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tRNA threonylcarbamoyl adenosine modification protein TsaD This model represents bacterial members of a protein family that is widely distributed. In a few pathogenic species, the protein is exported in a way that may represent an exceptional secondary function. This model plus companion (archaeal) model TIGR03722 together span the prokaryotic member sequences of TIGR00329, a protein family that appears universal in life, and whose broad function is unknown. A member of TIGR03722 has been characterized as a DNA-binding protein with apurinic endopeptidase activity. In contrast, the rare characterized members of the present family show O-sialoglycoprotein endopeptidase (EC. 3.4.24.57) activity after export. These include glycoprotease (gcp) from Pasteurella haemolytica A1 and a cohemolysin from Riemerella anatipestifer (GB|AAG39646.1). The member from Staphylococcus aureus is essential and is related to cell wall dynamics and the modulation of autolysis, but members are also found in the Mycoplasmas (which lack a cell wall). A reasonable hypothesis is that virulence-related activities after export are secondary to a bacterial domain-wide unknown function. [Protein synthesis, tRNA and rRNA base modification]
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