Ribonuclease H-like domain
IPR013520
Definition
This entry includes a variety of exonuclease proteins, such as Oligoribonuclease, ribonuclease T PMID:8506149 and the epsilon subunit of DNA polymerase III. Ribonuclease T ([ec:3.1.13]) is an enzyme found so far only in gamma-subdivision proteobacteria such as Escherichia coli and Xylella fastidiosa. Ribonuclease T is homologous to the DNA polymerase III alpha chain. It can liberate AMP from the common C-C-A terminus of uncharged tRNA. It appears also to be involved in RNA maturation. It also acts as a 3' to 5' single-strand DNA-specific exonuclease; it is distinctive for its ability to remove residues near a double-stranded stem. Ribonuclease T is a high copy suppressor in E. coli of a UV-repair defect caused by deletion of three other single-stranded DNA exonucleases PMID:9857048. Oligoribonuclease (Orn) is an essential 3'->5' exoribonuclease in Escherichia coli and other bacteria, specialising in the degradation of small oligoribonucleotides (2-5 nucleotides) to mononucleotides during mRNA decay. It ensures complete RNA turnover by hydrolysing these short RNA fragments, which accumulate lethally in its absence, disrupting cellular viability. Beyond mRNA processing, Orn plays a critical role in cyclic diguanylate (c-di-GMP) signalling by degrading the intermediate 5'-phosphoguanylyl-(3',5')-guanosine (pGpG), preventing its accumulation and subsequent inhibition of c-di-GMP phosphodiesterases. This activity regulates biofilm formation and virulence in pathogens like Pseudomonas aeruginosa. Structurally conserved across domains of life, Orn operates processively via a manganese-dependent mechanism, preferring substrates with free 3'-hydroxyl groups and exhibiting inverse activity dependence on oligomer length. Its dual role in RNA metabolism and signalling underscores its importance in maintaining cellular homeostasis [[cite:PMID:10200269], [cite:PMID:26305928], [cite:PMID:9573169]].
14 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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