Toxic component of a type I toxin-antitoxin (TA) system. Overexpression leads to cell stasis and a decrease in colony-forming units (PubMed:20156992). Probably repressed by cognate small RNA orzP. Base pairing occurs between 18 bases in the 5' UTR of zorP mRNA and the 5' end of OrzP sRNA (Probable). Expressed during exponential growth in rich medium and at lower levels in exponential and stationary phase in minimal medium (zorO mRNA cannot be distinguished from zorP mRNA by these assays as they are practically identical).