The pssP null mutant was not complemented and the reason for failure might have been the uninduced expression of pssP used for complementation. The C-terminal cytoplasmic domain of PssP is characterized by the presence of an ATP-binding cassette domain. However, no tyrosine-rich motif, a hypothetic target for the phosphorylating/ dephosphorylating activity,Sulbactam sodium is present in this domain, excluding autophosphorylating activity similar to that of S. meliloti ExoP and E. coli Wzc. PssP2 is also similar to bacterial kinases involved in polysaccharide production, but it is devoid of any specific motifs and appeared not to be phosphorylated. Dissection of the functions of other genes in the Pss-II regions seems to be reasonable to clarify the functional importance of abundance of homologues implicated in polysaccharide synthesis. It cannot be excluded that the genes in the Pss-II region are important for modifications of the EPS HMW:LMW ratio in the plant tissue or under unconsidered environmental conditions. Toxin-antitoxin systems are small genetic modules widely distributed in bacteria and archaea that are comprised of a pair of genes encoding a stable toxin and an unstable antitoxin capable of inhibiting toxin activity. In contrast to bacteriocins and toxins from contact-dependent inhibition systems, TA toxins are not secreted and inhibit cell growth by targeting key molecules in Gentamycin Sulfate essential cellular processes such as DNA replication, mRNA stability or protein, cell-wall or ATP biosynthesis. TA systems were first discovered as systems that contribute to plasmid maintenance by a phenomenon denoted as ‘‘postsegregational killing’’ or ‘‘addiction’’. When a plasmid encoding a TA system is lost from a cell, the toxin is released from the existing TA complex as the unstable antitoxin decays, resulting in cell growth inhibition and eventually death. In addition to plasmids, TA systems are also found in bacterial chromosomes, particularly in free-living prokaryotic cells, but their function is not well understood. Although chromosomal TA systems are not essential for normal cell growth, it is believed that they play key roles in stress response, persister phenotype and stabilization of horizontally acquired genetic elements.