Expression and functional assembly into bacterial ribosomes of a nuclear‐encoded chloroplast ribosomal protein with a long NH2‐terminal extension

FEBS Letters

Subramanian, Alap R.¹  Giese, Klaus¹ 

[1] Max-Platick-Institut für Molekulare Genetik, Abteilung Wittmann, Ihnestrasse 73, D-1000 Berlin 33, Germany

关键词: Chloroplast ribosome;    Endosymbiont hypothesis;    LI3 protein expression;    Chloroplast—bacterial hybrid ribosome;    r-protein;    ribosomal protein;    EF-Tu;    clongation factor Tu;    PCR;    polymerase chain reaction;    CTE;    COOH-terminal extension;    NTE;    NH2-terminal extension;    SDS;    sodium dodecyl sulfate;   

DOI  :  10.1016/0014-5793(91)81005-S

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Chloroplast ribosomal protein LI 3 is encoded in the plant nucleus and is considerably larger than its eubacterial homologue by having NH₂- and COOH-terminal extensions with no homology to any known sequences (Phua et al., J. Biol. Chem. 264, 1968–1971, 1989). We made two gene constructs of LI3 cDNA using the polymerase chain reaction (PCR) and expressed them in Escherichia coli. Analysis of the ribosomes and polysomes from these calls, using an antiserum spelific to chloroplast LI3, shows that the expressed proteins are incorporated, in the presence of the homologous E. coli L13, into functional ribosomes which participate in protein synthesis (i.e. polysomes). Evidence is obtained that the large NH₂-terminal extension probably lies on the surface of these ‘mosaic ribosomes’. This first report of the assembly into E. coli ribosomes of a nuclear-coded chloroplast ribosomal protein with terminal extensions thus suggests an extraordinary conservation in the function of eubactcrial type ribosomal proteins, despite the many changes in protein structure during their evolution inside a eukaryotic system.

【 授权许可】

Unknown