infB

Gene Description

infB (PA4744) encodes translation initiation factor IF-2, a translational GTPase of the TRAFAC classic translation factor family. IF-2 binds the initiator tRNA, promotes its placement on the 30S ribosomal subunit and hydrolyses GTP during joining of the 50S subunit to form the 70S initiation complex. P. aeruginosa can initiate protein synthesis with either formylated or unformylated initiator Met-tRNAfMet, and its IF-2 is required for the formylation-independent route. This capacity maps to the charge of the cleft that binds the amino end of the aminoacyl group: lowering its positive potential lets E. coli IF-2 accept Met-tRNAfMet, and raising it in P. aeruginosa IF-2 abolishes formylation-independent initiation. The protein is cytoplasmic.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0003743 translation initiation factor activity	IBA GO_REF:0000033	ACCEPT	Summary: IBA from PTN001897651, seeded by E. coli IF2 (IDA), yeast FUN12 and IFM1 (IDA), human eIF5B (IDA), S. pombe mti2 (EXP) and others. Reason: Core molecular function of IF-2, well supported across the clade. Supporting Evidence: PMID:15385567 Here we show that the Pseudomonas aeruginosa initiation factor IF-2 is required for formylation-independent protein initiation in P. aeruginosa
GO:0003743 translation initiation factor activity	IEA GO_REF:0000120	ACCEPT	Summary: InterPro/UniRule mapping for the IF-2 family. Reason: Consistent with the IBA row and HAMAP family membership. Supporting Evidence: file:PSEAE/infB/infB-uniprot.txt One of the essential components for the initiation of protein synthesis.
GO:0003924 GTPase activity	IEA GO_REF:0000120	ACCEPT	Summary: IF-2 is a translational GTPase; GTP hydrolysis accompanies 70S complex formation. Reason: Intrinsic catalytic activity of the tr-type G domain, part of the core mechanism. Supporting Evidence: file:PSEAE/infB/infB-uniprot.txt Also involved in the hydrolysis of GTP during the formation of the 70S ribosomal complex.
GO:0005525 GTP binding	IEA GO_REF:0000002	ACCEPT	Summary: G1-G5 motifs of the tr-type G domain. Reason: GTP binding is required for the GTPase cycle of IF-2. Supporting Evidence: file:PSEAE/infB/infB-uniprot.txt Belongs to the TRAFAC class translation factor GTPase
GO:0005737 cytoplasm	IBA GO_REF:0000033	TOO GENERAL	Summary: IBA at the broad PTN001897651 node (bacterial IF2, mitochondrial and chloroplast IF2, eIF5B); cytoplasm is the right common level there. For PA4744, the gene also carries the more specific cytosol IBA. Reason: True for a bacterial IF-2, but entailed by GO:0005829 cytosol (part_of cytoplasm), accepted below via the E. coli IF2 IBA. The node-level claim is not disputed.
GO:0005737 cytoplasm	IEA GO_REF:0000120	TOO GENERAL	Summary: UniRule subcellular location. Reason: Same claim as the IBA row; entailed by the accepted cytosol row.
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: IBA from PTN000562019 seeded by E. coli IF2 (IDA cytosol). Reason: Bacterial IF-2 acts on cytosolic ribosomes; the seed has direct evidence.
GO:0006413 translational initiation	IBA GO_REF:0000033	ACCEPT	Summary: IBA from PTN001897651. Seeds include the PseudoCAP IMP on Q9HV55 itself (expected, not circular) and independent IDA/EXP/IMP seeds from E. coli IF2, yeast FUN12, S. pombe mti2 and mammalian MTIF2. The IBD stands without the PA4744 seed. Reason: Core process; seed verdict SOUND and node term suits the clade. Supporting Evidence: PMID:15385567 Here we show that the Pseudomonas aeruginosa initiation factor IF-2 is required for formylation-independent protein initiation in P. aeruginosa
GO:0006413 translational initiation	IEA GO_REF:0000120	ACCEPT	Summary: Electronic mapping from the IF-2 family. Reason: Consistent with the experimental and IBA rows. Supporting Evidence: file:PSEAE/infB/infB-uniprot.txt One of the essential components for the initiation of protein synthesis.
GO:0006413 translational initiation	IMP PMID:15385567 The Pseudomonas aeruginosa initiation factor IF-2 is respons...	ACCEPT	Summary: PseudoCAP seed row. The abstract shows that PA IF-2 is required for formylation-independent initiation and that mutating its aminoacyl-binding cleft changes this behaviour, so the factor itself acts in initiation. Reason: Seed verdict SOUND; direct genetic and structure-function evidence for this gene. Supporting Evidence: PMID:15385567 increasing the positive charge potential of this cleft in the P. aeruginosa IF-2 prevented the protein from participating in formylation-independent protein initiation

Core Functions

Translational GTPase initiation factor IF-2. Binds initiator Met-tRNAfMet (formylated or, in P. aeruginosa, also unformylated), delivers it to the 30S subunit and hydrolyses GTP on 50S joining to form the 70S initiation complex.

Molecular Function:

translation initiation factor activity

Directly Involved In:

translational initiation

Cellular Locations:

cytosol

Supporting Evidence:

PMID:15385567
Here we show that the Pseudomonas aeruginosa initiation factor IF-2 is required for formylation-independent protein initiation in P. aeruginosa
file:PSEAE/infB/infB-uniprot.txt
Also involved in the hydrolysis of GTP during the formation of the 70S ribosomal complex.

GTP hydrolysis by the tr-type G domain drives the IF-2 cycle on the ribosome.

Molecular Function:

GTPase activity

Directly Involved In:

translational initiation

Supporting Evidence:

file:PSEAE/infB/infB-uniprot.txt
Also involved in the hydrolysis of GTP during the formation of the 70S ribosomal complex.

Gene Description

Existing Annotations Review

Core Functions

Translational GTPase initiation factor IF-2. Binds initiator Met-tRNAfMet (formylated or, in P. aeruginosa, also unformylated), delivers it to the 30S subunit and hydrolyses GTP on 50S joining to form the 70S initiation complex.

GTP hydrolysis by the tr-type G domain drives the IF-2 cycle on the ribosome.

References

Suggested Questions for Experts

Suggested Experiments

📚 Additional Documentation

Notes

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