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Infection and Immunity, July 2009, p. 2703-2711, Vol. 77, No. 7
0019-9567/09/$08.00+0     doi:10.1128/IAI.00157-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Glyceraldehyde-3-Phosphate Dehydrogenase Is a Surface-Associated, Fibronectin-Binding Protein of Trichomonas vaginalis {triangledown}

A. Lama, A. Kucknoor, V. Mundodi, and J. F. Alderete*

School of Molecular Biosciences, Washington State University, Pullman, Washington 99164

Received 10 February 2009/ Returned for modification 18 March 2009/ Accepted 11 April 2009

Trichomonas vaginalis colonizes the urogenital tract of humans and causes trichomonosis, the most prevalent nonviral sexually transmitted disease. We have shown an association of T. vaginalis with basement membrane extracellular matrix components, a property which we hypothesize is important for colonization and persistence. In this study, we identify a fibronectin (FN)-binding protein of T. vaginalis. A monoclonal antibody (MAb) from a library of hybridomas that inhibited the binding of T. vaginalis organisms to immobilized FN was identified. The MAb (called ws1) recognized a 39-kDa protein and was used to screen a cDNA expression library of T. vaginalis. A 1,086-bp reactive cDNA clone that encoded a protein of 362 amino acids with identity to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was obtained. The gapdh gene was cloned, and recombinant GAPDH (rGAPDH) was expressed in Escherichia coli cells. Natural GAPDH and rGAPDH bound to immobilized FN and to plasminogen and collagen but not to laminin. MAb ws1 inhibited binding to FN. GAPDH was detected on the surface of trichomonads and was upregulated in synthesis and surface expression by iron. Higher levels of binding to FN were seen for organisms grown in iron-replete medium than for organisms grown in iron-depleted medium. In addition, decreased synthesis of GAPDH by antisense transfection of T. vaginalis gave lower levels of organisms bound to FN and had no adverse effect on growth kinetics. Finally, GAPDH did not associate with immortalized vaginal epithelial cells (VECs), and neither GAPDH nor MAb ws1 inhibited the adherence of trichomonads to VECs. These results indicate that GAPDH is a surface-associated protein of T. vaginalis with alternative functions.

* Corresponding author. Mailing address: School of Molecular Biosciences, Washington State University, Pullman, WA 99164. Phone: (509) 335-8125. Fax: (509) 335-4159. E-mail: alderete{at}wsu.edu

{triangledown} Published ahead of print on 20 April 2009.

Editor: W. A. Petri, Jr.

Infection and Immunity, July 2009, p. 2703-2711, Vol. 77, No. 7
0019-9567/09/$08.00+0     doi:10.1128/IAI.00157-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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