Abstract
NrnC from Agrobacterium tumefaciens (At_NrnC, UniProt accession number A9CG28) is a nuclease containing a single DEDDy domain. Here, we determined the structures of both the apo and metal-ion-bound forms of At_NrnC. Although the overall structure of the At_NrnC protomer is similar to that of the RNase D exonuclease domain, nuclease assays unexpectedly revealed that At_NrnC possesses remarkably different substrate specificity. In contrast to RNase D, which degrades both single-stranded RNA (ssRNA) and double-stranded RNA (dsRNA), At_NrnC hydrolyses ssRNA, single-stranded DNA (ssDNA), and double-stranded DNA (dsDNA) with high efficiency but does not degrade dsRNA. Crystal packing analysis and biochemical data indicated that At_NrnC forms an octameric hollow cylindrical structure that allows ssRNA, ssDNA, and dsDNA, but not dsRNA, to enter the central tunnel where the multiple active sites perform hydrolysis. This novel structural feature confers a high processivity and is responsible for the preference of At_NrnC for longer dsDNA substrates.
Highlights
Nucleases are a highly diverse group of enzymes that cleave the phosphodiester bonds of nucleic acids
Most of the studies in this field focused on the fulllength RNase D, and it remains uncertain whether the truncated RNase D-like proteins function in a similar manner
DEDD exonucleases participate in numerous nucleic acid metabolism pathways and are widely distributed in bacteria
Summary
Nucleases are a highly diverse group of enzymes that cleave the phosphodiester bonds of nucleic acids. For these proteins, the correlation between catalytic mechanism and biological function is weak (Yang, 2011). A single bacterial cell often contains dozens of nucleases, which play important roles in numerous metabolic pathways, where one enzyme may degrade multiple substrates and one substrate may be cleaved by multiple enzymes. These features render it challenging to identify the natural substrate(s) and biological role of a particular nuclease. RNase D from Escherichia coli (Ec_RND) contains two helicase and RNase D C-terminal (HRDC) domains at its C-terminus
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
