No abstract

In maize (Zea mays L.) three isoforms of starch-branching enzyme (SBEI, SBElla, and SBEllb) are involved in the synthesis of amylopectin, the branched component of starch. To isolate a cDNA encoding SBElla, degenerate oligonucleotides based on domains highly conserved in Sbe2 family members were used to amplify SbeZ-family cDNA from tissues lacking SBEllb activity. l h e predicted amino acid sequence of a SbeZa cDNA matches the N-terminal sequence of SBElla protein purified from maize endosperm. l h e size of the mature protein deduced from the cDNA also matches that of SBElla. Features of the predicted protein are most similar to members of the SBEll family; however, it differs from maize SBEllb in having a 49-amino acid N-terminal extension and a region of substantial sequence divergence. SbePa mRNA levels are 1 O-fold higher in embryonic than in endosperm tissue, and are much lower than SbeZb in both tissues. Unlike SbeZb, SbeZa-hybridizing mRNA accumulates in leaf and other vegetative tissues, consistent with the known distribution of SBElla and SBEllb activities.SBE catalyzes the formation of a(1-6) branches in amylopectin, the highly branched component of starch. It cleaves a ( l 4 ) bonds on linear glucosyl chains and reattaches the released glucan segments to the same or another glucosyl chain by a(1-6) linkages. The reaction creates not only branches, but also new, nonreducing ends for further a(14) glucan elongation. Multiple forms of SBE have been characterized in many species, including rice (Mizuno et al

Antimicrobial activity of seven bacteriocins produced by lactic acid bacteria against Helicobacter pylori strains (ATCC 43504, Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH [DSM] 4867, DSM 9691, and DSM 10242) was investigated in vitro using a broth microdilution assay. The bacteriocins chosen for the study were nisin A; lacticins A164, BH5, JW3, and NK24; pediocin PO2; and leucocin K. Antimicrobial activity of the bacteriocins varied among the H. pylori strains tested, of which strain ATCC 43504 was the most tolerant. Among the bacteriocins tested, lacticins A164 and BH5 produced by Lactococcus lactis subsp. lactis A164 and L. lactis BH5, respectively, showed the strongest antibacterial activity against H. pylori strains. MICs of the lacticins against H. pylori strains, when assessed by the critical dilution micromethod, ranged from 0.097 to 0.390 mg/liter (DSM strains) or from 12.5 to 25 mg/liter (ATCC 43504), supporting the strain-dependent sensitivity of the pathogen. Pediocin PO2 was less active than the lacticins against four strains of H. pylori, and leucocin K was the least active peptide, with no inhibition toward H. pylori ATCC 43504. Anti-Helicobacter activity of lacticin A164 was dependent on initial inoculum size as well as concentration of the bacteriocin added.

Environmental stimuli, including light, pathogens, hormones, and abiotic stresses, elicit changes in the cytosolic Ca2+ signatures of plant cells. However, little is known about the molecular mechanisms by which plants sense and transmit the specific cytoplasmic Ca2+ signal into the nucleus, where gene regulation occurs to respond appropriately to the stress. In this study, we have identified two novel Arabidopsis (Arabidopsis thaliana) proteins specifically associated with Calcineurin B-Like-Interacting Protein Kinase1 (CIPK1), a member of Ser/Thr protein kinases that interact with the calcineurin B-like Ca2+-binding proteins. These two proteins contain a very similar C-terminal region (180 amino acids in length, 81% similarity), which is required and sufficient for both interaction with CIPK1 and translocation to the nucleus. Interestingly, the conserved C-terminal region was also found in many proteins from various eukaryotic organisms, including humans. However, none of them have been characterized so far. Taken together, these findings suggest that the two proteins containing the evolutionarily conserved C-terminal region (ECT1 and ECT2) may play a critical role in relaying the cytosolic Ca2+ signals to the nucleus, thereby regulating gene expression.