An RNase that has 5'-3' exonuclease and possibly endoonuclease activity. Degrades 5'-monophosphorylated ssRNA and dsRNA, considerably more active on ssRNA. Association with RhpA significantly increases the dsRNase activity. Stimulates ATPase activity of RNA helicase RhpA. Involved in stabilization of mRNA but apparently not rRNA. Binds up to 2 Zn(2+) ions per subunit. It is not clear if Zn(2+) or Mg(2+) is physiologically important. Homodimer (By similarity). Interacts with RNA helicase RphA, might be a member of a minimal RNA degradosome complex. The RNaseJ-RhpA complex co-localizes with 70S ribosomes and polysomes; remains associated with ribosomes in the absence of RhpA. The first 132 residues are not conserved outside of Helicobacter. Important for protein stability; a depletion mutant expressing this truncated protein accumulates more ureI mRNA than a depletion mutant able to express low levels of wild-type protein. The trunated protein still stimulates ATPase activity of RNA helicase RhpA. Essential, it cannot be disrupted. Depletion experiments show only slightly retarded growth with an increase in levels of at least 1 mRNA (ureI). RhpA remains associated with the ribosomes and polysomes. Belongs to the metallo-beta-lactamase superfamily. RNA-metabolizing metallo-beta-lactamase-like family. Bacterial RNase J subfamily.