The Acinetobacter calcoaceticus NCIB8250 mop operon mRNA is differentially degraded, resulting in a higher level of the 3' CatA-encoding segment than of the 5' phenolhydroxylase-encoding portion.

The 7.5-kb polycistronic mop mRNA is differentially degraded in Acinetobacter calcoaceticus. The 4.9-kb 5' portion of the transcript contains the genes mopKLMNOP, encoding the multi-component phenol hydroxylase, and its 5' end decays three times faster than the 2.3-kb 3' portion encoding catechol 1,2-dioxygenase (catA). Larger amounts of the catA mRNA than the mopKLMNOP mRNA are present in the cells as a result of this processing. The site for endonucleolytic cleavage is located in the intercistronic region between mopP and catA, and contains a potential stem-loop structure and a putative RNase E cleavage site. Decay of the mop mRNA in Escherichia coli depends on RNase E. Thus, we propose that an RNase E-like activity is also present in A. calcoaceticus. Expression of MopN, one polypeptide of the multi-component phenol hydroxylase, interferes with growth of A. calcoaceticus. Thus, harmful expression of MopN may be reduced by rapid decay of its mRNA, indicating that mRNA processing contributes to differential gene expression in the large mop operon of A. calcoaceticus NCIB8250.

Expression, inducer spectrum, domain structure, and function of MopR, the regulator of phenol degradation in Acinetobacter calcoaceticus NCIB8250.

Degradation of phenol by Acinetobacter calcoaceticus NCIB8250 involves (sigma54-dependent expression of a multicomponent phenol hydroxylase and catechol 1,2-dioxygenase encoded by the mop operon. Complementation of a new mutant deficient in phenol utilization yielded the regulatory locus mopR. It is located in divergent orientation next to the mop operon. MopR is constitutively expressed at a low level from a sigma70-type promoter and belongs to the NtrC family of regulators. The amino acid sequence is similar to that of XylR regulating xylene degradation and to that of DmpR regulating dimethylphenol degradation in Pseudomonas spp. However, it shows a different effector profile for substituted phenols than DmpR. MopR activates phenol hydroxylase expression in the presence of phenol in Escherichia coli, indicating that it binds the effector. The phenol binding A domains of MopR and DmpR have fewer identical residues than the A domains of DmpR and XylR, despite the fact that XylR recognizes different effectors. This suggests that sequence conservation in the A domain does not reflect the potential to bind the respective effectors. Overexpression of the MopR A domain in the presence of wild-type MopR causes loss of mop inducibility by phenol, establishing its negative transdominance over MopR. Deletion of 110 residues from the N terminus did not affect transdominance of the truncated domain, whereas deletion of 150 residues abolished it completely. This result establishes the distinction of two subdomains, A(N) and A(C), which together constitute the A domain. The C-terminal portion of the A domain, A(C), shows considerable affinity for the C domain, even in the presence of the trigger phenol.

Genetic organization, nucleotide sequence and regulation of expression of genes encoding phenol hydroxylase and catechol 1,2-dioxygenase in Acinetobacter calcoaceticus NCIB8250.

We have mutated Acinetobacter calcoaceticus NCIB-8250 to growth deficiency on phenol as sole carbon source and isolated genes with similarity to phenol hydroxylase and catechol 1,2-dioxygenase by complementation. Sequence analysis reveals the presence of six open reading frames (ORFs) with similarities to a Pseudomonas multicomponent phenol hydroxylase which are followed by an ORF with similarity to catA from A. calcoaceticus ADP1. Transformation of these genes to ADP1 confers the ability to grow at the expense of phenol as sole carbon source. Primer extension analysis indicates phenol-inducible transcription from an RpoN-dependent promoter sharing sequence similarity with the sigma 54 consensus promoter sequence, except that the -12 box is GG instead of GC. A catA::lacZ transcriptional fusion shows the same induction profile for beta-galactosidase expression as transcription from the sigma 54-dependent promoter. This result suggests that catA is cotranscribed in the same operon with the phenol hydroxylase-encoding genes and is consistent with the fact that no apparent additional promoter is found for catA by sequence analysis or primer extension. Catechol 1,2-dioxygenase activity is induced in NCIB8250 by benzoate, whereas beta-galactosidase expression from the catA::lacZ fusion is not. This observation leads to the hypothesis that two differentially regulated catA genes should be present in that strain.

[Type A behavior--a uniform construct?]. / Das Typ-A-Verhalten--ein einheitliches Konstrukt?

Single dimensions of the Type-A-behaviour pattern and their contributions to the etiology and pathogenesis of cardiovascular and psychosomatic diseases are very often discussed. Our studies are concerned with the analysis of 40 blue collar workers and patients (40 patients with hyperuricemia, 36 psychotherapy patients) in definite groups of age. By item analysis and multivariate statistical procedures (variance, factor and discriminant analysis) we found an overlapping effect of psychosocial factors of work and on the other hand the influence of neurotic symptoms and behaviour patterns.