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W G Haldenwang

Publications and source records attributed to W G Haldenwang.

7 recordsLinked to original sources
PubMed1992

Mutational analysis of the precursor-specific region of Bacillus subtilis sigma E.

sigma E is a sporulation-specific sigma factor of Bacillus subtilis that is formed from an inactive precursor protein (pro-sigma E) by the removal of 27 to 29 amino acids from the pro-sigma E amino terminus. By using oligonucleotide-directed mutagenesis, sequential deletions were constructed in the precursor-specific region of sigE and analyzed for their effect on the gene product's activity, ability to accumulate, and susceptibility to conversion into mature sigma E. The results demonstrated that the first 17 residues of the pro sequence contribute to silencing the sigma-like activity of pro-sigma E and that the amino acids between positions 12 and 17 are also important for its conversion into sigma E. Deletions that remove 21 or more codons from sigE reduce sigma E activity in cells which carry it, presumably by affecting pro-sigma E stability. A 26-codon deletion results in a gene whose product is not detectable in B. subtilis by either reporter gene activity or Western blot (immunoblot) assay. The primary structure as well as the size of the pro region of sigma E contributes to the protein's stability. The placement of additional amino acids into the pro region reduces the cell's ability to accumulate pro-sigma E. Additional sigE mutations revealed that the amino acids normally found at the putative processing site(s) of pro-sigma E are not essential to the processing reaction; however, a Glu residue upstream of these sites (position 25) was found to be important for processing. These last results suggest that the pro-sigma E processing apparatus does not recognize the actual site within pro-sigma E at which cleavage occurs but rater sequence elements that are upstream of this site.

Amino Acid Sequence↗
PubMed1992

Characterization of a regulatory network that controls sigma B expression in Bacillus subtilis.

The sigB operon of Bacillus subtilis encodes sigma B and three additional open reading frames (orfV, orfW, and orfX). Having previously mapped several mutations that alter the induction pattern of a sigma B-dependent promoter (ctc) to regions of cloned B. subtilis DNA which contain these three open reading frames, we directly tested the regulatory potential of orfV, orfW, and orfX by creating null alleles of each of these genes and examining the effects of the mutations, either singly or in pairs, on transcription of ctc and the sigB operon. Using lacZ reporter gene fusions and Northern (RNA) blot analyses, we have determined that all three genes modulate the activation of the sigma B-dependent promoters at both the sigB operon and ctc. Our data are consistent with the three gene products participating in a single pathway of negative control. orfW and orfX single-mutant strains have high levels of sigB and ctc transcription. sigB and ctc transcription in an orfV strain is similar to that found in mutant strains which lack sigma B itself. The orfV mutation is dominant to orfX but recessive to orfW. These results suggest that OrfW is the primary inhibitor of sigma B-dependent transcription and that OrfV is capable of counteracting the negative control of OrfW but is prevented from doing this by the orfX gene product.

Bacillus subtilis↗
PubMed1977

Physiological effects of growth of an Escherichia coli temperature-sensitive dnaZ mutant at nonpermissive temperatures.

The physiological effects of incubation at nonpermissive temperatures of Escherichia coli mutants that carry a temperature-sensitive dnaZ allele [dnaZ(Ts)2016] were examined. The temperature at which the dnaZ(Ts) protein becomes inactivated in vivo was investigated by measurements of deoxyribonucleic acid (DNA) synthesis at temperatures intermediate between permissive and nonpermissive. DNA synthesis inhibition was reversible by reducing the temperature of cultures from 42 to 30 degrees C; DNA synthesis resumed immediately after temperature reduction and occurred even in the presence of chloramphenicol. Inasmuch as DNA synthesis could be resumed in the absence of protein synthesis, we concluded that the protein product of the dnaZ allele (Ts)2016 is renaturable. Cell division, also inhibited by 42 degrees C incubation, resumed after temperature reduction, but the length of time required for resumption depended on the duration of the period at 42 degrees C. Replicative synthesis of cellular DNA, examined in vitro in toluene-permeabilized cells, was temperature sensitive. Excision repair of ultraviolet light-induced DNA lesions was partially inhibited in dnaZ(Ts) cells at 42 degrees C. The dnaZ(+) product participated in the synthesis of both Okazaki piece (8-12S) and high-molecular-weight DNA. During incubation of dnaZ(Ts)(lambda) lysogens at 42 degrees C, prophage induction occurred, and progeny phage were produced during subsequent incubation at 30 degrees C. The temperature sensitivity of both DNA synthesis and cell division in the dnaZ(Ts)2016 mutant was suppressed by high concentrations of sucrose, lactose, or NaCl. Incubation at 42 degrees C was neither mutagenic nor antimutagenic for the dnaZ(Ts) mutant.

Alleles↗
PubMed1977

Inhibition of bacteriophage M13 and phix174 duplex DNA replication and single-strand synthesis in temperature-sensitive dnaZ mutants of Escherichia coli.

A functional dnaZ product, known to be essential for host DNA polymerization and for the synthesis of M13 and phiX174 parental replicative-form (RF) DNA, is required also for RF replication and single-strand synthesis by both of these phages. All three stages of M13 and phiX174DNA replication (parental RF formation, RF replication, and single-strand synthesis) are inhibited in dnazts mutants at elevated temperatures. In addition, the thermolabile step in M13 parental RF formation appears to occur after RNA priming;i.e., the synthesis of M13 RF DNA proceeded when a dnaZts mutant, infected at a nonpermissive temperature, was transferred to a permissive temperature in the presence of rifampin.

Coliphages↗