Nu1 (P03707) - Terminase small subunit (gpNu1)
Summary
- Gene symbol:
Nu1
- UniProt ID:
P03707
- Organism: Escherichia phage lambda (
NCBITaxon:2681611)
- Protein: Terminase small subunit (
gpNu1, 181 aa)
Biological Function
- Forms the small regulatory/DNA-recognition subunit (
gpNu1) of the bacteriophage lambda terminase holoenzyme, which assembles as a heterotrimeric protomer ($\mathrm{gpA_1 \cdot gpNu1_2}$, 114.2 kDa) capable of further associating into a homogeneous tetramer of heterotrimers PMID:15755448.
- Recognizes and binds the three R elements (R3, R2, R1) within the
cosB sub-site of the cohesive end site (cos) via an N-terminal winged helix-turn-helix (wHTH) dimerization/DNA-binding domain, and acts cooperatively with Escherichia coli integration host factor (IHF) to strongly bend cos DNA and position the large subunit (gpA) at cosN for site-specific nicking and packaging initiation PMID:16618107.
- Contains a low-affinity, DNA-stimulated ATPase active site that regulates viral DNA binding and
cos cleavage dynamics [PMID:2965248, PMID:8611586].
Curation Decisions
- ACCEPT:
GO:0044374 (sequence-specific DNA binding, bending, IDA PMID:16618107)GO:0016887 (ATP hydrolysis activity, IDA PMID:2965248, PMID:8611586, IEA GO_REF:0000116)GO:0005524 (ATP binding, IEA GO_REF:0000043)GO:0019073 (viral DNA genome packaging, IDA PMID:15755448)GO:0097710 (viral terminase, small subunit, IDA PMID:15755448)GO:0030430 (host cell cytoplasm, IEA GO_REF:0000044)- MODIFY:
GO:0000166 (nucleotide binding) -> GO:0005524 (ATP binding)GO:0003677 (DNA binding) -> GO:0044374 (sequence-specific DNA binding, bending)GO:0016787 (hydrolase activity) -> GO:0016887 (ATP hydrolysis activity)