The complete amino Acid sequence for the anaerobically induced aldolase from maize derived from cDNA clones

A cDNA library was synthesized from maize anaerobic root mRNA and screened with cDNA specific to the anaerobically induced Zea mays cytoplasmic aldolase. At least 1% of the cDNA of the library corresponded to maize cytoplasmic aldolase. The sequence of four overlapping cDNA clones encoded a protein of molecular weight 38,611 homologous to aldolase. These cDNAs were polymorphic at three bases and one of these cDNAs had a different, shorter 3′-untranslated region. No known eukaryotic poly(A) addition site was detected. The derived amino acid sequences of maize was compared to the sequence of aldolase of trypanosome, Drosophila, and two mammalian isozymes, A and B. Of these, maize cytoplasmic aldolase was found to have the highest homology (55%) with rabbit aldolase A.     

Interactions of Bacillus subtilis RNA polymerase with subunits determining the specificity of initiation. Sigma and delta peptides can bind simultaneously to core

The Bacillus subtilis RNA polymerase sigma 43 subunit and the phage SP82 encoded 28-kDa peptide are responsible for the binding of RNA polymerase to early and middle SP82 promoters, respectively. The delta peptide enhances the specificity of the interaction of B. subtilis RNA polymerase with these promoters. We have used sedimentation experiments to determine the effect of each of the three specificity factors, delta, sigma, and the 28-kDa peptide, on the binding of the other two factors to RNA polymerase core and the effect of NaCl on these binding equilibria. We show that sigma 43 and the 28-kDa peptide can each bind to RNA polymerase core at the same time as delta. Sigma 43 and the 28-kDa peptide have similar affinities to core at 0.1 M NaCl, but the 28-kDa peptide binds to core-delta more strongly than sigma 43. The implications of these findings with respect to the replacement of sigma 43 by the 28-kDa peptide and the mechanism of promoter search by B. subtilis RNA polymerase are discussed.     

Evidence that sigma factors are components of chloroplast RNA polymerase.

Plastid genes are transcribed by DNA-dependent RNA polymerase(s), which have been incompletely characterized and have been examined in a limited number of species. Plastid genomes contain rpoA, rpoB, rpoC1, and rpoC2 coding for alpha, beta, beta', and beta" RNA polymerase subunits that are homologous to the alpha, beta, and beta' subunits that constitute the core moiety of RNA polymerase in bacteria. However, genes with homology to sigma subunits in bacteria have not been found in plastid genomes. An antibody directed against the principal sigma subunit of RNA polymerase from the cyanobacterium Anabaena sp. PCC 7120 was used to probe western blots of purified chloroplast RNA polymerase from maize, rice, Chlamydomonas reinhardtii, and Cyanidium caldarium. Chloroplast RNA polymerase from maize and rice contained an immunoreactive 64-kD protein. Chloroplast RNA polymerase from C. reinhardtii contained immunoreactive 100- and 82-kD proteins, and chloroplast RNA polymerase from C. caldarium contained an immunoreactive 32-kD protein. The elution profile of enzyme activity of both algal chloroplast RNA polymerases coeluted from DEAE with the respective immunoreactive proteins, indicating that they are components of the enzyme. These results provide immunological evidence for sigma-like factors in chloroplast RNA polymerase in higher plants and algae.     

Evidence that the Extracytoplasmic Function Sigma Factor ςE Is Required for Normal Cell Wall Structure in Streptomyces coelicolor A3(2)

The sigE gene of Streptomyces coelicolor A3(2) encodes an RNA polymerase sigma factor belonging to the extracytoplasmic function (ECF) subfamily. Constructed sigE deletion and disruption mutants were more sensitive than the parent to muramidases such as hen egg white lysozyme and to the CwlA amidase from Bacillus subtilis. This correlated with an altered muropeptide profile, as determined by reverse-phase high-performance liquid chromatography analysis of lytic digests of purified peptidoglycan. The sigE mutants required high levels of magnesium for normal growth and sporulation, overproducing the antibiotic actinorhodin and forming crenellated colonies in its absence. Together, these data suggest that sigE is required for normal cell wall structure. The role of ς^E was further investigated by analyzing the expression of hrdD, which is partially sigE dependent. The hrdD gene, which encodes the ς^HrdD subunit of RNA polymerase, is transcribed from two promoters, hrdDp₁ and hrdDp₂, both similar to promoters recognized by other ECF sigma factors. The activities of hrdDp₁ and hrdDp₂ were reduced 20- and 3-fold, respectively, in sigE mutants, although only hrdDp₁ was recognized by Eς^E in vitro. Growth on media deficient in magnesium caused the induction of both hrdD promoters in a sigE-dependent manner.     

Analysis of the evolution of the family of the Sig genes encoding plant sigma factors

Within the latter decade, sigma subunits of bacterial-type RNA polymerases were found in eukaryote cells. In the higher plants and algae, these subunits determine the promoter specificity of the chloroplast multisubunit RNA polymerase. In the higher plants, sigma subunits are encoded by the family of nuclear Sig genes comprising 5–6 genes. Several conclusions as to the evolution of this gene family were deduced from the comparison of the deduced amino acid sequences and the sites of intron location.