Bacterial virus anti-defence systems · sequence & structure resource

Encyclopaedia of Bacterial Virus Anti-Defence Systems


Protein: Alt

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Overview

Mode of Action (MoA) performs ADP-ribosylation of MazF, abolishing its toxicity.
Evidence Infection assays showed that deletion of mazEF increased T4 phage burst size, implicating MazF as a defense factor. Mass spectrometry (ECO_0001096) revealed that MazF was mono-ADP-ribosylated with a 542 Da modification only during T4 infection, and this modification was absent when Alt was deleted (ECO_0001038), confirming Alt dependency. Site-directed mutagenesis identified Arg4 as the modified residue, and in vitro assays demonstrated that Alt catalyzes this modification using β-NAD⁺. Functional assays showed that ADP-ribosylation of MazF by Alt reduced its RNA cleavage activity by ~70%, supporting Alt’s role in neutralizing MazF toxicity during infection.
MoA Category adds a post-translational modification and deactivates bacterial defence
Subtype(s) of the defence system(s) inhibited by the protein Defence Subtype Escherichia coli type II TA system MazEF
Relevant publication(s) DOI 10.1111/mmi.13225
Other components of the anti-defence system Multicomponent System -
Known structure in PDB PDB ID -
Genome(s) encoding the protein Protein Source Enterobacteria phage T4
Defence system(s) inhibited by the protein Defences TA

3D structure

AlphaFold 3 model.

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Feature viewer - predicted secondary structure

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Pfam annotations

Pfam Name Pfam Acc Pfam Length Colour HMM Start HMM End Ali Start Ali End Env Start Env End Evalue
ADPrib_exo_Tox PF03496 196 1 195 374 614 374 615 6.3e-38

Sequence Viewer

Amino acid position: -

MELITELFDEDTTLPITNLYPKKKIPQIFSVHVDDAIEQPGFRLCTYTSGGDTNRDLKMGDKMMHIVPFTLTAKGSIAKLKGLGPSPINYINSVFTVAMQTMRQYKIDACMLRILKSKTAGQARQIQVIADRLIRSRSGGRYVLLKELWDYDKKYAYILIHRKNVSLEDIPGVPEISTELFTKVESKVGDVYINKDTGAQVTKNEAIAASIAQENDKRSDQAVIVKVKISRRAIAQSQSLESSRFETPMFQKFEASAAELNKPADAPLISDSNELTVISTSGFALENALSSVTAGMAFREASIIPEDKESIINAEIKNKALERLRKESITSIKTLETIASIVDDTLEKYKGAWFERNINKHSHLNQDAANELVQNSWNAIKTKIIRRELRGYALTAGWSLHPIVENKDSSKYTPAQKRGIREYVGSGYVDINNALLGLYNPDERTSILTASDIEKAIDNLDSAFKNGERLPKGITLYRSQRMLPSIYEAMVKNRVFYFRNFVSTSLYPNIFGTWMTDSSIGVLPDEKRLSVSIDKTDEGLVNSSDNLVGIGWVITGADKVNVVLPGGSLAPSNEMEVILPRGLMVKVNKITDASYNDGTVKTNNKLIQAEVMTTEELTESVIYDGDHLMETGELVTMTGDIEDRVDFASFVSSNVKQKVESSLGIIASCIDIANMPYKFVQG