Affinity of ribosomal protein S8 from mesophilic and (hyper)thermophilic archaea and bacteria for 16S rRNA correlates with the growth temperatures of the organisms

Abstract

The ribosomal protein S8 plays a pivotal role in the assembly of the 30S ribosomal subunit. Using ¢lter binding assays, S8 proteins from mesophilic, and (hyper)thermophilic species of the archaeal genus Methanococcus and from the bacteria Escherichia coli and Thermus thermophilus were tested for their a⁄nity to their speci¢c 16S rRNA target site. S8 proteins from hyperthermophiles exhibit a 100-fold and S8 from thermophiles exhibit a 10-fold higher a⁄nity than their mesophilic counterparts. Thus, there is a striking correlation of a⁄nity of S8 proteins for their speci¢c RNA binding site and the optimal growth temperatures of the respective organisms. The stability of individual rRNA-protein complexes might modulate the stability of the ribosome, providing a maximum of thermostability and £exibility at the growth temperature of the organism. ß

Structure analysis of free and bound states of an RNA aptamer against ribosomal protein S8 from Bacillus anthracis

“…The affinity of E. coli r-protein S8 for the helix 21 sequence element is consistent with filter-binding measurements (9,10,12). Filter binding experiments using the archaeal Methanococcus vannielii S8 protein yielded an apparent K d for its 16S rRNA helix 21 binding site of 220 nM, an affinity similar to that of the Bacillus S8 protein for helix 21 (44). S8 proteins from thermophilic and hyperthermophilic archael organisms show 10- to 100-fold tighter binding to their respective 16S rRNA targets (17,44).…”

“…Filter binding experiments using the archaeal Methanococcus vannielii S8 protein yielded an apparent K d for its 16S rRNA helix 21 binding site of 220 nM, an affinity similar to that of the Bacillus S8 protein for helix 21 (44). S8 proteins from thermophilic and hyperthermophilic archael organisms show 10- to 100-fold tighter binding to their respective 16S rRNA targets (17,44). The affinity of Aquifex aeolicus S8 protein for the minimal RNA binding site is 1.5 nM, but the protein has very high affinity (0.018 nM) for an RNA construct containing the three-way junction formed by Helices-20–21–22 (17).…”

RNA Tertiary Structure and Cooperative Assembly of a Large Ribonucleoprotein Complex

“…A correlation between the affinity of S8 for 16 S rRNA and the optimal growth temperature of the organism has been observed for members of the genus Methanococcus, but the highest affinity interaction is still nearly three orders of magnitude weaker than the Aquifex S8-16 S rRNA interaction. 27 The Aquifex S8 protein is about 30 amino acid residues larger than any other S8 protein, which may contribute to its unusually high affinity for 16 S rRNA. A study of the molecular basis for the high-affinity binding of AS8 to Aquifex 16 S rRNA is in progress.…”

Interactions of the N-terminal Domain of Ribosomal Protein L11 with Thiostrepton and rRNA

“…We have found similar, ϳ100-fold differences in the affinities of E. coli and B. stearothermophilus ribosomal protein-rRNA complexes in two other cases, S4 (43) and L3. 4 A systematic study of ribosomal protein S8 homologs from meso-, thermo-, and hyperthermophilic sources also found a 100-fold range in rRNA binding affinities that correlated with growth temperature (44). Whether the higher RNA affinity of thermophilic proteins is entirely because of a more stable protein fold or also to a more favorable set of protein-RNA contacts has not been examined.…”