HAMAP rule MF_04148

Accession	MF_04148
Dates	18-FEB-2020 (Created) 19-NOV-2022 (Last updated, Version 5)

Name	TERL_BPP22

Scope

Viruses

Template

P26745 (TERL_BPP22)

Triggered by

HAMAP; MF_04148 (Get profile general information and statistics)

Identifier

TERL

Protein name

RecName: Full=Terminase, large subunit; AltName: Full=DNA-packaging protein gp2; Includes: RecName: Full=Endonuclease; EC 3.1.21.-; Includes: RecName: Full=ATPase; EC 3.6.4.-;

Function

The terminase large subunit acts as an ATP driven molecular motor necessary for viral DNA translocation into empty capsids and as an endonuclease that cuts the viral genome to initiate and to end a packaging reaction. The terminase lies at a unique vertex of the procapsid and is composed of two subunits, a small terminase subunit involved in viral DNA recognition (packaging sequence), and a large terminase subunit possessing endonucleolytic and ATPase activities. Both terminase subunits heterooligomerize and are docked on the portal protein to form the packaging machine. The terminase large subunit exhibits endonuclease activity and cleaves the viral genome concatemer once the capsid is full (headful packaging). Once the capsid is packaged with the DNA, the terminase complex is substituted by the tail.

Function

The terminase large subunit acts as an ATP driven molecular motor necessary for viral DNA translocation into empty capsids and as an endonuclease that cuts the viral genome to initiate and to end a packaging reaction. The terminase lies at a unique vertex of the procapsid and is composed of two subunits, a small terminase subunit involved in viral DNA recognition (packaging sequence), and a large terminase subunit possessing endonucleolytic and ATPase activities. Both terminase subunits heterooligomerize and are docked on the portal protein to form the packaging machine. Once the capsid is packaged with the DNA, the terminase cleaves the viral genome concatemer and is substituted by the tail.

Cofactor

Mg(2+) Note: Nuclease activity probably requires 2 Mg(2+) ions per subunit

Subunit	Interacts with the terminase small subunit; the active complex is composed of a monomer of the terminase large subunit and a nonamer ring of terminase small subunits. Interacts with the portal protein; this interaction allows the packaging of viral DNA.
Domain	The ATPase region is in the N-terminus, whereas the nuclease region is in the C-terminus.
Similarity	Belongs to the Lederbergvirus large terminase family.

ATP-binding
Endonuclease
Hydrolase
Late protein
Nuclease
Nucleotide-binding
Viral genome packaging
Viral release from host cell

Magnesium
Metal-binding

GO:0098009; Cellular component: viral terminase, large subunit.
GO:0004519; Molecular function: endonuclease activity.
GO:0046872; Molecular function: metal ion binding.
GO:0004518; Molecular function: nuclease activity.
GO:0051276; Biological process: chromosome organization.
GO:0019073; Biological process: viral DNA genome packaging.

Pfam	PF03237; Terminase_6; 1;
	PF17289; Terminase_6C; 1;

From: TERL_BPP22 (P26745)

Key

From

To

Description

Tag

Condition

FTGroup

REGION

1

58

Interaction with the terminase small subunit

REGION

1

286

ATPase activity

REGION

312

482

Nuclease activity

MOTIF		60		67		Walker A motif				[ACT]-[AG]-N-[QR]-[CILV]-G-K-[ST]
MOTIF		199		204		Walker B motif				[FGILVWY]-[FIV]-[WH]-[FILM]-D-E
ACT_SITE		204		204		For ATPase activity				E
BINDING		321		321		/ligand="Mg(2+)" /ligand_id="ChEBI:CHEBI:18420" /ligand_note="catalytic; for nuclease activity				D		1
BINDING		459		459		/ligand="Mg(2+)" /ligand_id="ChEBI:CHEBI:18420" /ligand_note="catalytic; for nuclease activity				D		1

Size range	400-530 amino acids
Related rules	None
Fusion	None

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