Amino acid changes in elongation factor Tu of Mycoplasma pneumoniae and Mycoplasma genitalium influence fibronectin binding.
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-Tu(Mp)) 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-Tu(Mg)), in spite of sharing 96% identity with EF-Tu(Mp), does not bind Fn. We utilized this finding to identify the essential amino acids of EF-Tu(Mp) that mediate Fn interactions by generating modified recombinant EF-Tu proteins with amino acid changes corresponding to those of EF-Tu(Mg). Amino acid changes in serine 343, proline 345, and threonine 357 were sufficient to significantly reduce the Fn binding of EF-Tu(Mp). Synthetic peptides corresponding to this region of EF-Tu(Mp) (EF-Tu(Mp) 340-358) blocked both recombinant EF-Tu(Mp) and radiolabeled M. pneumoniae cell binding to Fn. In contrast, EF-Tu(Mg) 340-358 peptides exhibited minimal blocking activity, reinforcing the specificity of EF-Tu-Fn interactions as mediators of microbial colonization and tissue tropism.
Balasubramanian
Sowmya
S
Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA.
Kannan
T R
TR
Hart
P John
PJ
Baseman
Joel B
JB
D000595:Amino Acid Sequence; D005353:Fibronectins / Q000378:metabolism*; D008958:Models, Molecular; D045704:Mycoplasma genitalium / Q000378:metabolism*; D009177:Mycoplasma pneumoniae / Q000378:metabolism*; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D018523:Tropism
D005353:Fibronectins; D010444:Peptide Elongation Factor Tu