Nodulin�22 from Phaseolus vulgaris protects Escherichia coli cells from oxidative stress

Abstract

Plant genes that are induced during the formation and function of a root nodule are called nodulin genes. Cloning and functional analysis of nodule-specific gene products are of valuable help in establishing the role and requirements of the host plant for the specificity and effectiveness of the symbiosis. A cDNA clone (nod22) was isolated from Phaseolus vulgaris L. (common bean) cDNA library derived from Rhizobium-infected roots. Nodulin 22 (Nod22) transcripts are accumulated from early to late stages in root nodule development. RT-PCR in situ studies indicated that Nod22 transcripts are highly accumulated in cortical, vascular bundle and infected cells. The deduced Nod22 protein contains a highly hydrophobic N-terminus, with signal peptide characteristics, and a C-terminal extension with high identity to the alpha-crystallin domains found in alpha-crystallin lens chaperone, and other small heat-shock proteins. These domains have not been previously described in other known nodulins, but have been observed in small heat-shock proteins found in plant tissues exposed to elevated temperature and oxidative stress. Nod22, when it is over-expressed in Escherichia coli, cells confers protection against oxidative stress suggesting its possible role in plant host protection from oxidative toxicity during the Rhizobium-legume symbiosis.

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“…High expression of nodulin-like proteins in dying xylem fibers suggests that nodulins, which regulate nodule formation in response to Rhizobium infection, also have an important function in the maturation of xylem fibers. Interestingly, certain nodulins have been shown to regulate accumulation of reactive oxygen species (ROS) [24,25], and it is possible that nodulin-like proteins regulate ROS accumulation that occurs during the late maturation or cell death of xylem fibers. ROS accumulation is also implied by the high expression levels of peroxidases (POPLAR.11659 and 11669) and a protein kinase (singleton X053F08) that seems to encode the Populus ortholog of Arabidopsis thaliana OPEN STOMATA 1 ( OST1 ; Figure 5).…”

Proteomic and functional analyses of Nelumbo nucifera annexins involved in seed thermotolerance and germination vigor

“…Cell viability after treatments with high temperatures were assessed by the protocol as previously described (Mohammad et al 2004;Soto et al 1999). E. coli strain BL21 (DE3) cell cultures transformed with pET14b or pET14b-NnANN1 were grown at 37°C to an OD 600 of 1.0 without IPTG induction and then diluted with fresh Luria-Bertani medium to an OD 600 of 0.4.…”

Genotype-specific regulation of cold-responsive genes in cypress (Cupressus sempervirens L.)

“…It is therefore not surprising that some of the genes induced in plants during nodule formation (generally called nodulins) showed a protective function against oxidative stress. In Phaseolus vulgaris a nodulin sequence (nod22) showing high amino acid identity with some members of the ubiquitous small heat-shock proteins (sHsps) was found to confer protection against oxidative stress when overexpressed in E. coli cells (Mohammad et al, 2004). Cyplp003 was overexpressed only in two cypress genotypes (accession 8 and accession 16) used in this study (Fig.…”