Two Bacillus subtilis genes, designated resD and resE, encode proteins that are similar to those of twocomponent signal transduction systems and play a regulatory role in respiration. The overlapping resD-resE genes are transcribed during vegetative growth from a very weak promoter directly upstream of resD. They are also part of a larger operon that includes three upstream genes, resABC (formerly orfX14, -15, and -16), the expression of which is strongly induced postexponentially. ResD is required for the expression of the following genes: resA, ctaA (required for heme A synthesis), and the petCBD operon (encoding subunits of the cytochrome bf complex). The resABC genes are essential genes which encode products with similarity to cytochrome c biogenesis proteins. resD null mutations are more deleterious to the cell than those of resE. resD mutant phenotypes, directly related to respiratory function, include streptomycin resistance, lack of production of aa 3 or caa 3 terminal oxidases, acid accumulation when grown with glucose as a carbon source, and loss of ability to grow anaerobically on a medium containing nitrate. A resD mutation also affected sporulation, carbon source utilization, and Pho regulon regulation. The data presented here support an activation role for ResD, and to a lesser extent ResE, in global regulation of aerobic and anaerobic respiration in B. subtilis.

BaciUlus subtilis has an alkaline phosphatase (APase) gene

Alkaline phosphatase (APase) expression can be induced in Bacillus subtilis by phosphate starvation or by sporulation. We have recently shown that there are multiple APase structural genes contributing to the total alkaline phosphatase expression in B. subtilis. The expression of the alkaline phosphatase III gene (phoAIII) was analysed under both phosphate-starvation induction and sporulation induction conditions. phoAII is transcribed from two promoter regions, PV and PS. The PV promoter initiated transcription 37 bp before the translation initiation codon and was used to transcribe phoAIII during phosphate-starvation induction in vegetative cells. The PS promoter initiated transcription 119 bp before the translation initiation codon and was used during sporulation induction. Genes which have previously been shown to affect total vegatative APase, pho regulon genes phoP, phoR and phoS, affected expression of phoAIII during phosphate starvation. Genes known to affect expression of total sporulation APase, i.e. spoIIA, spoIIG and spoIIE, affected phoAIII expression during sporulation induction. Our data show that one member of the APase multigene family, phoAIII, contributes to the total APase expression both during phosphate-starvation induction and sporulation induction, and that the mechanism of regulation includes two promoters, each requiring different regulatory genes.

We have isolated full-length cDNA clones that encode oat (Avena sativa) seed storage globulin mRNAs from a cDNA library in the expression vector lambda gtll. The longest of these clones, pOG2, has an 1840-base pair insert that encodes a complete precursor subunit with a signal peptide of 24 amino acids followed by an acidic polypeptide of 293 amino acids and a basic polypeptide of 201 amino acids. Near the C terminus of the acidic polypeptide are four repeats of a higly conserved, glutamine-rich octapeptide. Other oat globulin cDNA clones contain five of these repeats. Nucleotide sequence comparisons between these clones indicate that the genes encoding these proteins are highly conserved. We estimate there to be 7 to 10 genes for the oat globulin per haploid genome. Comparisons of amino acid sequences show that the oat globulin is 30 to 40% homologous with storage globulins of legumes and about 70% homologous with the rice seed storage globulin (glutelin).During their development, plant seeds accumulate large amounts of storage proteins that serve as sources of nitrogen, sulfur, and carbon compounds during seed germination (25). Two major classes of storage proteins can be distinguished: globulins, which are found principally in the cotyledons and axis of the embryo, and prolamines, which are found in the endosperm of cereal seeds (13). Two major types of storage globulins have been described that have sedimentation coefficients ofabout 7S and 11S. The proportion of the two types of globulins is variable among dicots; monocot embryos contain only the 7S globulin, which is present in the scutellum.Storage globulins account for most of the protein in dicot seeds, but they generally make up only a small fraction of the protein found in cereal seeds. Instead, most cereals contain predominantly prolamine-type storage proteins. Oats and rice are exceptions. These two contain only small amounts ofprolamine (5-10%), and most of their storage protein is an 11 to 12S globulin that is synthesized in the endosperm. Both of these proteins are structurally related to the 11S globulins found in dicots (25), but both are much less soluble than the dicot 11S globulins. The oat globulin requires 0.8 to 1.0 M NaCl for solubility, whereas the characteristics of the rice globulin (glutelin) are such that denaturing solvents are required for solvation.Previous studies in our laboratory (29) and elsewhere (5, 7)

We have isolated and characterized cDNA clones encoding avenins, the prolamine storage proteins of oat seeds. Sequence analysis shows that avenins are a related group of polypeptides and that their mRNAs differ from each other by point mutations and small insertions and deletions. Avenin proteins have structural homology to the a/@-gliadins and r-gliadins of wheat, the B-hordeins of barley, and the r-secalins of rye. Hybridization analysis of DNA from various diploid, tetraploid, and hexaploid oat species shows that the oat genome contains more globulin storage protein genes than avenin genes and that some restriction fragments containing these genes are conserved between species with common genomes. We estimate that there are 25 avenin genes and 50 globulin genes per haploid genome in Avena sativa and similar ratios of globulin to avenin genes in other Avena species. Avenin and globulin polypeptides begin to accumulate between 4 days and 6 days after anthesis. Messenger RNAs encoding avenin and globulin proteins become abundant 4 days after anthesis and reach peak concentrations at 8 days after anthesis. Avenin mRNAs are present in somewhat greater molar amounts than globulin mRNAs beginning at 4 days after anthesis. Because there is considerably more globulin than avenin in the mature oat seed, the expression of globulin and avenin genes may be regulated both transcriptionally and post-transcriptionally.