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

This Article Full Text Full Text (PDF) Corrigendum Alert me when this article is cited 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 Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Kingston, K. B. Articles by Jacques, N. A. Search for Related Content PubMed PubMed Citation Articles by Kingston, K. B. Articles by Jacques, N. A. Agricola Articles by Kingston, K. B. Articles by Jacques, N. A.

Role of the C-terminal YG repeats of the primer-dependent streptococcal glucosyltransferase, GtfJ, in binding to dextran and mutan

Institute of Dental Research, Centre for Oral Health, Westmead Hospital, PO Box 533, Wentworthville, NSW 2145, Australia¹

Author for correspondence: Nicholas A. Jacques. Tel: +61 2 9845 8763. Fax: +61 2 9845 7599. e-mail: njacques{at}dental.wsahs.nsw.gov.au

The recombinant primer-dependent glucosyltransferase GtfJ of Streptococcus salivarius possesses a C-terminal glucan-binding domain composed of eighteen 21 aa YG repeats. By engineering a series of C-terminal truncated proteins, the position at which truncation prevented further mutan synthesis was defined to a region of 43 aa, confirming that not all of the YG motifs were required for the formation of mutan by GtfJ. The role of the YG repeats in glucan binding was investigated in detail. Three proteins consisting of 3·8, 7·2 or 11·0 C-terminal YG repeats were expressed in Escherichia coli. Each of the three purified proteins bound to both the 1,6--linked glucose residues of dextran and the 1,3--linked glucose residues of mutan, indicating that a protein consisting of nothing but 3·8 YG repeats could attach to either substrate. Secondary structure predictions of the primary amino acid sequence suggested that 37% of the amino acids were capable of forming a structure such that five regions of ß-sheet were separated by regions capable of forming ß-turns and random coils. CD spectral analysis showed that the purified 3·8 YG protein possessed an unordered secondary structure with some evidence of possible ß-sheet formation and that the protein maintained this relatively unordered structure on binding to dextran.

Keywords: Streptococcus, protein structure, circular dichroism

Abbreviations: CD, circular dichroism; Gtf, glucosyltransferase; Gtf-I, water-insoluble glucosyltransferase; Gtf-S, water-soluble glucosyltransferase; GBD, glucan-binding domain; GST, glutathione S-transferase

^a Present address: Agriculture Victoria – Rutherglen, RMB 1145, Chiltern Valley Road, Rutherglen, Victoria 2685, Australia.

This article has been cited by other articles:

				S. A. F. T. van Hijum, S. Kralj, L. K. Ozimek, L. Dijkhuizen, and I. G. H. van Geel-Schutten Structure-Function Relationships of Glucansucrase and Fructansucrase Enzymes from Lactic Acid Bacteria Microbiol. Mol. Biol. Rev., March 1, 2006; 70(1): 157 - 176. [Abstract] [Full Text] [PDF]

				D. S. H. Shah, G. Joucla, M. Remaud-Simeon, and R. R. B. Russell Conserved Repeat Motifs and Glucan Binding by Glucansucrases of Oral Streptococci and Leuconostoc mesenteroides J. Bacteriol., December 15, 2004; 186(24): 8301 - 8308. [Abstract] [Full Text] [PDF]

				J.A. Banas and M.M. Vickerman GLUCAN-BINDING PROTEINS OF THE ORAL STREPTOCOCCI Critical Reviews in Oral Biology & Medicine, March 1, 2003; 14(2): 89 - 99. [Abstract] [Full Text] [PDF]