Nucleases Nucleases have been reported as potential pathogenicity factors in other organisms as well [44]. Ureaplasmas belong to a group of organisms that import nucleotides for DNA and RNA synthesis. Therefore it is likely that they have secreted or surface bound nucleases that may also play a role in pathogenicity. We identified 15 potential nucleases, of which two had a predicted signal peptide, and thus are likely to be secreted or surface bound. These nucleases may be an interesting target for further studies of their potential involvement in pathogenicity. Putative O-sialoglycoprotein peptidase Eleven of the 14 ureaplasma serovars selleck screening library contained a
gene annotated as an O-sialoglycoprotein endopeptidase (UPA3_0428 [GenBank: ACA33260]). UUR serovars 2, 8, and 10 did not contain an ortholog ACP-196 of this gene. Because all three of these genomes are complete (no gaps in the genome sequence), we can be sure the gene is absent. This enzyme
has been shown to cleave human erythrocyte glycophorin A in other bacteria [45]. The same study showed that the specificity of this peptidase is limited to O- glycosylated membrane glycoproteins, and it cannot cleave N-glycosylated proteins. Abdullah et al. [45] suggest that the potential targets of this enzyme in the host are sialoglycoproteins of the mucosal epithelial cells or on the cell surfaces of macrophages. In fact the O-sialoglycoprotein peptidase of Mannheimia haemolytica ABT-737 molecular weight cleaves from the surface of the human cell line KGla the CD43-leukosialin and other human O- sialoprotein antigens like the progenitor cell-restricted antigen CD34, the hyaluronate receptor CD44, and the leukocyte common antigen tyrosine phosphatase CD45 class FER of molecules [45]. If the ureaplasma putative O-sialoglycoprotein
peptidase is capable of cleaving such targets, this could be a mechanism for evasion of the host immune system, colonization of the host, and eventually establishment of an infection. In M. haemolytica isolates the presence of this gene is associated with the capacity of the bacteria to cause pneumonia in calves [45]. Macrophage infection mutant protein, MimD UUR2 contained a gene annotated mimD (UUR2_0526 [GenBank: ZP_03771352]) standing for macrophage interaction mutant D. Mycobacterium marinum is a fish, amphibian, and human pathogen that may be able to survive and replicate in macrophages. A study of macrophage infection D. marinum mutants identified a mutation in a hypothetical protein that resulted in this phenotype [46]. The exact function of this gene in interactions with macrophages is not yet defined; however the ureaplasma annotated mimD gene (183 aa) had 40% identity and 68% similarity over 179 aa long alignment with the M. marinum mimD gene (731 aa). Further characterization of MimD in other systems and possibly ureaplasma would be interesting.