Ribosome Structure, Function, and Early Evolution

Ribosomes are among the largest and most dynamic molecular motors. The structure and dynamics of translation initiation and elongation are reviewed. Three ribosome motions have been identified for initiation and translocation. A swivel motion between the head/beak and the body of the 30S subunit was observed. A tilting dynamic of the head/beak versus the body of the 30S subunit was detected using simulations. A reversible ratcheting motion was seen between the 30S and the 50S subunits that slide relative to one another. The 30S–50S intersubunit contacts regulate translocation. IF2, EF-Tu, and EF-G are homologous G-protein GTPases that cycle on and off the same site on the ribosome. The ribosome, aminoacyl-tRNA synthetase (aaRS) enzymes, transfer ribonucleic acid (tRNA), and messenger ribonucleic acid (mRNA) form the core of information processing in cells and are coevolved. Surprisingly, class I and class II aaRS enzymes, with distinct and incompatible folds, are homologs. Divergence of class I and class II aaRS enzymes and coevolution of the genetic code are described by analysis of ancient archaeal species.

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Six Rossmannoid folds, including the Class I aminoacyl-tRNA synthetases, share a partial core with the anti-codon-binding domain of a Class II aminoacyl-tRNA synthetase

Bioinformatics ◽

10.1093/bioinformatics/btq039 ◽

2010 ◽

Vol 26 (6) ◽

pp. 709-714 ◽

Cited By ~ 28

Author(s):

S. Cammer ◽

C. W. Carter

Keyword(s):

Class Ii ◽

Trna Synthetase ◽

Binding Domain ◽

Class I ◽

Aminoacyl Trna Synthetase ◽

Trna Synthetases ◽

Aminoacyl Trna Synthetases

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The Human EPRS Locus (Formerly the QARS Locus): A Gene Encoding a Class I and a Class II Aminoacyl-tRNA Synthetase

Genomics ◽

10.1006/geno.1994.1059 ◽

1994 ◽

Vol 19 (2) ◽

pp. 280-290 ◽

Cited By ~ 16

Author(s):

Eva Kaiser ◽

Bing Hu ◽

Stefanie Becher ◽

Dirk Eberhard ◽

Beate Schray ◽

...

Keyword(s):

Class Ii ◽

Trna Synthetase ◽

Class I ◽

Aminoacyl Trna Synthetase ◽

Gene Encoding

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Active Site Nanospace of Aminoacyl tRNA Synthetase: Difference Between the Class I and Class II Synthetases

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2014.8534 ◽

2014 ◽

Vol 14 (3) ◽

pp. 2280-2298 ◽

Cited By ~ 9

Author(s):

Saheb Dutta ◽

Kaberi Choudhury ◽

Sindrila Dutta Banik ◽

Nilashis Nandi

Keyword(s):

Active Site ◽

Class Ii ◽

Trna Synthetase ◽

Class I ◽

Aminoacyl Trna Synthetase

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Widespread and selective induction of major histocompatibility complex-determined antigens in vivo by gamma interferon.

Journal of Experimental Medicine ◽

10.1084/jem.162.5.1645 ◽

1985 ◽

Vol 162 (5) ◽

pp. 1645-1664 ◽

Cited By ~ 264

Author(s):

M J Skoskiewicz ◽

R B Colvin ◽

E E Schneeberger ◽

P S Russell

Keyword(s):

Dendritic Cells ◽

Small Intestine ◽

Antigen Expression ◽

Class Ii ◽

Gamma Interferon ◽

The Body ◽

Class I ◽

Ifn Gamma ◽

Histocompatibility Complex

gamma Interferon (IFN-gamma) caused remarkable increases in class I (H-2Kk) and class II (I-Ak) antigens throughout the body by 6-9 d. Heart, kidney, and adrenals showed increases of 4-8 times their previous levels of class I antigen content, while the pancreas and small intestine increased 13-17-fold. Lesser increases were found in spleen, liver, and lung, which showed higher resting antigenic potency. Increases of class II antigenicity of 6-10-fold were found in heart, kidney, pancreas, lung, liver, adrenal, and small intestine, with lesser increases in thymus and spleen, and none in lymph node. Topographical analysis revealed that IFN-gamma induced class I and II antigens on most tissues in a highly selective fashion. For example, the renal proximal tubules expressed large amounts of both class I and II antigens, whereas the distal tubules and collecting ducts did not. In some epithelial cells class I and II determinants were induced only on the basal aspects of the cell membrane. IFN-gamma caused a remarkable increase in class II-positive dendritic cells in the liver, pancreas, salivary glands, and thyroid. Whether these cells were of local or systemic origin is uncertain, but the finding of a simultaneous depletion of dendritic cells from lymph nodes and spleen raises the possibility that they may have been derived, at least in part, from these sites. The dynamic and selective induction of class I and II antigen expression by IFN-gamma is likely to be important in regulation of the immune response in tissues.

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