Properties of calcium-dependent regulatory proteins from fungi and yeast

Calmodulins were isolated from vegetative mycelia of Basidiomycetes fungi, Agaricus campestris and Coprinus lagopus. These calmodulins showed similar mobilities to those of animal calmodulins on nondenaturing polyacrylamide gel electrophoresis in the presence or absence of Ca2+. The molecular weights of both calmodulins were determined to be 16,000. Agaricus calmodulin consisted of 148 amino acids including epsilon-N-trimethyllysine and cysteine. The UV-absorption spectrum showed the relatively high content of phenylalanine in Basidiomycetes calmodulins. The difference UV-absorption spectrum due to the blue shift by Ca2+ was observed. Both calmodulins activated muscle myosin light chain kinase and pea NAD+ kinase in a Ca2+-dependent manner, and the activities were inhibited by trifluoperazine or chlorpromazine. A calmodulin-like protein was partially purified from baker's yeast, Saccharomyces cerevisiae. However, detection of a calmodulin-like protein in prokaryotes was not successful.     

Stimulation of RecA-mediated cleavage of phage phi 80 cI repressor by deoxydinucleotides

The presence of either deoxyguanylyl-(3'----5')-deoxyguanosine (d(G-G] or deoxyadenylyl-(3'----5')-deoxyguanosine (d(A-G] greatly stimulates cleavage of the phage phi 80 cI repressor mediated by the Escherichia coli RecA protein in vitro. No other deoxydinucleoside monophosphate or riboguanylyl-(3'----5')-guanosine (r(G-G] affects the cleavage reaction. Neither the cleavage site of the phi 80 cI repressor nor the requirement for single-stranded DNA and ATP for cleavage is altered by d(G-G). Photoaffinity labeling experiments with 32P-labeled 5'-phosphoryl deoxyguanylyl deoxyguanosine (pd(G-G], which also stimulates cleavage, show that pd(G-G) bound to the repressor under the conditions in which the repressor is cleaved by RecA protein. The binding increases the affinity of the repressor for RecA protein and thus greatly stimulates repressor cleavage. The cleavage reactions of LexA and lambda cI repressors by RecA protein are not affected by d(G-G).     

Hydrolysis of solubilized fibroin and silk proteins in the midgut of the pharate adult of Bombyx mori

Midgut protease in the pharate adult hydrolysed native silk proteins and solubilized fibroin by ethylenediamine cupric hydroxide or lithium bromide. By agar gel electrophoresis one to three protease bands moving toward the anode were detected, and the number of bands and the electrophoretic mobility were different among the various strains. Optimal activity of the enzyme was at about pH 8·3. The protease activity was found to decrease in higher concentrations of the substrates. One peak of protease activity was seen in Sepharose 6B chromatography, and the elution pattern and peak position of the enzyme were very similar to those of protease activity with casein. In DEAE-cellulose chromatography, the peak of activity for casein overlapped but did not coincide with a broad peak of protease hydrolysing native silk proteins. The results obtained support the assumption that the midgut protease in the pharate adult is one of the sources of the cocoon-digesting enzyme.     

An algorithm for the bonding-probability map of nucleic acid secondary structure

We report a more efficient and well-defined algorithm for predicting a secondary structure of single-stranded nucleic acid from a primary nucleotide sequence. Using this algorithm, one- and two-dimensional bonding-probability maps of 5S rRNA of thermus thermophilus HB8 were calculated. These maps well express the stability of the secondary structure.     

Exchange reactions catalyzed by methioninase from Pseudomonas putida.

Highly purified methioninase from Pseudomonas putida, which catalyzes alpha, gamma-elimination reactions of homocysteine and its S-substituted derivatives as well as alpha, beta-elimination reactions of cysteine and its derivatives, was found to catalyze exchange reactions between the substituent at the gamma-carbon of homocysteine substrates and exogenously added alkanethiols, forming the corresponding S-alkylhomocysteines. It also catalyzed similar beta-exchange reactions between cysteine and alkanethiols. Thus, all the substrates for the methioninase-catalyzed elimination reactions also appear to be available for the exchange reactions.     

The A5 antigen, a candidate for the neuronal recognition molecule, has homologies to complement components and coagulation factors

The A5 antigen is a neuronal cell surface protein of Xenopus presumed to be involved in the neuronal recognition between the optic nerve fibers and the visual centers. Analyses of cDNA clones revealed that the A5 antigen is a class I membrane protein containing two different internal repeats in the extracellular segment. The first repeat bears homology to domain III of complement components C1r and C1s, and the second repeat is homologous to the C1 and C2 domains of coagulation factors V and VIII. The mRNA for the A5 antigen was present in retinal ganglion cells and visual center neurons. Nonneuronal cells in the peripheral and central nervous systems did not express the mRNA for the A5 antigen.