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Infection and Immunity, September 2009, p. 3533-3541, Vol. 77, No. 9
0019-9567/09/$08.00+0     doi:10.1128/IAI.00081-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Amino Acid Changes in Elongation Factor Tu of Mycoplasma pneumoniae and Mycoplasma genitalium Influence Fibronectin Binding{triangledown}

Sowmya Balasubramanian,1 T. R. Kannan,1 P. John Hart,2,3 and Joel B. Baseman1*

Department of Microbiology and Immunology,1 Department of Biochemistry, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, Texas 78229-3900,2 Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, South Texas Veterans Health Care System, The University of Texas Health Science Center at San Antonio, San Antonio, Texas 782293

Received 21 January 2009/ Returned for modification 12 March 2009/ Accepted 13 June 2009

Mycoplasma pneumoniae and Mycoplasma genitalium are closely related organisms that cause distinct clinical manifestations and possess different tissue predilections despite their high degree of genome homology. We reported earlier that surface-localized M. pneumoniae elongation factor Tu (EF-TuMp) mediates binding to the extracellular matrix component fibronectin (Fn) through the carboxyl region of EF-Tu. In this study, we demonstrate that surface-associated M. genitalium EF-Tu (EF-TuMg), in spite of sharing 96% identity with EF-TuMp, does not bind Fn. We utilized this finding to identify the essential amino acids of EF-TuMp that mediate Fn interactions by generating modified recombinant EF-Tu proteins with amino acid changes corresponding to those of EF-TuMg. Amino acid changes in serine 343, proline 345, and threonine 357 were sufficient to significantly reduce the Fn binding of EF-TuMp. Synthetic peptides corresponding to this region of EF-TuMp (EF-TuMp 340-358) blocked both recombinant EF-TuMp and radiolabeled M. pneumoniae cell binding to Fn. In contrast, EF-TuMg 340-358 peptides exhibited minimal blocking activity, reinforcing the specificity of EF-Tu-Fn interactions as mediators of microbial colonization and tissue tropism.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900. Phone: (210) 567-3939. Fax: (210) 567-6491. E-mail: baseman{at}uthscsa.edu

{triangledown} Published ahead of print on 22 June 2009.

Editor: S. R. Blanke

Infection and Immunity, September 2009, p. 3533-3541, Vol. 77, No. 9
0019-9567/09/$08.00+0     doi:10.1128/IAI.00081-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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