TY  - JOUR
A1  - Rinnenthal, Jörg
A1  - Klinkert, Birgit
A1  - Narberhaus, Franz
A1  - Schwalbe, Harald
T1  - Modulation of the stability of the Salmonella fourU-type RNA thermometer
T2  - Nucleic acids research
N2  - RNA thermometers are translational control elements that regulate the expression of bacterial heat shock and virulence genes. They fold into complex secondary structures that block translation at low temperatures. A temperature increase releases the ribosome binding site and thus permits translation initiation. In fourU-type RNA thermometers, the AGGA sequence of the SD region is paired with four consecutive uridines. We investigated the melting points of the wild-type and mutant sequences. It was decreased by 5°C when a stabilizing GC basepair was exchanged by an AU pair or increased by 11°C when an internal AG mismatch was converted to a GC pair, respectively. Stabilized or destabilized RNA structures are directly correlated with decreased or increased in vivo gene expression, respectively. Mg2+ also affected the melting point of the fourU thermometer. Variations of the Mg2+ concentration in the physiological range between 1 and 2 mM translated into a 2.8°C shift of the melting point. Thus, Mg2+ binding to the hairpin RNA is regulatory relevant. Applying three different NMR techniques, two Mg2+ binding sites were found in the hairpin structure. One of these binding sites could be identified as outer sphere binding site that is located within the fourU motif. Binding of the two Mg2+ ions exhibits a positive cooperativity with a Hill coefficient of 1.47. Free energy values delta G for Mg2+ binding determined by NMR are in agreement with data determined from CD measurements. Physiological Mg2+ concentrations reduce enthalpy and entropy values of uncorrelated base pair opening processes for almost all nucleobases.
Y1  - 2001
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/22410
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30-106479
SN  - 0301-5610
SN  - 0305-1048
N1  - © The Author(s) 2011. Published by Oxford University Press. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
VL  - 39
IS  - 18
SP  - 8258
EP  - 8270
PB  - Oxford Univ. Press
CY  - Oxford
ER  -