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) 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 CrossRef Citing Articles via Google Scholar Google Scholar Articles by Preneta, R. Articles by Duclos, B. Search for Related Content PubMed PubMed Citation Articles by Preneta, R. Articles by Duclos, B. Agricola Articles by Preneta, R. Articles by Duclos, B.

Autophosphorylation of the 16 kDa and 70 kDa antigens (Hsp 16·3 and Hsp 70) of Mycobacterium tuberculosis

¹ Institut de Biologie et Chimie des Protéines, Centre National de la Recherche Scientifique, Université de Lyon, 7 passage du Vercors, 69367 Lyon Cedex 07, France
² National Institute for Medical Research, Division of Mycobacterial Research, The Ridgeway, Mill Hill, London NW7 1AA, UK

Correspondence
Alain J. Cozzone
aj.cozzone{at}ibcp.fr

Several antigens of Mycobacterium tuberculosis, identified by monoclonal antibodies, have been previously cloned and are being exploited in the development of improved vaccines and diagnostic reagents. In this study, the molecular characteristics of two of these antigens, the immunodominant proteins Hsp 16·3 and Hsp 70, were analysed in further detail by assessing their capacity to undergo protein phosphorylation, a chemical modification frequently used by organisms to adjust to environmental variations. Hsp 16·3 was overproduced in an Escherichia coli expression system and purified to homogeneity. Upon incubation in the presence of radioactive ATP, it was shown to possess autophosphorylation activity. Two-dimensional analysis of its phosphoamino acid content revealed that it was modified exclusively at serine residues. In addition, cross-linking experiments demonstrated that it could tightly bind to ATP. Purified Hsp 70 was also shown to autophosphorylate but phosphorylation occurred exclusively at threonine residues. This reaction was found to be strongly stimulated by calcium ions. These data indicate that both structural and functional similarities exist between Hsp 16·3 (Acr) and -crystallin, a eukaryotic protein which plays an important role in maintaining the transparency of the vertebrate eye, and that the functional properties of Hsp 70 from M. tuberculosis are similar to those of other bacterial members of the Hsp 70 family, particularly the E. coli homologue DnaK.