DNA beta-glucosyltransferase (BGT; EC 2.4.1.27) is a monomeric, 351-amino-acid DNA-modifying glycosyltransferase of bacteriophage T4 and the structural prototype of the GT-B glycosyltransferase fold superfamily. BGT catalyzes the inverting transfer of a beta-D-glucosyl residue from UDP-alpha-D-glucose onto 5-hydroxymethylcytosine (5hmC) bases in double-stranded T4 DNA via an extrahelical base-flipping mechanism using Asp100 as the catalytic base. By converting approximately 30% of genomic 5hmC residues to beta-glucosyl-5hmC (complementing alpha-glucosylation by Agt), BGT shields the phage genome from T4's own cytosine-specific nucleases and from host restriction-modification and CRISPR-Cas defense systems.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0016740 transferase activity | IEA GO_REF:0000043 | MODIFY | Summary: Broad keyword-derived annotation; BGT specifically catalyzes DNA beta-glucosyltransferase activity (GO:0033821). Reason: While BGT is a transferase, GO:0016740 is too general because the exact reaction is captured by the descendant term GO:0033821 (DNA beta-glucosyltransferase activity, EC 2.4.1.27), which is already annotated to this gene. Proposed replacements: DNA beta-glucosyltransferase activity Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md **BGT (bgt; UniProt P04547)** is a **DNA-modifying glycosyltransferase** that transfers glucose from **UDP-glucose** onto **5hmC residues in double-stranded DNA**, producing **Ξ²-glucosyl-5hmC** in the phage genome. file:BPT4/bgt/bgt-uniprot.txt Reaction=Transfers a beta-D-glucosyl residue from UDP-alpha-D-glucose to a hydroxymethylcytosine residue in DNA.; EC=2.4.1.27; |
| GO:0016757 glycosyltransferase activity | IEA GO_REF:0000043 | MODIFY | Summary: Correct parent term but less specific than GO:0033821 (DNA beta-glucosyltransferase activity). Reason: BGT is a GT-B glycosyltransferase, but the specific descendant term GO:0033821 (DNA beta-glucosyltransferase activity) is experimentally established and already present on the gene. Proposed replacements: DNA beta-glucosyltransferase activity Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md **BGT (bgt; UniProt P04547)** is a **DNA-modifying glycosyltransferase** that transfers glucose from **UDP-glucose** onto **5hmC residues in double-stranded DNA**, producing **Ξ²-glucosyl-5hmC** in the phage genome. file:BPT4/bgt/bgt-uniprot.txt Reaction=Transfers a beta-D-glucosyl residue from UDP-alpha-D-glucose to a hydroxymethylcytosine residue in DNA.; EC=2.4.1.27; |
| GO:0033821 DNA beta-glucosyltransferase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Accurately captures the primary catalytic activity of BGT (EC 2.4.1.27). Reason: Extensive biochemical and crystallographic studies establish that BGT transfers a beta-D-glucosyl moiety from UDP-glucose to 5-hydroxymethylcytosine residues in double-stranded DNA. Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md **BGT (bgt; UniProt P04547)** is a **DNA-modifying glycosyltransferase** that transfers glucose from **UDP-glucose** onto **5hmC residues in double-stranded DNA**, producing **Ξ²-glucosyl-5hmC** in the phage genome. file:BPT4/bgt/bgt-uniprot.txt Reaction=Transfers a beta-D-glucosyl residue from UDP-alpha-D-glucose to a hydroxymethylcytosine residue in DNA.; EC=2.4.1.27; |
| GO:0052031 symbiont-mediated perturbation of host defense response | IEA GO_REF:0000043 | MODIFY | Summary: Broad parent process term that should be refined to the specific descendant GO:0099018 (symbiont-mediated evasion of host restriction-modification system). Reason: Beta-glucosylation of 5hmC in T4 DNA specifically protects the phage genome from host restriction-modification endonucleases, captured by the descendant term GO:0099018 already annotated to the gene. Proposed replacements: symbiont-mediated evasion of host restriction-modification system Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md Glucosylation of 5hmC is described as part of a **phage DNA protection system**, helping prevent cleavage by host nucleases and restriction endonucleases file:BPT4/bgt/bgt-uniprot.txt The glc-HMC modification protects the phage genome against its own nucleases and the host restriction endonuclease system (PubMed:22229759). |
| GO:0052170 symbiont-mediated suppression of host innate immune response | IEA GO_REF:0000043 | MODIFY | Summary: General keyword-mapped term that should be refined to GO:0099018 (symbiont-mediated evasion of host restriction-modification system). Reason: The innate host defense system evaded by BGT-mediated DNA beta-glucosylation is the host restriction-modification system, captured by the descendant term GO:0099018 already present on the gene. Proposed replacements: symbiont-mediated evasion of host restriction-modification system Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md Glucosylation of 5hmC is described as part of a **phage DNA protection system**, helping prevent cleavage by host nucleases and restriction endonucleases file:BPT4/bgt/bgt-uniprot.txt The glc-HMC modification protects the phage genome against its own nucleases and the host restriction endonuclease system (PubMed:22229759). |
| GO:0099018 symbiont-mediated evasion of host restriction-modification system | IEA GO_REF:0000120 | ACCEPT | Summary: Core biological role of BGT-catalyzed DNA beta-glucosylation in protecting T4 DNA from host restriction endonucleases. Reason: Beta-glucosylation of 5hmC residues in T4 DNA prevents cleavage by host restriction-modification systems. Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md Glucosylation of 5hmC is described as part of a **phage DNA protection system**, helping prevent cleavage by host nucleases and restriction endonucleases file:BPT4/bgt/bgt-uniprot.txt The glc-HMC modification protects the phage genome against its own nucleases and the host restriction endonuclease system (PubMed:22229759). |
| GO:0006304 DNA modification | IEA GO_REF:0000041 | ACCEPT | Summary: Directly describes the covalent beta-glucosylation of 5hmC residues in T4 genomic DNA. Reason: BGT modifies 5-hydroxymethylcytosine bases in double-stranded T4 DNA to yield beta-glucosyl-5-hydroxymethylcytosine. Supporting Evidence: file:BPT4/bgt/bgt-deep-research-falcon.md **BGT (bgt; UniProt P04547)** is a **DNA-modifying glycosyltransferase** that transfers glucose from **UDP-glucose** onto **5hmC residues in double-stranded DNA**, producing **Ξ²-glucosyl-5hmC** in the phage genome. file:BPT4/bgt/bgt-uniprot.txt Catalyzes the transfer of glucose from uridine diphosphoglucose to 5-hydroxymethyl cytosine of T4 DNA to yield glucosyl 5-hydroxymethyl cytosine (glc-HMC) (PubMed:22229759). |
| GO:0033821 DNA beta-glucosyltransferase activity | IDA PMID:6078540 On the specificity of bacteriophage-induced hydroxymethylcyt... | ACCEPT | Summary: Direct experimental annotation for BGT's enzymatic activity on 5hmC-containing DNA. Reason: de Waard et al. (1967) and subsequent structural and mechanistic studies directly establish that BGT is the T4-induced hydroxymethylcytosine beta-glucosyltransferase. Supporting Evidence: PMID:6078540 On the specificity of bacteriophage-induced hydroxymethylcytosine glucosyltransferases. II. Specificities of hydroxymethylcytosine alphaand beta-glucosyltransferases induced by bacteriophage T4. file:BPT4/bgt/bgt-deep-research-falcon.md **BGT (bgt; UniProt P04547)** is a **DNA-modifying glycosyltransferase** that transfers glucose from **UDP-glucose** onto **5hmC residues in double-stranded DNA**, producing **Ξ²-glucosyl-5hmC** in the phage genome. |
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Download this section (compressed HTML)Q: Unlike AGT, which binds the gp45 sliding clamp, does BGT interact with any replisome component in vivo or does it act distributively on remaining unglucosylated 5hmC sites after replication fork passage?
Q: What local DNA structural features govern BGT's preference for the ~30% of genomic 5hmC sites that remain unglucosylated by AGT?
Experiment: Perform high-throughput base-flipping fluorescence kinetics (using 2-aminopurine-substituted 5hmC duplexes across all dinucleotide/trinucleotide contexts) to quantitatively explain the 70:30 genomic partitioning between AGT and BGT.
Experiment: Test whether BGT co-purifies or cross-links with T4 replisome proteins in infected E. coli cells using proximity labeling (BioID/TurboID).
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