biostudies-literatureJiang JNIHNIGMS NIH HHS48-55https://www.ebi.ac.uk/biostudies/studies/S-EPMC4414897biostudies-literatureUnknown200-201Centrally located at the ribosomal subunit interface and mRNA tunnel, helix 69 (H69) from 23S rRNA participates in key steps of translation. Ribosome activity is influenced by three pseudouridine modifications, which modulate the structure and conformational behavior of H69. To understand how H69 is affected by the presence of pseudouridine in combination with sequence changes, the biophysical properties of wild-type H69 and representative mutants (A1912G, U1917C, and A1919G) were examined. Results from NMR and circular dichroism spectroscopy indicate that pH-dependent structural changes of wild-type H69 and the chosen mutants are modulated by pseudouridine and loop sequence. The effects of the mutations on global stability of H69 are negligible; however, pseudouridine stabilizes H69 at loBiophysical chemistryModulation of conformational changes in helix 69 mutants by pseudouridine modifications.PMC4414897GM087596R01 GM087596Jiang JKharel DNChow CSfalseModulation of conformational changes in helix 69 mutants by pseudouridine modifications.Centrally located at the ribosomal subunit interface and mRNA tunnel, helix 69 (H69) from 23S rRNA participates in key steps of translation. Ribosome activity is influenced by three pseudouridine modifications, which modulate the structure and conformational behavior of H69. To understand how H69 is affected by the presence of pseudouridine in combination with sequence changes, the biophysical properties of wild-type H69 and representative mutants (A1912G, U1917C, and A1919G) were examined. Results from NMR and circular dichroism spectroscopy indicate that pH-dependent structural changes of wild-type H69 and the chosen mutants are modulated by pseudouridine and loop sequence. The effects of the mutations on global stability of H69 are negligible; however, pseudouridine stabilizes H69 at lo2015-01-01T00:00:00Z2015 May-Jun2025-04-19T00:49:46.972Z2019-03-27T01:50:45ZS-EPMC44148972580068010.1016/j.bpc.2015.03.001