STRUCTURE OF A PROTEOLYTIC FRAGMENT OF TLP20

Citation
Hm. Holden et al., STRUCTURE OF A PROTEOLYTIC FRAGMENT OF TLP20, Acta crystallographica. Section D, Biological crystallography, 52, 1996, pp. 1153-1160
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Crystallography,"Biochemical Research Methods",Biology
ISSN journal
0907-4449
Volume
52
Year of publication
1996
Part
6
Pages
1153 - 1160
Database
ISI
SICI code
0907-4449(1996)52:<1153:SOAPFO>2.0.ZU;2-J
Abstract
Myosin light-chain kinase is responsible for the phosphorylation of my osin in smooth muscle cells. In some tissue types, the C-terminal port ion of this large enzyme is expressed as an independent protein and ha s been given the name telokin. Recently, an antibody directed against telokin was found to interact with a protein derived from the baculovi rus Autographa californica nuclear polyhedrosis virus. This protein wa s biochemically characterized and given the name TLP20 for telokin-lik e protein of 20000 molecular weight. The amino-acid sequence of TLP20 was determined on the basis of a cDNA clone and subsequent alignment s earches failed to reveal any homology to telokin or to other known pro teins. The three-dimensional structure of a proteolytic portion of TLP 20 is reported here. Crystals employed in the investigation were grown from ammonium sulfate solutions at pH 6.0 and belonged to the space g roup P2(1)3 with unit-cell dimensions of a = b = c = 76.3 Angstrom and one molecule per asymmetric unit. The structure was determined by mul tiple isomorphous replacement with three heavy-atom derivatives. Least -squares refinement of the model reduced the crystallographic R factor to 18.1% for all measured X-ray data from 30.0 to 2.2 Angstrom. The o verall fold of the molecule may be described as a seven-stranded antip arallel beta-barrel flanked on the bottom by two additional beta-stran ds and on the top by an alpha-helix. Quite surprisingly, the three-dim ensional structure of this beta-barrel is not similar to telokin or to any other known protein.