Ribosomal subunits, halophilic proteins

Components of the archaeal translation apparatus, however, display an intra-domain diversity, not encountered within the other two domains. This situation is exemplified by (i) the lack of a uniform compatibility between ribosomes and elongation factors from different archaeal lineages (see section 5.2) (ii) the impressive diversity of archaeal ribosomes and factors in their response to a host of protein synthesis inhibitors (see section 4) (iii) the heterogeneity in shape, mass and composition of archaeal ribosomal subunits (see sections 2.6.2, 2.6.3). Importantly, within-domain diversity is also exemplified by the different complexities of the RNA polymerase subunit patterns from the sulfur-dependent and the methanogenic-halophilic archaea (see Zillig et ah. Chapter 12 of this volume). 

It is now possible to specifically modify the individual rRNA and r-protein molecules that form the archaeal ribosome, enabling one to study the structural/functional relationships of these molecules. Recent studies on the reconstitution of the archaeal 508 ribosomal subunit from the extreme halophile Haloferax mediterranei [20] and the extreme thermophile Sulfolobus solfataricus [21] open the way for the identification of the individual functions of the r-proteins in these particles. Experiments on site-specific changes in the r-protein LI2 from Sulfolobus and their effect on the structure and function of the ribosome are described later in this chapter. 

Yonath, A. High-resolution structures of large ribosomal subunits from mesophilic eubacteria and halophilic archaea at various functional states. Curr. Protein Pept. Sci. 2002, 3(1), 67. 

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