HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 277, Issue 38, 34987-34996, September 20, 2002

This Article Full Text Full Text (PDF) All Versions of this Article: 277/38/34987    most recent M202893200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Aubert, E. Articles by Lombardo, D. Search for Related Content PubMed PubMed Citation Articles by Aubert, E. Articles by Lombardo, D. Social Bookmarking                      What's this?

Site-directed Mutagenesis of the Basic N-terminal Cluster of Pancreatic Bile Salt-dependent Lipase
FUNCTIONAL SIGNIFICANCE^*

Emeline Aubert, Véronique Sbarra, Josette Le Petit-Thévenin, Anne Valette, and Dominique Lombardo^§

From the INSERM U-559, Unité de Recherche de Physiopathologie des Cellules Epitheliales, Faculté de Médecine, 27 blv Jean MOULIN, 13385 Marseille cedex 05, France

Previous studies have postulated the presence of a heparin-binding site on the bile salt-dependent lipase (BSDL), whereas two bile salt-binding sites regulate the enzyme activity. One of these sites may overlap with the tentative heparin-binding site at the level of an N-terminal basic cluster consisting of positive residues Lys³², Lys⁵⁶, Lys⁶¹, Lys⁶², and Arg⁶³. The present study uses specific site-directed mutagenesis to determine the functional significance of this basic cluster. Mutations in this sequence resulted in recombinant enzymes that were able to bind to immobilized and to cell-associated heparin before moving throughout intestinal cells. Recombinant BSDL was fully active on soluble substrate, but mutants were less active on micellar cholesteryl oleate in comparison with the wild-type enzyme. Activation studies by primary (sodium taurocholate) and by secondary (sodium taurodeoxycholate) bile salts revealed that the activation of BSDL by sodium taurocholate at concentrations below the critical micellar concentration, and not that evoked by micellar bile salts, was affected by substitutions, suggesting that this N-terminal basic cluster likely represents the specific bile salt-binding site of BSDL. Substitutions also affected the activation of the enzyme promoted by anionic phospholipids, extending the function of this site to that of a cationic regulatory site susceptible to accommodate anionic ligands.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				E. Aubert-Jousset, V. Sbarra, and D. Lombardo Site-directed Mutagenesis of the Distal Basic Cluster of Pancreatic Bile Salt-dependent Lipase J. Biol. Chem., September 17, 2004; 279(38): 39697 - 39704. [Abstract] [Full Text] [PDF]