Biochemical properties of a novel cell wall protein associated with elongation growth in higher plants

A monoclonal antibody of IgM-type (TIM-11B2) was screened froma hybridoma library. The antibody recognizes a 40 kDa glycoprotein,p40, with high specificity. This protein was detected in allplant species examined so far and was found to be located bothsolubly and ionically-bound within the primary cell wall. The strongest immunobiochemical signals of p40 were found intissues undergoing elongation growth, whereas in other tissuesonly a faint signal could be detected. Those included the non-elongatingparts of different seedlings, such as the apical part of monocotprimary leaves or the leaves of dicots grown in light. Inhibitionof pea epicotyl growth by white light irradiation resulted ina strong decrease of the immunostain signal. On the other hand,induction of rapid coleoptile growth in rice seedlings inducedby submergence resulted in a strong increase of the immunobiochemicalsignal of p40. Time-course studies on the expression of p40during protoplast regeneration revealed that p40 is apparentlynot involved in cell wall formation. The hypothesis that p40is characteristic for tissues with the ability for elongationgrowth is discussed. Comparison of biochemical data and location of p40 with proteinsdescribed up to now indicate that this glycoprotein has notbeen characterized before. Key words: Cell wall protein, elongation growth, monoclonal antibody     

A novel beta-diketone-cleaving enzyme from Acinetobacter johnsonii: acetylacetone 2,3-oxygenase

A novel Fe+Zn containing oxygenase from Acinetobacter johnsonii catalyses 2,3-cleavage of acetylacetone to acetate and methylglyoxal has been purified. The stoichiometry of reactants and products conforms to a classical dioxygenase. The pure protein is a homotetramer of 64kD with variable amounts of Fe(2+) and Zn(2+). Activity of the enzyme is more closely related to the Fe(2+) content than to the amount of protein. A purification of acetylacetone 2,3-oxygenase, some of its physical properties, and the preference for some analogous substrates are described.     

Plant regeneration via somatic embryogenesis in pea (Pisum sativum L.)

Whole plant regeneration via somatic embryogenesis was obtained in pea (Pisum sativum L.) using explants from immature embryos or shoot apex segments. The induction of somatic embryos required picloram or 2,4-D. Germination of fully-developed embryos was accomplished by subculture on medium with only cytokinin and then on medium supplemented with cytokinins in combination with a reduced auxin concentration. Plantlets obtained from both zygotic embryos and shoot apices were transferred to soil and were grown to maturity. Nine plants were examined cytologically, revealing three tetraploids (2n=4x=28) and six diploids (2n=2x=14).Abbreviations Picloram 4-amino-3,5,6-trichloropicolinic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - NAA 1-naphthaleneacetic acid - BA 6-benzylaminopurine - IBA indole-3-butyric acid KAES Journal Article No. 87-3-4     

Assignment of the Auxin Binding Abilities of ABP44 in Gel

Several approaches were successfully performed to directly assignand characterize auxin binding of ABP₄₄ in gel. The 44 kDa highaffinity auxin binding protein ABP₄₄ from pea was tested forits ability to bind 5-azido-[7-³H]-IAA in photoaffinity labelingexperiments. Competition experiments with several auxin analoguesconfirm data published previously (Reinard and Jacobsen 1995).Critical reflections of the limitations of the method are alsodiscussed. Immunostaining using the antibody D16 (Napier andVenis 1992), which is directed against the putative bindingsite of ABP1, revealed that ABP₄₄'s auxin binding site is atleast partially related to the corresponding site of ABP1. Nevertheless,both proteins do not share any further immu-nological relationships.Our results with D16 recommend a careful reconsideration ofdata published by other authors. Furthermore, a 80 kDa, dimericglutathione dependent formaldehyde dehydrogenase (FDH) frommung bean, described recently, was found to be different fromABP₄₄. In contrast to the described FDH, ABP₄₄ exhibited noFDH activity. ³Recent address: Zentrum f. Molekularbiologie der Entziindung,Universitat Minister, v.-Esmarch-Str. 56, D-48149 Miinster,F.R.G.     

Analysis of RNase isozymes in germinating pea cotyledons by polyacrylamide-gel electrophoresis

In germinating pea cotyledons, at least three different RNase-isozymescan be detected by column chromatography (6). Polyacrylamidegel electrophoresis analysis in the present study revealed thepresence of five bands, with at least two being associated withheavily stained protein bands in reference gels. Assays carriedout in the presence of the nuclease inhibitor diethylpyrocarbonate(DEPC) showed that these bands were most likely artificial andnot ribonucleases (RNases). The nature of a fast-running componentwith the staining behavior of RNase, which neither can be inhibitedby DEPC nor is associated with a heavily stained protein band,is discussed. It may be a small molecule in the range of 20,000daltons. This band was also present in the cotyledons of dryseeds. When transfer RNA was used as a substrate in the assay,the band with the lowest mobility degraded this substrate veryrapidly. (Received January 23, 1980; )