Molecular and General Genetics MGG

, Volume 214, Issue 3, pp 588–591 | Cite as

Chloroplast ribosomal protein L-18 in Chlamydomonas reinhardtii is processed during ribosome assembly

  • Xiang-Qin Liu
  • Nicholas W. Gillham
  • John E. Boynton
Short Communications


Chloroplast ribosomal protein L-18 is made in the cytoplasm as a precursor, imported into the chloroplast, and processed to the mature form in two steps. We report here that the intermediate produced following the first processing step associates specifically with a ribosomal complex migrating with the chloroplast ribosome large subunit peak in sucrose gradients, and is then processed into mature L-18. This processing event is slowed down in mutant cells deficient in synthesis of non-ribosomal proteins in the chloroplast. Thus the second processing step of L-18 occurs during ribosome assembly, depends on one or more nonribosomal proteins made in the chloroplast, and may be required for the maturation of the 50 S ribosome subunit. The mature L-18 protein shows extensive sequence homology at its amino-terminus to Escherichia coli ribosomal protein L27, which is located at the interface, between 30 S and 50 S subunits and is involved in the formation of the peptidyl-tRNA binding site.

Key words

Chloroplast Ribosome assembly Ribosomal protein 


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Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Xiang-Qin Liu
    • 1
  • Nicholas W. Gillham
    • 2
  • John E. Boynton
    • 1
  1. 1.Department of BotanyDuke UniversityDurhamUSA
  2. 2.Department of ZoologyDuke UniversityDurhamUSA

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