Isolamento e localização imunohistoquímica de apirase de galha globosa de Calliandra brevipes BENTH (Fabaceae: Mimosoidae) usando anticorpos contra NTPDases e seu domínio B conservado

Abstract

By alignment of amino acid sequences of the S. tuberosum apyrase and isoforms from other plant species, high identity (46 to 94%) and similarity (64 to 96%) were identified between them, including distinct species of Fabaceae, and closer structural relationship was found between the domains B from these proteins. Polyclonal antibodies anti- S. tuberosum potato apyrase inhibited 65-80% of the catalytic activity of this protein. In addition, polyclonal immune sera produced against homologue synthetic peptides potB1LJ, LbB1LJ and SmB1LJ or potB2LJ, LbB2LJ and SmB2LJ, derivatives from B domains of NTPDases isoforms, significantly inhibited (32 to 44%) potato apyrase activity. These antibodies could be useful molecular tools for studies of the apyrase isoforms. The apyrase activity from the non-galled stem (NS), non-galled leaf (NL), or globose gall (GG) tissue from Calliandra brevipes BENTH (Fabaceae: Mimosoidae) was tested in reaction medium pH 7.4 and in the presence of C12E9, the ADP, UDP or GDP hydrolysis by GG was 1.8 to 2.4 fold higher than non-galled tissues. Polyclonal antibodies anti-potato apyrase significantly inhibited (70 to 90%) the ATP, ADP, GDP or UDP hydrolysis by NS. In GG, similarly, the ATPase, GDPase, ADPase or UDPase activity was also significantly inhibited (40-66%). For isolation and identification of apyrase from normal tissues and globose gall from the Calliandra brevipes, sample of NS, NL or GG tissue was previously homogenised in Triton X-100 plus sodium deoxycholate, and fractionated in non-denaturing gel containing the same detergents. Using ADP as the substrate, the enzyme catalytic activity gave rise to the appearance of a single calcium phosphate precipitate band displaying identical electrophoretic mobilities in NS, NL, and GG samples, being more intense in this last one suggesting that apyrase is over-expressed in this tissue. In this band of higher mobility, a number of distinct polypeptides ranging from 52 to 75 kDa were recognized by cross-immunoreactivity with polyclonal anti-potato apyrase antibodies, suggesting the existence of active forms of the same protein with different net charges, possibly as a result of distinct glycosylation levels. In addition, an immunoreactive band of approximately 52 kDa, of lower mobility and activity, was also identified in all tissues, possibly apyrase in completely deglycosylated form. By histochemical techniques and light microscopy, micrometric sections stained with lugol or Astra Blue-Saphranine evidenced the chamber pulpal widely surrounded by nutritive tissue containing starch in its distal portion, and cortical parenchime delimited by rings sclereides lignified. By histochemical techniques, the ADPase or ATPase activity was found as a granular dense lead phosphate deposit distributed at the external surface, and inside of the nutritive cells of the globose gall. By immunohistochemical techniques, using confocal laser scanning microscopy and antibodies anti-potato apyrase and anti-synthetic peptides, the gall globose apyrase was found at same sites. In addition, the time of laboratory germination of C. brevipes seed was determined, and on the fifth day after test installation, the first leaf opened, identifying rapid growing tissues suitable for further investigations on the participation of both apyrase and regulation of ATP hydrolysis in cell proliferation.