The amount of chains correlated with the level of protein production, but the length of O-antigen chains was dependent on a specific amino acid residue in a coiled coil domain. Different amino acids may influence oligomerization and stability of the oligomers. Papadopoulos and Morona noted that chain length was related to the stability of Wzz interactions;D-glutamine they described a positive correlation between dimer stability and the production of longer chain lengths. Changes in the oligomerization ability of mutated proteins may also be the case for the pssP and pssP2 mutants. The PssP variants were not able to oligomerize and the mutants produced more LMW EPS. PssP2 also oligomerizes, thus secondary coiled-coils disrupted in the mutant might have affected its oligomerization/interaction properties. It seems reasonable that besides specific amino acid residues, any significant distortion of structures of Pss proteins may influence their interaction properties and thus the overall property of polymerization of EPS. Several mutated Wzz proteins were undetectable via Western blotting but still produced a regulated chain length. PCP proteins appear to be expressed at a higher level than Wzy polymerases,Perindopril Erbumine nevertheless still low. The promoter identified upstream pssP2 is weak and the pssP2 transcription is probably driven by a promoter preceding pssY with the medium activity comparable with the promoter of pssP. pssP2 lacks a strong RBS and has several rare codons in the 59-end that may further support the low abundance of PssP2 in the RtTA1. It was shown that Wzz1 responsible for LMW polymers in P. aeruginosa could complement the phenotype even with the uninduced expression, while Wzz2 required induced expression for complementation. The two proteins: PssP and PssP2 may have significantly different abundances in the cell, which would correlate with their functions and the possibly different mode of interaction with PssT. Data concerning promoter activity correlate with the phenotypes of pssP2 and pssP mutants. The pssP2::pKP2 mutant was complemented via uninduced expression, which suggests that the level of protein produced without induction was sufficient for the cell to restore the function.