type	Journal Article
authors	Engelhardt, H.; Forchhammer, K.; Muller, S.; Goldie, K. N.; Bock, A.
title	Structure of selenocysteine synthase from Escherichia coli and location of tRNA in the seryl-tRNA(sec)-enzyme complex
journal	Mol Microbiol
Activity	2.9.1.1
ui	93116584
year	(1992)
volume	6
number	23
pages	3461-7.
keywords	Bacterial Proteins/ultrastructure
abstract	Selenocysteine synthase of Escherichia coli catalyses the biosynthesis of selenocysteine in the form of the aminoacyl-tRNA complex, the reaction intermediate being aminoacrylyl-tRNA(sec) covalently bound to the prosthetic group of the enzyme. Selenocysteine synthase and the specific aminoacrylyl-tRNA(sec)-enzyme complex as well as the isolated seryl-tRNA(sec) were investigated in the electron microscope and analysed by means of image processing to a resolution of 2 nm in projection. The stoichiometric composition of the selenocysteine synthase molecule was elucidated by scanning transmission electron microscopic mass determination. The enzyme has a fivefold symmetric structure and consists of 10 monomers arranged in two rings. The tRNA is bound near the margin of the dimeric subunits. Principal component analysis of the tRNA-enzyme complexes revealed that the selenocysteine synthase appears to bind only one seryl-tRNA(sec) per dimer, which is consistent with the result of biochemical binding studies.
last changed	2002/11/12 16:17