S16 throws a conformational switch during assembly of 30S 5′ domain

Priya Ramaswamy, Sarah A. Woodson

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Rapid and accurate assembly of new ribosomal subunits is essential for cell growth. Here we show that the ribosomal proteins make assembly more cooperative by discriminating against non-native conformations of the Escherichia coli 16S ribosomal RNA. We used hydroxyl radical footprinting to measure how much the proteins stabilize individual ribosomal RNA tertiary interactions, revealing the free-energy landscape for assembly of the 16S 5′ domain. When ribosomal proteins S4, S17 and S20 bind the 5′ domain RNA, a native and a non-native assembly intermediate are equally populated. The secondary assembly protein S16 suppresses the non-native intermediate, smoothing the path to the native complex. In the final step of 5′ domain assembly, S16 drives a conformational switch at helix 3 that stabilizes pseudoknots in the 30S decoding center. Long-range communication between the S16 binding site and the decoding center helps to explain the crucial role of S16 in 30S assembly.

Original languageEnglish (US)
Pages (from-to)438-445
Number of pages8
JournalNature Structural and Molecular Biology
Issue number4
StatePublished - Apr 2009
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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