Publication Date:
2009-07-18
Description:
Selenocysteine is the only genetically encoded amino acid in humans whose biosynthesis occurs on its cognate transfer RNA (tRNA). O-Phosphoseryl-tRNA:selenocysteinyl-tRNA synthase (SepSecS) catalyzes the final step of selenocysteine formation by a poorly understood tRNA-dependent mechanism. The crystal structure of human tRNA(Sec) in complex with SepSecS, phosphoserine, and thiophosphate, together with in vivo and in vitro enzyme assays, supports a pyridoxal phosphate-dependent mechanism of Sec-tRNA(Sec) formation. Two tRNA(Sec) molecules, with a fold distinct from other canonical tRNAs, bind to each SepSecS tetramer through their 13-base pair acceptor-TPsiC arm (where Psi indicates pseudouridine). The tRNA binding is likely to induce a conformational change in the enzyme's active site that allows a phosphoserine covalently attached to tRNA(Sec), but not free phosphoserine, to be oriented properly for the reaction to occur.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857584/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857584/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Palioura, Sotiria -- Sherrer, R Lynn -- Steitz, Thomas A -- Soll, Dieter -- Simonovic, Miljan -- R01 GM022854/GM/NIGMS NIH HHS/ -- R01 GM022854-33/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2009 Jul 17;325(5938):321-5. doi: 10.1126/science.1173755.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19608919" target="_blank"〉PubMed〈/a〉
Keywords:
Amino Acyl-tRNA Synthetases/*chemistry/*metabolism
;
Base Sequence
;
Biocatalysis
;
Catalytic Domain
;
Crystallography, X-Ray
;
Humans
;
Hydrogen Bonding
;
Models, Molecular
;
Molecular Sequence Data
;
Nucleic Acid Conformation
;
Phosphates/chemistry/metabolism
;
Phosphoserine/chemistry/metabolism
;
Protein Conformation
;
Protein Multimerization
;
Protein Structure, Secondary
;
RNA, Transfer, Amino Acid-Specific/*chemistry/*metabolism
;
RNA, Transfer, Amino Acyl/*metabolism
;
Selenocysteine/*biosynthesis/genetics
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
