helicaseandRNaseDlike

helicaseandRNaseDlike is a putative multi-domain protein designation used in comparative genomics to describe proteins that combine a helicase-like domain with a DEDD-family RNase D-like catalytic domain. These proteins have been identified in genome annotations across diverse bacteria and archaea, but remain poorly characterized in terms of function and physiology. The term is descriptive rather than evidence-based for a defined, experimentally validated protein family.

The proposed architecture typically features an N-terminal helicase-like region resembling SF2 RNA helicases, containing motifs associated with NTP binding and hydrolysis, such as a Walker A motif. The C-terminal region aligns with RNase D-like exoribonuclease domains, which are associated with 3′–5′ RNA degradation and metal-dependent catalysis. The co-occurrence of these domains in a single polypeptide suggests a potential coupling of RNA remodeling and processing activities, though the exact structural arrangement and active site coordination remain to be experimentally confirmed.

Possible functions for helicaseandRNaseDlike include involvement in RNA maturation, quality control, or decay pathways where structured RNA substrates require unwinding before exonuclease processing. If active, the protein could coordinate substrate remodeling with 3′ end trimming, potentially in response to cellular RNA turnover demands or stress conditions. However, substrate specificity, directionality, cofactor requirements, and cellular localization are currently unknown.

Research status for helicaseandRNaseDlike is preliminary, with no definitive biochemical characterization widely cited. Future work would aim to validate activity for both domains, define substrate scope, determine partner factors, and clarify evolutionary origins and distribution across lineages.