The study of pectin methylesterase and wall-loosening enzyme activities in situ, as well as the estimation of the electrostatic potential of the cell wall, suggest a coherent picture of the role played by metal ions and pH in cell-wall extension. Cell-wall growth brings about a decrease of local proton concentration because the electrostatic potential difference (delta psi) of the wall decrease...

When grown on xanthan as a carbon source, the bacterium Bacillus sp. strain GL1 produces extracellular xanthan lyase (75 kDa), catalyzing the first step of xanthan depolymerization (H. Nankai, W. Hashimoto, H. Miki, S. Kawai, and K. Murata, Appl. Environ. Microbiol. 65:2520-2526, 1999). A gene for the lyase was cloned, and its nucleotide sequence was determined. The gene contained an open readi...

O-Acetylserine (thiol) lyase, the last enzyme in the cysteine biosynthetic pathway, was purified to homogeneity from spinach leaf chloroplasts. The enzyme has a molecular mass of 68,000 and consists of two identical subunits of Mr 35,000. The absorption spectrum obtained at pH 7.5 exhibited a peak at 407 nm due to pyridoxal phosphate, and addition of O-acetylserine induced a considerable modifi...

The N-acetylneuraminate (NANA) lyase (EC 4.1.3.3) gene from Escherichia coli was self-cloned in E. coli. Transformants were selected by complementation of a NANA lyase-deficient E. coli strain. One clone was found to produce NANA lyase, and it contained a recombinant plasmid, pNAL1, with a 9.0-kilobase HindIII insert. The cloning of the NANA lyase gene resulted in the change from inducible to c...

Density-labeling with 10 millimolar K(15)NO(3)/70% (2)H(2)O has been used to investigate isocitrate lyase synthesis during greening of sunflower (Helianthus annuus L.) cotyledons when the glyoxysomal enzyme activities sharply decline and the transition in cotyledonary microbody function occurs. A density shift of 0.0054 (kilograms per liter) was obtained for the profile of isocitrate lyase acti...

A rhamnogalacturonan hydrolase gene of Aspergillus aculeatus was used as a probe for the cloning of two rhamnogalacturonan hydrolase genes of Aspergillus niger. The corresponding proteins, rhamnogalacturonan hydrolases A and B, are 78 and 72% identical, respectively, with the A. aculeatus enzyme. In A. niger cultures which were shifted from growth on sucrose to growth on apple pectin as a carbo...

Xanthomonas oryzae pv.oryzae (Xoo) causes the serious bacterial blight disease of rice. Xoo secretes a repertoire of plant cell wall degrading enzymes (CWDEs) like cellulases, xylanases, esterases etc., which act on various components of the rice cell wall. The major cellulases and xylanases secreted by Xoo have been identified and their role in virulence has been determined. In this study, we ...