Displays transglutaminase activity (TGase) in vitro. Plays a critical role in the viability of P.aeruginosa. Might contribute to an essential function linked to the cell wall. L-glutaminyl-[protein] + L-lysyl-[protein] = [protein]-L-lysyl-N(6)-5-L-glutamyl-[protein] + NH4(+) Is expressed in both exponential and stationary phases of growth. Appears to be part of an operon together with PA2874 and PA2875. The transglutaminase activity is contained within the periplasmic domain (180-544). Disruption experiments show that tgpA is essential. Unlike Guinea pig TGase, TGase activity is not affected by EDTA addition, suggesting that TGase activity is Ca(2+)-independent, similar to members of the bacterial transglutaminase family. Belongs to the transglutaminase-like superfamily.