Ribosomal protein
More recently, a near-complete (near)atomic picture of the ribosomal proteins is emerging from the latest high-resolution cryo-EM data (including PDB: 5AFI).
[5] Typically 22 proteins are found in bacterial small subunits and 32 in yeast, human and most likely most other eukaryotic species.
[5] Among the large ribosomal subunit (RPLs), 18 proteins are universal, i.e. found in both bacteria, eukaryotes, and archaea.
Taken together with previous results, 22 of the 54 E. coli ribosomal protein genes can be individually deleted from the genome.
In conjunction with previous reports, 22 ribosomal proteins have been shown to be nonessential in B. subtilis, at least for cell proliferation.
[10] Recent de novo proteomics experiments where the authors characterized in vivo ribosome-assembly intermediates and associated assembly factors from wild-type Escherichia coli cells using a general quantitative mass spectrometry (qMS) approach have confirmed the presence of all the known small and large subunit components and have identified a total of 21 known and potentially new ribosome-assembly-factors that co-localise with various ribosomal particles.
Protein binding to helical junctions is important for initiating the correct tertiary fold of RNA and to organize the overall structure.
[citation needed] Additional stabilization results from the proteins' basic residues, as these neutralize the charge repulsion of the RNA backbone.
Theoretical investigations pointed to correlated effects of protein-binding onto binding affinities during the assembly process[12] In one study, the net charges (at pH 7.4) of the ribosomal proteins comprising the highly conserved S10-spc cluster were found to have an inverse relationship with the halophilicity/halotolerance levels in bacteria and archaea.
[13] In non-halophilic bacteria, the S10-spc proteins are generally basic, contrasting with the overall acidic whole proteomes of the extremely halophiles.
