Characterization and Expression of a Novel Member (JBURE-II) of the Urease Gene Family from Jackbean [Canavalia ensiformis (L.) DC]

Abstract

;Canavalia ensiformis (jackbean) seeds contain the proteins urease and canatoxin, a variant form of the jackbean urease. Here we have cloned a cDNA encoding another isoform of urease, called JBURE-II. This cDNA was obtained by RT-PCR using as template total RNA extracted from C. ensiformis tissues. Nucleotide sequence analysis showed that JBURE-II clones share 86% similarity with known jackbean urease. The presence in C. ensiformis of a family of urease-related genes with at least three members was demonstrated by Southern blot analysis. In order to understand the pattern of expression of the JBURE-II gene, we collected tissue samples from different stages of flower and embryo development. The results of RT-PCR show that JBURE-II is expressed from flower buds throughout seed maturation. Semi-quantitative RT-PCR indicates that expression of urease and JBURE-II genes is induced in seedlings and in leaves treated with abscisic acid, a phytohormone involved in seed maturation and wound response. This work constitutes the first report on the presence of a family of urease genes in jackbean, and provides characterization of a cDNA encoding a new member of this gene family.

Central and peripheral neurotoxicity induced by the Jack Bean Urease (JBU) in Nauphoeta cinerea cockroaches

“…Ureases are widespread in plants, fungi, and bacteria but are not synthesized by animals (Mobley and Hausinger, 1989). Canavalia ensiformis displays several urease isoforms: the most abundant one Jack Bean Urease (JBU) (Sumner, 1926), canatoxin (CNTX) (Carlini and Guimarães, 1981;Follmer et al, 2001) and JBURE-II (Mulinari et al, 2011;Pires-Alves et al, 2003). The entomotoxic action of C. ensiformis ureases has been shown in different insect models (Stanisçuaski and Carlini, 2012).…”

Ureases display biological effects independent of enzymatic activity: Is there a connection to diseases caused by urease-producing bacteria?

“…Canatoxin, which consists of a noncovalently linked dimer of 95-kDa acidic polypeptide chains, was characterized recently as a variant form of the classical more abundant jack bean urease (8). RT-PCR applied to mRNA isolated from C. ensiformis tissues and Southern blots confirmed the presence of a family of urease-related genes with at least two members sharing 86% similarity (9). Jack bean ureases presented differential behavior in immobilized metal affinity chro- matography enabling separation of the isoenzymes (8,10).…”

Global and targeted proteomics in developing jack bean (Canavalia ensiformis) seedlings: an investigation of urease isoforms mobilization in early stages of development

“…A third gene encoding a urease isoform designated jbure-II was described by Pires-Alves et al 2003, accession number AF468788. A correction of this sequence, designated jbure-IIb, was submitted to Gene Bank and received the accession number EU938655 (Mulinari et al, unpublished).…”

“…Ureases (EC.3.5.1.5, urea amidohydrolases) are nickel-dependent metalloenzymes present in plants, fungi and bacteria (Mobley and Hausinger 1989) that catalyze the conversion of urea into two molecules of ammonia and one carbon dioxide (Dixon et al1975;Carlini and Polacco 2008). In jack bean there are at least three urease isoforms: the major (more abundant) jack bean urease (JBU); the neurotoxic protein canatoxin (CNTX) (Carlini and Guimarães 1981;Follmer et al 2001) and JBURE-II (Pires-Alves et al 2003). CNTX displays about 30% of JBU ureolytic activity (Follmer et al 2001).…”