| Function/role | Biochemical activity & directionality | Cofactors/modulators | Complex partners/interactions | Key quantitative data | Key sources with year and URL |
|---|---|---|---|---|---|
| Core nuclease subunit of T4 MR complex (gp47 = Mre11 homolog) | gp47 is the nuclease subunit in the heterotetrameric Mre11-Rad50 complex; activities observed for T4 MR are a Mn2+-dependent ssDNA endonuclease and a Mn2+- and ATP-dependent dsDNA exonuclease with prevailing 3′→5′ polarity on dsDNA (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000010) | Strong dependence on Mn2+ for canonical in vitro nuclease assays; ATP needed mainly for repetitive/processive dsDNA cleavage rather than first-nucleotide removal (pqac-00000000, pqac-00000002) | Forms MR complex with gp46 (Rad50); T4 MR is described as Mre112-Rad502 heterotetramer, with possible higher-order assemblies via Rad50 zinc-hook/coiled coils (pqac-00000010, pqac-00000012, pqac-00000015) | Max dsDNA exonuclease rate ~7.7 nt/s; ~4 nt removed per ATP hydrolyzed (pqac-00000002, pqac-00000012) | Herdendorf et al. 2011, JBC, https://doi.org/10.1074/jbc.m110.178871 ; Teklemariam et al. 2018, Methods Enzymol., https://doi.org/10.1016/bs.mie.2017.12.007 |
| ATPase-coupled DNA end processing | Rad50 ATPase is allosterically stimulated by gp47/Mre11 and DNA; ATP hydrolysis supports translocation/processive nucleotide removal during exonuclease action (pqac-00000002, pqac-00000004, pqac-00000015) | DNA and Mre11 stimulate Rad50 ATPase; ATP/AMP-PNP alter exonuclease behavior; Mre11 dimer interface is functionally coupled to Rad50 ATPase (pqac-00000002, pqac-00000004, pqac-00000015) | gp47-Mre11 activates gp46-Rad50 ATPase through allosteric communication; disruption of Mre11 dimer interface uncouples nuclease from ATPase activation (pqac-00000004, pqac-00000015) | Rad50 alone kcat ~0.15 s^-1; Mre11 + dsDNA increase ATP hydrolysis ~20-fold; Hill coefficient rises from ~1.4 to ~2.4 in MR-DNA complex (pqac-00000002, pqac-00000012) | Herdendorf et al. 2011, JBC, https://doi.org/10.1074/jbc.m110.178871 ; Albrecht et al. 2012, JBC, https://doi.org/10.1074/jbc.m112.392316 |
| Mg2+ vs Mn2+ nuclease mode switching | Under Mg2+ alone, little/no nuclease is detected; with gp32 + UvsY, Mg2+-supported cleavage appears and yields altered products consistent with endonucleolytic processing rather than the standard Mn2+-supported exonuclease profile (pqac-00000000, pqac-00000002, pqac-00000016) | UvsY recombination mediator and gp32 ssDNA-binding protein alter divalent-cation preference and nuclease output; Mn2+ supports canonical MR nuclease directly, Mg2+ requires accessory proteins for robust activity (pqac-00000000, pqac-00000002, pqac-00000007, pqac-00000009) | Functional coupling to gp32 and UvsY links DNA resection to downstream presynaptic filament assembly in T4 HR/RDR (pqac-00000007, pqac-00000009) | In Mg2+ with UvsY/gp32, ~32% of products were 15-25 nt long, versus mostly mononucleotide products in Mn2+-dependent reaction (pqac-00000016) | Herdendorf et al. 2011, JBC, https://doi.org/10.1074/jbc.m110.178871 ; Morrical 2025, EcoSal Plus, https://doi.org/10.1128/ecosalplus.esp-0003-2025 |
| DSB resection and homologous recombination / recombination-dependent replication (RDR) | Current model places gp47/gp46 in the initial DNA-end resection step that generates recombinogenic 3′ ssDNA tails used for UvsX-mediated strand invasion and RDR, although the isolated enzyme shows predominant 3′→5′ dsDNA exonuclease activity in vitro (pqac-00000008, pqac-00000011, pqac-00000012) | Likely coordinated with gp32, UvsY, UvsX, and other T4 HR proteins during infection (pqac-00000008, pqac-00000009, pqac-00000019) | Genetic pathway links gp47/gp46 with genes 32, 59, uvsX, and uvsY in T4 recombination and repair (pqac-00000019) | In vivo DSB repair/replication reaction is reported as absolutely dependent on products of genes including 46; repaired products formed long plasmid concatemers and often exchanged flanking DNA (pqac-00000019) | Liu & Morrical 2010, Virol. J., https://doi.org/10.1186/1743-422x-7-357 ; George & Kreuzer 1996, Genetics, https://doi.org/10.1093/genetics/143.4.1507 ; Herdendorf et al. 2011, JBC, https://doi.org/10.1074/jbc.m110.178871 |
| Host genome degradation during T4 infection | T4 MR complex is also assigned a noncanonical role in degradation/processing of host genomic DNA to supply deoxynucleotides for phage DNA synthesis (pqac-00000010, pqac-00000022) | Same MR machinery; comparatively rapid ATPase/exonuclease behavior has been proposed to relate to this physiological role (pqac-00000022) | gp47 acts with gp46/Rad50 as the phage MR complex during infection (pqac-00000010, pqac-00000022) | No direct numeric in vivo host-degradation rate extracted here; review/chapter sources emphasize host DNA degradation as a major physiological function (pqac-00000010, pqac-00000022) | Teklemariam et al. 2018, Methods Enzymol., https://doi.org/10.1016/bs.mie.2017.12.007 |
| Structure-function annotation of gp47 itself | gp47 is consistently annotated as the T4 Mre11 ortholog and structural models are based on archaeal Mre11 bound to Mn2+ and DNA; Mre11 dimer interface regulates at least two exonuclease states (pqac-00000007, pqac-00000009, pqac-00000015) | Metal-dependent phosphodiesterase core inferred from Mre11-family conservation; activity state influenced by ATP/DNA through Rad50 and by Mre11 dimer conformation (pqac-00000004, pqac-00000015) | Interacts with gp46/Rad50, dsDNA, gp32, and UvsY; Mre11 dimer interface is critical for productive assembly/translocation balance (pqac-00000004, pqac-00000015) | L101D Mre11 mutant retains Rad50/dsDNA binding but reduces processive dsDNA exonuclease ~10-fold under processive conditions (pqac-00000004) | Albrecht et al. 2012, JBC, https://doi.org/10.1074/jbc.m112.392316 ; Morrical 2025, EcoSal Plus, https://doi.org/10.1128/ecosalplus.esp-0003-2025 |


*Table: This table compacts the main functional annotation for bacteriophage T4 gp47/Mre11, emphasizing its nuclease role in the gp46-gp47 MR complex, metal/cofactor dependence, pathway context, and quantitative biochemical data. It is useful as a quick evidence map linking function, mechanism, and sources.*