Lengsin is a survivor of an ancient family of class I glutamine synthetases re-engineered by evolution for a role in the vertebrate lens.

Lengsin is a major protein of the vertebrate eye lens. It belongs to the hitherto purely prokaryotic GS I branch of the glutamine synthetase (GS) superfamily, but has no enzyme activity. Like the taxon-specific crystallins, Lengsin is the result of the recruitment of an ancient enzyme to a noncatalytic role in the vertebrate lens. Cryo-EM and modeling studies of Lengsin show a dodecamer structure with important similarities and differences with prokaryotic GS I structures. GS homology regions of Lengsin are well conserved, but the N-terminal domain shows evidence of dynamic evolutionary changes. Compared with birds and fish, most mammals have an additional exon corresponding to part of the N-terminal domain; however, in human, this is a nonfunctional pseudoexon. Genes related to Lengsin are also present in the sea urchin, suggesting that this branch of the GS I family, supplanted by GS II enzymes in vertebrates, has an ancient role in metazoans.

[1]  D Eisenberg,et al.  The crystal structure of phosphinothricin in the active site of glutamine synthetase illuminates the mechanism of enzymatic inhibition. , 2001, Biochemistry.

[2]  L. Takemoto,et al.  Increased deamidation of asparagine during human senile cataractogenesis. , 2000, Molecular vision.

[3]  H. M. Jernigan.  Urea formation in rat, bovine, and human lens. , 1983, Experimental eye research.

[4]  W. D. de Jong,et al.  The Evolution of an Alternatively Spliced Exon in the αA-Crystallin Gene , 2001, Journal of Molecular Evolution.

[5]  M. Radermacher,et al.  Three-dimensional reconstruction of single particles from random and nonrandom tilt series. , 1988, Journal of electron microscopy technique.

[6]  Graeme Wistow,et al.  Grouping and identification of sequence tags (GRIST): bioinformatics tools for the NEIBank database. , 2002, Molecular vision.

[7]  D. Eisenberg,et al.  Structure-function relationships of glutamine synthetases. , 2000, Biochimica et biophysica acta.

[8]  Sudhir Kumar,et al.  MEGA: Molecular Evolutionary Genetics Analysis software for microcomputers , 1994, Comput. Appl. Biosci..

[9]  J. Lepault,et al.  Electronic Reprint Biological Crystallography on the Fitting of Model Electron Densities into Em Reconstructions: a Reciprocal-space Formulation , 2022 .

[10]  W. W. Jong,et al.  The enzyme lactate dehydrogenase as a structural protein in avian and crocodilian lenses , 1987, Nature.

[11]  A. Prescott,et al.  The eye lens cytoskeleton , 1999, Eye.

[12]  M. Posner,et al.  Gene duplication and separation of functions in αB‐crystallin from zebrafish (Danio rerio) , 2006 .

[13]  J. Leunissen,et al.  Genealogy of the α-crystallin—small heat-shock protein superfamily , 1998 .

[14]  J. Touchman,et al.  Expressed sequence tag analysis of adult human lens for the NEIBank Project: over 2000 non-redundant transcripts, novel genes and splice variants. , 2002, Molecular vision.

[15]  W E O'Brien,et al.  Gene sharing by delta-crystallin and argininosuccinate lyase. , 1988, Proceedings of the National Academy of Sciences of the United States of America.

[16]  D. Hyde,et al.  Expressed sequence tag analysis of zebrafish eye tissues for NEIBank. , 2005, Molecular vision.

[17]  Christine Slingsby,et al.  Ageing and vision: structure, stability and function of lens crystallins. , 2004, Progress in biophysics and molecular biology.

[18]  G. Wistow.  The NEIBank project for ocular genomics: Data-mining gene expression in human and rodent eye tissues , 2006, Progress in Retinal and Eye Research.

[19]  M. Heel,et al.  Exact filters for general geometry three dimensional reconstruction , 1986 .

[20]  T. A. Hall,et al.  BIOEDIT: A USER-FRIENDLY BIOLOGICAL SEQUENCE ALIGNMENT EDITOR AND ANALYSIS PROGRAM FOR WINDOWS 95/98/ NT , 1999 .

[21]  R. Dirks,et al.  Urochordate βγ-Crystallin and the Evolutionary Origin of the Vertebrate Eye Lens , 2005, Current Biology.

[22]  E. L. Smith,et al.  Anomalous cleavage of aspartyl-proline peptide bonds during amino acid sequence determinations. , 1970, Biochemical and biophysical research communications.

[23]  George Harauz,et al.  Resolution criteria for three dimensional reconstruction , 1986 .

[24]  S. Mowbray,et al.  Structure of Mycobacterium tuberculosis glutamine synthetase in complex with a transition-state mimic provides functional insights. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[25]  B. Magasanik,et al.  Asparagine Synthetases of Klebsiella aerogenes: Properties and Regulation of Synthesis , 1982, Journal of bacteriology.

[26]  J. Kuszak,et al.  Fibre cell organization in crystalline lenses. , 2004, Experimental eye research.

[27]  Holger Gohlke,et al.  The Amber biomolecular simulation programs , 2005, J. Comput. Chem..

[28]  L. Takemoto,et al.  Deamidation of Asn-143 of gammaS crystallin from protein aggregates of the human lens , 2001, Current eye research.

[29]  Collaborative Computational,et al.  The CCP4 suite: programs for protein crystallography. , 1994, Acta crystallographica. Section D, Biological crystallography.

[30]  Alfonso Valencia,et al.  The three-dimensional structure of an eukaryotic glutamine synthetase: functional implications of its oligomeric structure. , 2006, Journal of structural biology.

[31]  E. Stadtman,et al.  Regulation of glutamine synthetase. XI. The nature and implications of a lag phase in the Escherichia coli glutamine synthetase reaction. , 1968, Biochemistry.

[32]  A. B. Chepelinsky.  The ocular lens fiber membrane specific protein MIP/Aquaporin 0. , 2003, Journal of experimental zoology. Part A, Comparative experimental biology.

[33]  T. Shearer,et al.  Age-related changes in human lens crystallins identified by two-dimensional electrophoresis and mass spectrometry. , 1998, Experimental eye research.

[34]  W. J. Kent,et al.  BLAT--the BLAST-like alignment tool. , 2002, Genome research.

[35]  J. Piatigorsky,et al.  Lens crystallins: the evolution and expression of proteins for a highly specialized tissue. , 1988, Annual review of biochemistry.

[36]  Graeme Wistow,et al.  A project for ocular bioinformatics: NEIBank. , 2002, Molecular vision.

[37]  M. Kusunoki,et al.  Atomic Structure of Plant Glutamine Synthetase , 2006, Journal of Biological Chemistry.

[38]  J. Harding,et al.  Structural proteins of the mammalian lens: a review with emphasis on changes in development, aging and cataract. , 1976, Experimental eye research.

[39]  D. R. Woods,et al.  Cloning and nucleotide sequence of the Butyrivibrio fibrisolvens gene encoding a type III glutamine synthetase. , 1993, Journal of general microbiology.

[40]  M. Land,et al.  The evolution of eyes. , 1992, Annual review of neuroscience.

[41]  M. Kahn,et al.  ADP-ribosylation of Rhizobium meliloti Glutamine Synthetase III in Vivo(*) , 1995, The Journal of Biological Chemistry.

[42]  Yan A. Su,et al.  AIM1, a novel non-lens member of the βγ-crystallin superfamily, is associated with the control of tumorigenicity in human malignant melanoma , 1997 .

[43]  D. Eisenberg,et al.  Refined atomic model of glutamine synthetase at 3.5 A resolution. , 1989, The Journal of biological chemistry.

[44]  B. Sewell,et al.  Three-dimensional structure of a type III glutamine synthetase by single-particle reconstruction. , 2006, Journal of molecular biology.

[45]  W. O. Saxton,et al.  Principles of organization in S layers. , 1986, Journal of molecular biology.

[46]  G. Wistow.  Molecular biology and evolution of crystallins : gene recruitment and multifunctional proteins in the eye lens , 1995 .

[47]  M van Heel,et al.  A new generation of the IMAGIC image processing system. , 1996, Journal of structural biology.

[48]  Kevin Cowtan,et al.  research papers Acta Crystallographica Section D Biological , 2005 .

[49]  R. Church,et al.  Temporal expression of three mouse lens fiber cell membrane protein genes during early development. , 2002, Molecular vision.

[50]  H. Knull,et al.  Association of glycolytic enzymes with the cytoskeleton. , 1992, Current topics in cellular regulation.

[51]  L. Segovia,et al.  γN‐crystallin and the evolution of the βγ‐crystallin superfamily in vertebrates , 2005, The FEBS journal.

[52]  M. Heel,et al.  Angular reconstitution: a posteriori assignment of projection directions for 3D reconstruction. , 1987 .

[53]  D. Eisenberg,et al.  Structural model for the reaction mechanism of glutamine synthetase, based on five crystal structures of enzyme-substrate complexes. , 1994, Biochemistry.

[54]  J. Piatigorsky,et al.  The recruitment of crystallins: new functions precede gene duplication , 1991, Science.

[55]  Y. Liu,et al.  Isolation and characterization of a novel glutamine synthetase from Rhizobium meliloti. , 1993, The Journal of biological chemistry.

[56]  R. Quinlan.  Cytoskeletal competence requires protein chaperones. , 2002, Progress in molecular and subcellular biology.

[57]  David Eisenberg,et al.  Multicopy crystallographic refinement of a relaxed glutamine synthetase from Mycobacterium tuberculosis highlights flexible loops in the enzymatic mechanism and its regulation. , 2002, Biochemistry.

[58]  J. Piatigorsky,et al.  A pseudo-exon in the functional humanαA-crystallin gene , 1989, Nature.

[59]  G. Wistow,et al.  Lens crystallins: gene recruitment and evolutionary dynamism. , 1993, Trends in biochemical sciences.

[60]  Y Tateno,et al.  Evolution of the glutamine synthetase gene, one of the oldest existing and functioning genes. , 1993, Proceedings of the National Academy of Sciences of the United States of America.