Is able to cleave peptidoglycan. Increased expression in vivo during human sepsis. Highly expressed under biofilm conditions after 8 hours of growth. Positively regulated by SarA and the two-component system YycFG. Also positively regulated by the two-component sensor-regulator SrrAB under aerated conditions. More protein is secreted in a secG or double secG/secY2 mutant (at protein level). Up-regulation of ssaA and sceD. Its inactivation shows no clumping and results in an apparent increased degree of cell separation which could be due to the up-regulation of sceD. Inactivation of both isaA and sceD genes results in a high degree of clumping and the double mutant is also attenuated for virulence. Belongs to the transglycosylase family. IsaA subfamily.