp. 131-141

Abstract

EF-Tu from E. coli, one of the superfamily of GTPase switch proteins, plays a central role in the fast and accurate delivery of aminoacyl-tRNAs to the translating ribosome. An overview is given about the regulatory effects of methylation, phosphorylation and phage-induced cleavage of EF-Tu on its function. During exponential growth, EF-Tu becomes monomethylated at Lys(56)which is converted to Me(2)Lys upon entering the stationary phase. Lys(56)is in the GTPase switch-1 region (residues 49-62), a strongly conserved site involved in interactions with the nucleotide and the 5' end of tRNA. Methylation was found to attenuate GTP hydrolysis and may thus enhance translational accuracy. In vivo 5-10 % of EF-Tu is phosphorylated at Thr(382) by, ribosome-associated kinase. In EF-Tu-GTP, Thr(382) in domain 3 has a strategic position in the interface with domain I; it is hydrogen-bonded to Glu(117) that takes part in the switch-2 mechanism, and is close to the T-stem binding site of the tRNA, in a region known for many kirromycin-resistance mutations. Phosphorylation is enhanced by EF-Ts, but inhibited by kirromycin. In reverse, phosphorylated EF-Tu has an increased affinity for EF-Ts, does not bind kirromycin and can no longer bind aminoacyl tRNA. The in vivo role of this reversible modification is still a matter of speculation. T4 infection of E, coli may trigger a phage-exclusion mechanism by activation of Lit, a host-encoded proteinase. As a result, EF-Tu is cleaved site-specifically between Gly(59)-Ile(60) in the switch-1 region. Translation was found to drop beyond a minimum level. Interestingly, the identical sequence in the related EF-G appeared to remain fully intact. Although the Lit cleavage-mechanism may eventually lead to programmed cell death, the very efficient prevention of phage multiplication may be caused by a novel mechanism of in cis inhibition of late T4 mRNA translation.

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Documento generato il 15/07/20 alle ore 20:56:44