The covalent structure of the small subunit from Pseudomonas putida amine dehydrogenase reveals the presence of three novel types of internal cross-linkages, all involving cysteine in a thioether bond

Citation
I. Vandenberghe et al., The covalent structure of the small subunit from Pseudomonas putida amine dehydrogenase reveals the presence of three novel types of internal cross-linkages, all involving cysteine in a thioether bond, J BIOL CHEM, 276(46), 2001, pp. 42923-42931
Citations number
21
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
0021-9258 → ACNP
Volume
276
Issue
46
Year of publication
2001
Pages
42923 - 42931
Database
ISI
SICI code
0021-9258(20011116)276:46<42923:TCSOTS>2.0.ZU;2-U
Abstract
Pseudomonas putida contains an amine dehydrogenase that is called a quinohe moprotein as it contains a quinone and two hemes c as redox active groups. Amino acid sequence analysis of the smallest (8.5 kDa), quinone-cofactor-be aring subunit of this heterotrimeric enzyme encountered difficulties in the interpretation of the results at several sites of the polypeptide chain. A s this suggested posttranslational modifications of the subunit, the struct ural genes for this enzyme were determined and mass spectrometric de novo s equencing was applied to several peptides obtained by chemical or enzymatic cleavage. In agreement with the interpretation of the X-ray electronic den sities in the diffraction data for the holoenzyme, our results show that th e polypeptide of the small subunit contains four intrachain cross-linkages in which the sulfur atom of a cysteine residue is involved. Two of these cr oss-linkages occur with the beta -carbon atom of an aspartic acid, one with the gamma -carbon atom of a glutamic acid and the fourth with a tryptophan quinone residue, this adduct constituting the enzyme's quinone cofactor, CT Q. The thioether type bond in all four of these adducts has never been foun d in other proteins. CTQ is a novel cofactor in the series of the recently discovered quinone cofactors.