The barley 60 kDa jasmonate-induced protein (JIP60) is a novel ribosome-inactivating protein.
The N-terminal region of a 60 kDa, jasmonate-induced protein of barley leaves (JIP60) is shown to be homologous to the catalytic domains of plant ribosome-inactivating proteins (RIP). Western blotting of leaf extracts and in vitro reconstitution experiments indicate that JIP60 is synthesized as a precursor which is processed in vivo. This is in keeping with in vitro translation experiments indicating that a deletion derivative of the N-terminal region, but not the putative precursor, strongly inhibits protein synthesis on reticulocyte ribosomes. The inhibition of ribosome function is associated with depurination of 26S rRNA, characteristic of plant RIPs. This indicates that JIP60 is a novel ribosome-inactivating protein requiring at least two processing events for full activation. JIP60 derivatives do not significantly inhibit in vitro protein synthesis on wheat germ ribosomes. These and other results suggest that JIP60 may be involved in plant defence.
Chaudhry
B
B
Carlsberg Research Laboratory, Carlsberg Laboratory, Valby, Denmark.
Müller-Uri
F
F
Cameron-Mills
V
V
Gough
S
S
Simpson
D
D
Skriver
K
K
Mundy
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016384:Consensus Sequence; D017931:DNA Primers; D001467:Hordeum / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010448:Peptide Initiation Factors / Q000737:chemistry; D018515:Plant Leaves; D010940:Plant Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D016133:Polymerase Chain Reaction; D012270:Ribosomes / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; C091875:JIP60 protein, Hordeum vulgare; D010448:Peptide Initiation Factors; D010940:Plant Proteins; C077382:eIF-4gamma