Abstract
Ribosome-inactivating protein (RIP), a defence protein found in various plants, possesses different chain architectures and activation mechanisms. The RIP from barley (bRIP) is a type I RIP and has sequence features that are divergent from those of type I and type II RIPs from dicotyledonous plants and even the type III RIP from maize. This study presents the first crystal structure of an RIP from a cereal crop, barley, in free, AMP-bound and adenine-bound states. For phasing, a codon-optimized synthetic brip1 gene was used and a vector was constructed to overexpress soluble bRIP fusion proteins; such expression has been verified in a number of cases. The overall structure of bRIP shows folding similar to that observed in other RIPs but also shows significant differences in specific regions, particularly in a switch region that undergoes a structural transition between a 3(10)-helix and a loop depending on the liganded state. The switch region is in a position equivalent to that of a proteolytically susceptible and putative ribosome-binding site in type III RIPs. Thus, the bRIP structure confirms the detailed enzymatic mechanism of this N-glycosidase and reveals a novel activation mechanism for type I RIPs from cereal crops.
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Claims 5
Claim · model-written summary
Barley RIP has sequence features divergent from other plant RIP types.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaree0 - Gene
- bRIPe0
- Outcome
- sequence featurese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“RIP from barley (bRIP) is a type I RIP and has sequence features that are divergent from those of type I and type II RIPs from dicotyledonous plants and even the type III RIP from maize”
Claim · model-written summary
The barley RIP structure has a fold similar to other RIPs but differs in specific regions.
Not reportedTaxon
Verbatim
e0“overall structure of bRIP shows folding similar to that observed in other RIPs but also shows significant differences in specific regions”
Claim · model-written summary
A bRIP switch region shifts between a 3(10)-helix and loop according to liganded state.
Not reportedTaxon
Verbatim
e0“switch region that undergoes a structural transition between a 3(10)-helix and a loop depending on the liganded state”
Claim · model-written summary
The barley RIP switch region occupies the position of a putative ribosome-binding site in type III RIPs.
- Outcome
- position equivalent to that of a proteolytically susceptible and putative ribosome-binding sitee0
Not reportedTaxon
Verbatim
e0“switch region is in a position equivalent to that of a proteolytically susceptible and putative ribosome-binding site in type III RIPs”
Claim · model-written summary
The bRIP structure supports an enzymatic mechanism and reveals a new activation mechanism for cereal type I RIPs.
Not reportedTaxon
Verbatim
e0“bRIP structure confirms the detailed enzymatic mechanism of this N-glycosidase and reveals a novel activation mechanism for type I RIPs from cereal crops”