GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

file:BPT4/arn/arn-deep-research-falcon.md

Deep research summary for Bacteriophage T4 arn

Arn is a non-catalytic protein-based inhibitor/DNA mimic rather than a catalytic nuclease.

"rather than viewing Arn primarily as a catalytic nuclease, Arn is discussed as part of a set of **protein-based inhibitors/mimics** that subvert restriction systems."
Like T7 Ocr, T4 Arn functions as a DNA-mimic protein whose negatively charged surface mimics B-form DNA to inhibit host restriction systems.

"T7 Ocr is described as structurally mimicking one helical turn of B-form DNA with a negatively charged surface resembling the DNA phosphate backbone, enabling inhibition of restriction and even BREX. The same review explicitly states that “**Similar to Ocr, the coliphage T4 protein Arn … uses the same principle**,” placing Arn in the modern DNA-mimic anti-restriction conceptual framework."

file:BPT4/arn/arn-uniprot.txt

UniProtKB entry P39510 (ARN_BPT4)

Arn inhibits the host restriction-modification system, including the host McrA endonuclease that targets 5-methyl- and 5-hydroxymethylcytosine DNA.

"Pays a role in the inhibition of the host restriction-modification system. Strongly inhibits the host mcrA endonuclease that cleaves 5-methyl and 5-hydroxymethylcytosines at the specific DNA sequence C(me)CGG. {ECO:0000269|PubMed:380146, ECO:0000269|PubMed:768783}."
Crystal structure of T4 Arn has been determined at 1.90 A resolution (PDB 3WX4) and belongs to the DM_Arn DNA-mimic family (PF22134).

"PDB; 3WX4; X-ray; 1.90 A; A=1-92."