Studies have revealed in plant chloroplasts, mitochondria, cell wall and cytoplasm the existence of transglutaminase (TGase) activities, similar to those known in animals and prokaryotes, having mainly structural roles, but no protein has been associated to this type of activity in plants. A recent computational analysis has shown in Arabidopsis thaliana L. the presence of a gene, AtPng1p, which encodes a putative N-glycanase. AtPng1p contains the Cys-His-Asp triad present in the TGase catalytic domain. AtPng1p is a single gene expressed ubiquitously in the plant, but at low levels in all light assayed conditions. The recombinant AtPn1p protein could be immuno-detected using animal TGase antibodies. Furthermore, western blot analysis using antibodies raised against the recombinant AtPng1p protein have lead to its detection in microsomal fraction. The purified protein links polyamines - spermine (Spm) > spermidine (Spd) > putrescine (Put)- and biotin-cadaverine to dimethylcasein (DMC) in a calcium-dependent manner. Analyses of the -glutamyl-derivatives revealed that the formation of covalent linkages between proteins and polyamines occurs via the transamidation of -glutamyl residues of the substrate, confirming that the AtPng1p gene product acts as a TGase. The Ca2+- and GTP-dependent cross-linking activity of the AtPng1p protein can be visualized by the polymerization of bovine serum albumine (BSA), obtained, like the commercial TGase, at basic pH and in the presence of dithiotreitol (DTT). This is the first reported plant protein, characterized at molecular level, showing transglutaminase activity, as all its parameters analyzed so far agree with those typically exhibited by the animal TGases.
AtPng1p: first cloning and characterization of a plant transglutaminase.
DELLA MEA, MASSIMILIANO;SERAFINI FRACASSINI, DONATELLA;
2004
Abstract
Studies have revealed in plant chloroplasts, mitochondria, cell wall and cytoplasm the existence of transglutaminase (TGase) activities, similar to those known in animals and prokaryotes, having mainly structural roles, but no protein has been associated to this type of activity in plants. A recent computational analysis has shown in Arabidopsis thaliana L. the presence of a gene, AtPng1p, which encodes a putative N-glycanase. AtPng1p contains the Cys-His-Asp triad present in the TGase catalytic domain. AtPng1p is a single gene expressed ubiquitously in the plant, but at low levels in all light assayed conditions. The recombinant AtPn1p protein could be immuno-detected using animal TGase antibodies. Furthermore, western blot analysis using antibodies raised against the recombinant AtPng1p protein have lead to its detection in microsomal fraction. The purified protein links polyamines - spermine (Spm) > spermidine (Spd) > putrescine (Put)- and biotin-cadaverine to dimethylcasein (DMC) in a calcium-dependent manner. Analyses of the -glutamyl-derivatives revealed that the formation of covalent linkages between proteins and polyamines occurs via the transamidation of -glutamyl residues of the substrate, confirming that the AtPng1p gene product acts as a TGase. The Ca2+- and GTP-dependent cross-linking activity of the AtPng1p protein can be visualized by the polymerization of bovine serum albumine (BSA), obtained, like the commercial TGase, at basic pH and in the presence of dithiotreitol (DTT). This is the first reported plant protein, characterized at molecular level, showing transglutaminase activity, as all its parameters analyzed so far agree with those typically exhibited by the animal TGases.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
