A cathepsin F-like peptidase involved in barley grain protein mobilization, HvPap-1, is modulated by its own propeptide and by cystatins.
Among the C1A cysteine proteases, the plant cathepsin F-like group has been poorly studied. This paper describes the molecular and functional characterization of the HvPap-1 cathepsin F-like protein from barley. This peptidase is N-glycosylated and has to be processed to become active by its own propeptide being an important modulator of the peptidase activity. The expression pattern of its mRNA and protein suggest that it is involved in different proteolytic processes in the barley plant. HvPap-1 peptidase has been purified in Escherichia coli and the recombinant protein is able to degrade different substrates, including barley grain proteins (hordeins, albumins, and globulins) stored in the barley endosperm. It has been localized in protein bodies and vesicles of the embryo and it is induced in aleurones by gibberellin treatment. These three features support the implication of HvPap-1 in storage protein mobilization during grain germination. In addition, a complex regulation exerted by the barley cystatins, which are cysteine protease inhibitors, and by its own propeptide, is also described.
Centro de Biotecnología y Genómica de Plantas (UPM-INIA), Campus Montegancedo, Universidad Politécnica de Madrid, Autovía M40 (Km 38),   28223-Pozuelo  de Alarcón,  Madrid,  Spain.
Ines
I
Cambra
Manuel
M
Martinez
Beatriz
B
Dáder
Pablo
P
González-Melendi
Jacinto
J
Gandullo
M Estrella
ME
Santamaría
Isabel
I
Diaz
D000418:Albumins / Q000378:metabolism; D000595:Amino Acid Sequence; D001692:Biological Transport; D056646:Cathepsin F / Q000235:genetics / Q000378:metabolism*; D015891:Cystatins / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D056625:Endosperm / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D018525:Germination; D005916:Globulins / Q000378:metabolism; D005983:Glutens / Q000378:metabolism; D006031:Glycosylation; D001467:Hordeum / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D019684:Magnoliopsida / Q000201:enzymology / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D059748:Proteolysis; D011994:Recombinant Proteins; D013997:Time Factors
D000418:Albumins; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D004792:Enzyme Precursors; D005916:Globulins; D010940:Plant Proteins; D011994:Recombinant Proteins; D005983:Glutens; D056646:Cathepsin F