WhiA, a protein of unknown function conserved among gram-positive bacteria, is essential for sporulation in Streptomyces coelicolor A3(2)

The whiA sporulation gene of Streptomyces coelicolor A3(2), which plays a key role in switching aerial hyphae away from continued extension growth and toward sporulation septation, was cloned by complementation of whiA mutants. DNA sequencing of the wild-type allele and five whiA mutations verified that whiA is a gene encoding a protein with homologues in all gram-positive bacteria whose genome sequence is known, whether of high or low G+C content. No function has been attributed to any of these WhiA-like proteins. In most cases, as in S. coelicolor, the whiA-like gene is downstream of other conserved genes in an operon-like cluster. Phenotypic analysis of a constructed disruption mutant confirmed that whiA is essential for sporulation. whiA is transcribed from at least two promoters, the most downstream of which is located within the preceding gene and is strongly up-regulated when colonies are undergoing sporulation. The up-regulation depends on a functional whiA gene, suggesting positive autoregulation, although it is not known whether this is direct or indirect. Unlike the promoters of some other sporulation-regulatory genes, the whiA promoter does not depend on the sporulation-specific sigma factor encoded by whiG.

Duplicated gene clusters suggest an interplay of glycogen and trehalose metabolism during sequential stages of aerial mycelium development in Streptomyces coelicolor A3(2)

DNA sequencing and operon disruption experiments indicate that the genes glgBI and glgBII, which code for the two developmentally specific glycogen branching enzymes of Streptomyces coelicolor A3(2) each form part of larger duplicated operons consisting of at least four genes in the order pep1-treS-pep2-glgB. The sequences of the TreS proteins are 73% identical (93% similar) to that of an enzyme that converts maltose into trehalose in Pinmelobacter, a distantly related actinomycete; and the Pep1 proteins show relatedness to the alpha-amylase superfamily. Disruptions of each operon have spatially specific effects on the nature of glycogen deposits, as assessed by electron microscopy. Upstream of the glgBI operon, and diverging from it, is a gene (glgP) that encodes a protein resembling glycogen phosphorylase from Thermatoga maritima and a homologue in Mycobacterium tuberculosis. These three proteins form a distinctive subgroup compared with glycogen phosphorylases from most other bacteria, which more closely resemble the enzymes from eukaryotes. Diverging from the glgBII operon, and separated from the pep1 gene by two very small ORFs, is a gene (glgX) encoding a probable glycogen debranching enzyme. It is suggested that most of these gene products participate in the developmentally modulated interconversion of immobile, inert glycogen reservoirs, and diffusible forms of carbon, both metabolically active (e.g. glucose-1-phosphate generated by glycogen phosphorylase) and metabolically inert but physiologically significant (trehalose).

A glgC gene essential only for the first of two spatially distinct phases of glycogen synthesis in Streptomyces coelicolor A3(2)

By using a PCR approach based on conserved regions of ADP-glucose pyrophosphorylases, a glgC gene was cloned from Streptomyces coelicolor A3(2). The deduced glgC gene product showed end-to-end relatedness to other bacterial ADP-glucose pyrophosphorylases. The glgC gene is about 1,000 kb from the leftmost chromosome end and is not closely linked to either of the two glgB genes of S. coelicolor, which encode glycogen branching enzymes active in different locations in differentiated colonies. Disruption of glgC eliminated only the first of two temporal peaks of ADP-glucose pyrophosphorylase activity and glycogen accumulation and prevented cytologically observable glycogen accumulation in the substrate mycelium of colonies (phase I), while glycogen deposition in young spore chains (phase II) remained readily detectable. The cloned glgC gene therefore encodes an ADP-glucose pyrophosphorylase essential only for phase I (and it is therefore named glgCI). A second, phase II-specific, glgC gene should also exist in S. coelicolor, though it was not detected by hybridization analysis.

Characterization of spaA, a Streptomyces coelicolor gene homologous to a gene involved in sensing starvation in Escherichia coli

A Streptomyces coelicolor gene, called spaA, homologous to the stationary phase regulatory gene rspA of Escherichia coli [Huisman and Kolter (1994) Science 265, 537-539], was cloned using the Streptomyces ambofaciens rspA homologue spa2 [Schneider et al. (1993) J. Gen. Microbiol. 139, 2559-2567] as a probe. Considerable differences in sequence and in genetic context were detected between spa2 of S. ambofaciens and spaA of S. coelicolor. A cloned internal fragment of spaA was used to direct integration of a phage vector into the spaA gene. The disruption caused delayed antibiotic production (undecylprodigiosin and actinorhodin) and led on further incubation to increased actinorhodin production at high, but not low, cell density. This phenotype was apparent only on the nutritionally poorest of three media tested. The attempted use of an integrating plasmid-based system for gene replacement of spaA gave rise to extensive deletions of adjacent chromosomal DNA.

Diagnosis and incidence of prion (Creutzfeldt-Jakob) disease: a retrospective archival survey with implications for future research

Reliable identification of Creutzfeldt-Jakob disease (CJD) in the UX has become essential following the suggestion that prion disease in cattle (BSE) might transmit, accidentally, to humans who eat contaminated beef. Recent data suggest that some cases of CJD may be clinically unrecognized; in order to examine this proposal we reviewed all cases of dementia (n = 1000+) collected in the Runwell Hospital Brain Archive between 1964 and 1990. We identified 19 cases of spongiform encephalopathy of which only 11 were diagnosed before death. These 11 individuals had a characteristic clinical history of CJD (relentless mental deterioration, prominent motor signs and death within a year). Their brains showed little or no external abnormality. In contrast, only two of the eight clinically unrecognized cases had characteristic symptoms. The remaining six presented atypically; their illness lasted 3 years or more, motor signs were much less evident, and simple dementia was the most prominent feature. The brains showed moderate or severe cerebral atrophy. Our data indicate that only about 60% of prion disease cases with pathologically typical spongiform encephalopathy were identified clinically during life. This suggests that human prion disease may be more common than previously supposed and that a further review of the epidemiology of the disease is required.

Tissue-specific glycogen branching isoenzymes in a multicellular prokaryote, Streptomyces coelicolor A3(2)

In the overtly differentiated colonies of Streptomyces coelicolor A3(2), discrete phases of glycogen synthesis are found at the vegetative/aerial mycelium boundary (phase I) and in the immature spore chains at aerial hyphal tips (phase II). We have characterized two S. coelicolor glgB genes encoding glycogen branching enzyme, which are well separated in the genome. Disruption of glgBl led to the formation of abnormal polyglucan deposits at phase I, with phase II remaining normal, whereas disruption of glgBII interfered specifically with phase II deposits, and not with those of phase I. Thus, each branching enzyme isoform is involved in a different phase of glycogen synthesis. This situation contrasts with that in simple bacteria, which typically have a single set of enzymes for glycogen metabolism, and more closely resembles that in plants.

Chromosome 14 linked familial Alzheimer's disease. A clinico-pathological study of a single pedigree

The clinical features of three affected members of a British pedigree with familial Alzheimer's disease are presented. This pedigree is one of six included in an earlier study which demonstrated linkage to chromosome 14. The individuals were investigated clinically and neuropsychologically, using both PET and MRI over a 4-year period. Further information from three deceased individuals was obtained, including histopathological confirmation of Alzheimer's disease in one case which came to autopsy. The mean age at onset for this family was 43 years. Neurological examination revealed myoclonic jerks in all cases, and one patient was documented to have seizures. Strikingly similar neuropsychological profiles were observed, characterized by an initial memory deficit with early dyscalculia and an impairment in speech production with relative absence of anomia. All individuals showed mild degrees of cerebral atrophy and two individuals had periventricular white matter lesions. PET scanning using [18F]fluorodeoxyglucose showed parieto-temporal hypometabolism in all cases and the two severely affected patients with speech production changes had additional left-sided frontal hypometabolism involving Broca's area. The least affected case initially had a more asymmetrical reduction in metabolism in the left inferior temporal and supramarginal gyri; a follow-up scan showed that this deficit had become bilateral and more severe. These clinical and neuroimaging features have not been previously reported in chromosome 14 linked pedigrees; the phenotypic variability between families suggests allelic heterogeneity at the chromosome 14 locus.

Sequence of the essential early region of phi C31, a temperate phage of Streptomyces spp. with unusual features in its lytic development

The temperate phage phi C31 is the most studied bacteriophage infecting Streptomyces spp., and has been used to develop an extensive and widely used series of cloning vectors. The sequence of 10 kb of phi C31 DNA containing most or all of the essential early genes was determined. Among the ORFs, 14 (perhaps 15) appear to be protein-coding, and these have been designated ORF1 to ORF14 and ORFX. Previously mapped transcripts appear to initiate upstream from ORFs 1, 8, 11 and 12, and within ORF3 and ORF12, in each case close to one example of the unusual ('21-mer') sequences that appear to serve as a recognition site for RNA polymerase early in the phi C31 lytic cycle [Ingham et al., Mol. Microbiol. 9 (1993) 1267-1274]. Further copies of the 21-mer are upstream from ORF2 and ORF13. There are four recognisable examples of a conserved inverted repeat sequence motif (CIR) thought to bind phi C31 repressor [Smith and Owen, Mol. Microbiol. 5 (1991) 2833-2844]. Only one CIR is closely associated with a 21-mer sequence, though three are located between known transcription units. Of all 14 ORFs, only one (ORF11) would encode a protein unmistakably resembling other known proteins; its product appears to be a DNA polymerase. Strikingly, two codons, TTA (Leu) and AGG (Arg), are absent from the 14 ORFs.

Clinical correlates of postmortem brain changes in schizophrenia: decreased brain weight and length correlate with indices of early impairment

From a postmortem study of the brains of 56 patients with schizophrenia and 56 controls, 38 cases whose clinical state had been objectively documented in life were examined to determine whether relations existed between features of the illness and postmortem findings. Decreased brain weight was significantly related (p < 0.05) to poor premorbid global function and to poor academic record, and decreased brain length was related to poorer premorbid global function (p < 0.05) and more severe negative symptoms. These relations are consistent with the view that morphological changes in the brain occur early in the course of the disease--that is, they are in some sense "developmental." An excess of "focal damage" in the patient group relative to controls was unrelated to the presence of morphological change or to features of illness, but was more common in female schizophrenic patients and was also correlated with evidence of cerebrovascular disease. This may possibly be due to a discrepancy between the groups in mode and cause of death.

Induction of beta (A4)-amyloid in primates by injection of Alzheimer's disease brain homogenate. Comparison with transmission of spongiform encephalopathy

Amyloid plaques, associated with argyrophilic dystrophic neurites, and cerebral amyloid angiopathy (CAA), but no neurofibrillary tangles, were found in the brains of three middle-aged marmoset monkeys that had been injected intracerebrally (ic) 6-7 yr earlier with brain tissue from a patient with early-onset Alzheimer's disease. Such changes were not found in the brains of three age-matched control marmosets. Immunochemically the amyloid plaques and CAA stained with antibody to beta (A4)-protein. The plaques and CAA displayed dichroic birefringence when stained with Congo red and viewed under polarized light. beta (A4)-amyloid plaques and CAA were also found in the brain of one of two marmosets injected ic 6 yr previously with brain tissue from a patient with prion disease with concomitant beta (A4)-amyloid plaques and CAA. An occasional beta (A4)-amyloid plaque was found in the brains of two of four marmosets injected ic > 4.5 yr previously with brain tissue from three elderly patients, two of whom had suspected (but untransmitted) CJD. No beta (A4)-amyloid plaques or CAA were found in six marmosets who were older than the injected animals, in four marmosets that had not developed spongiform encephalopathy (SE) having been injected several years previously with human brain tissue from three younger patients with suspected or atypical prion disease, or in 10 younger marmosets who had undergone various neurosurgical procedures. Seventeen marmosets injected in the same way with brain tissue from patients or animals with SE developed SE 17-49 mo after injection. These results suggest that beta (A4)-amyloidosis is a transmissible process comparable to the transmissibility of SE.

Epilepsy, psychosis, and schizophrenia: clinical and neuropathologic correlations

This study examines the relationship between epilepsy and psychosis. It compares clinical, EEG, and neuropathologic data from a group of subjects who had both epilepsy and psychosis with similar information from another group of patients who had epilepsy but no evidence of psychotic illness. We examined, blind to clinical diagnosis, gross and microscopic material from whole-brain specimens from 10 patients diagnosed with epilepsy plus schizophrenia-like psychosis, nine subjects diagnosed with epilepsy plus "epileptic psychosis," and 36 individuals with epilepsy (21 from an epileptic colony and 15 from the community at large) who had no history of psychosis (n = 10 + 9 + 21 + 15 = 55). We abstracted case histories without knowledge of pathologic findings. Epileptic colony patients had an earlier age at onset of seizures, while epileptic colony and epileptic psychosis patients had more frequent seizures. Epileptic individuals in the community died at a younger age than did epileptic patients in long-stay hospital care. Psychotic epileptic patients had larger cerebral ventricles, excess periventricular gliosis, and more focal cerebral damage compared with epileptic patients who had no psychotic illness. Epileptic patients with schizophrenia-like psychosis were distinguished from all other groups by a significant excess of pinpoint perivascular white-matter softenings. We found that mesial temporal sclerosis and temporal lobe epilepsy occurred with equal frequency in the psychotic and nonpsychotic groups; generalized seizures occurred more frequently in the psychotic epileptics and the epileptic colony epileptics than in the community epileptic controls.

Evidence for the experimental transmission of cerebral beta-amyloidosis to primates

The brains of three marmosets (Callithrix jacchus) injected intracerebrally 6-7 years earlier with brain tissue from a patient with early onset Alzheimer's disease were found to contain moderate numbers of amyloid plaques with associated argyrophilic dystrophic neurites and cerebral amyloid angiopathy but no neurofibrillary tangles. The plaques and vascular amyloid stained positively with antibodies to beta (A4)-protein. The brains of three age-matched control marmosets from the same colony did not show these neuropathological features. The brain of one of two marmosets injected with brain tissue from a patient with prion disease with concomitant beta-amyloid plaques and cerebral amyloid angiopathy also showed beta-amyloid plaques and angiopathy but no spongiform encephalopathy. An occasional plaque was found in the brains of two of four marmosets injected with brain tissue from three elderly patients with age-related pathology, two of whom had an additional diagnosis of possible prion disease. Neither plaques nor cerebral amyloid angiopathy were found in six other marmosets who were older than the injected animals, in 12 further marmosets who were slightly younger but who had been injected several years previously with brain tissue which did not contain beta-amyloid, or in 10 younger marmosets who had been subjected to various neurosurgical procedures. These results suggest that cerebral beta-amyloidosis may be induced by the introduction of exogenous amyloid beta-protein.

Experimental induction of beta-amyloid plaques and cerebral angiopathy in primates

Moderate numbers of amyloid plaques with associated argyrophilic dystrophic neurites and cerebral amyloid angiopathy (CAA) but no neurofibrillary tangles (NFTs) were found in the brains of 3 middle-aged common marmosets (Callithrix jacchus) inoculated intracerebrally (i.c.) 6-7 years earlier with brain tissue from a patient with early onset Alzheimer's disease. The plaques and vascular amyloid stained positively with antibodies to beta (A4)-protein. The brains of 3 age-matched control marmosets from the same colony did not show these neuropathological features. beta-amyloid plaques and CAA (but no spongiform encephalopathy) were also found in the brain of a marmoset inoculated with brain tissue from a patient with prion disease with concomitant beta-amyloid plaques and CAA. An occasional beta-amyloid plaque was found in the brains of two marmosets inoculated with brain tissue from elderly patients. No beta-amyloid plaques nor CAA were found in 6 other marmosets who were older than the inoculated marmosets, 10 further marmosets who were slightly younger but who had been inoculated several years previously with brain tissue which did not contain beta-amyloid, and 10 younger marmosets who had been subjected to various neurosurgical procedures. These results suggest that beta-amyloidosis is a transmissible process.

Multiple novel promoters from the early region in the Streptomyces temperate phage phi C31 are activated during lytic development

Evidence is presented that transcription of most of the early genes in the Streptomyces coelicolor A3(2) phage phi C31 is from a series of unusual promoters that depend on a function expressed early in the phi C31 lytic cycle. Primer extension analysis on the 5' ends of three early mRNAs, from samples prepared 10 min after induction of a thermosensitive phi C31 lysogen, showed that the 5' ends all mapped close to highly similar sequences, which are proposed to be an important part of phage-specific promoters. In a shotgun cloning experiment, a fragment containing one of these sequences strongly activated transcription of the xyIE reporter gene in plaques of a phi C31-derived promoter-probe vector. Another of the sequences was inserted into a xyIE-containing promoter-probe plasmid vector, and promoted xyIE expression only when the host was supporting the lytic cycle of phi C31. This suggested that a transcription factor needed for activity of the promoters was present only in phi C31-infected cells. Examination of published and unpublished phi C31 sequence data revealed several more sequences that closely resemble the conserved region of the characterized promoters. Most of these are found in positions close to apparent transcription start sites mapped previously by low-resolution S1 mapping. An overall consensus sequence for the conserved region suggests a general organization (though not a primary sequence) resembling that of promoters recognized in other bacteria by the sigma 54 form of RNA polymerase.

Ubiquitination as a probe for neurodegeneration in the brain in schizophrenia: the prefrontal cortex

Abnormalities in brain structure and brain function have been described in schizophrenia. It is not yet known whether these are caused by an abnormality of brain development, some form of birth injury, or a neurodegenerative process. Using immunocytochemical methods and a marker for neurodegeneration (ubiquitin), we examined an area of prefrontal cortex from elderly schizophrenic and control subjects for the presence of ubiquitin-positive degeneration products. There was no statistical difference in the degree of ubiquitination between the control and the patient samples. The findings provide no evidence to support a neurodegenerative process.

Quantitative differences in the deposition of beta A4 protein in the sulci and gyri of frontal and temporal isocortex in Alzheimer's disease

The distribution of beta-amyloid protein (beta A4) in the frontal and temporal isocortex of 14 Alzheimer's disease brains was examined using a combination of immunohistochemistry and computer image analysis. The area of cortex covered by beta A4 deposits was determined and expressed as a percentage of the total cortical grey matter area in each field of interest. Significantly more beta A4 was found in the grey matter of the sulci as compared to that of the gyral crests in both the frontal and the temporal lobes (P less than 0.05). Furthermore, in each case, greater quantities of beta A4 were observed in the frontal rather than the temporal lobes. This apparent differential vulnerability is likely to reflect underlying anatomical connections or perhaps differences in cell packing density and appears to strengthen the case for an anatomical basis for the spread of the disease pathology.

Phage Vectors that Allow Monitoring of Transcription of Secondary Metabolism Genes in Streptomyces

We describe a bacteriophage phi C31-based system that permits the transcriptional fusion of the convenient reporter gene xylE to chromosomally located promoters in Streptomyces hosts. Applicability of the system to genes for secondary metabolism is demonstrated in an experiment showing that transcription of genes for actinorhodin production in Streptomyces coelicolor A3(2) depends on a transfer RNA gene (bldA) for the rare UUA codon. Two other phi C31::xylE vectors are described that allow detection of promoter activity away from their natural location, either at single copy in a prophage or during lytic infections in plaques.

Discovery of an insertion sequence, IS116, from Streptomyces clavuligerus and its relatedness to other transposable elements from actinomycetes

We have identified an insertion sequence, IS116, present in Streptomyces clavuligerus at one copy per genome. The element was discovered as a 1.4 kb insertion into the multicopy plasmid pIJ702 after propagation in S. clavuligerus. The nucleotide sequence of IS116 and the flanking sequences from pIJ702 have been determined. The junctions with pIJ702 show no target site duplication and there are no inverted repeats at the ends of the element. One putative coding open reading frame of 1197 bp was identified which would code for a protein product of 399 amino acids. This protein resembles deduced integrase/transposase proteins specified by three other transposable elements of actinomycetes: IS110 and the mini-circle from Streptomyces coelicolor A3(2), and--most particularly--IS900 of Mycobacterium paratuberculosis. Two regions that are relatively conserved among these gene products show features found in similar positions in many reverse transcriptases. IS116 and IS900 are also closely similar in their general organization and (apparently) in their insertion site specificity, whereas IS110 and the mini-circle are quite different in these features.

Schizophrenia and the brain: a prospective clinico-neuropathological study

The neuropathological results from a prospective, systematically assessed, series of 56 schizophrenic patients and 56 age- and sex-matched normal controls have been presented. When compared with the normal controls, the brains of the schizophrenic subjects showed a significant reduction in brain weight and brain length with a concomitant increase in ventricular size. (All findings relate to measurements made after formalin fixation). In addition, the brains of the schizophrenic patients contained significantly more non-specific focal pathology and fibrillary gliosis than the controls. After exclusion of cases with moderate and severe Alzheimer-type change, cerebro-vascular disease and all forms of focal pathology, the structural brain changes (i.e. decrease in brain weight and brain length) continued to distinguish the schizophrenia group from the controls. Furthermore, an analysis of the clinical data showed that the structural brain changes were correlated in the schizophrenic patients with a measurement of pre-morbid function. The findings and their possible aetiological implications have been discussed.

Notes from the graveyard: neuropathology and schizophrenia

Schizophrenia is commonly regarded as a 'functional' psychosis, the implication being that the delusions, hallucinations and cognitive impairment characteristic of the disease have no organic basis. This view is due in no small way to the failure of pathologists to find convincing pathological changes associated with the disease in the first seven decades of the century. Over the last 10 years things have changed considerably. Recent CT and MRI scan studies have provided convincing evidence of significant ventricular enlargement in the brains of schizophrenics and post-mortem studies have shown that schizophrenic brains are about 6% lighter than controls and have a reduced volume and reduced antero-posterior length. Planimetric studies on post-mortem material and a recent MRI study show that medial temporal lobe structures (parahippocampal gyrus, hippocampus and amygdala) are preferentially affected. Although other brain regions (e.g. cingulate gyrus, frontal cortex) also show alterations they appear to be 'downstream' from the regions primarily affected. Morphological studies show that there is a loss of neurons from medial temporal lobe structures and indicate irregularities in their cytoarchitectonic arrangement. The alterations in structure are not associated with degenerative, inflammatory, or abnormal vascular processes. There has been much debate as to the possible causes of the structural changes and whether they are limited to particular 'types' or sub-groups of schizophrenics. At present it seems simpler to suppose that all schizophrenics have a degree of structural abnormality which may differ in degree but not in kind. It has been proposed that the changes in brain structure in schizophrenia are the result of an anomaly of brain development. In the last year CT and MRI studies have shown that ventricular enlargement precedes clinical symptoms and is not progressive. These studies support the developmental interpretation. Future studies will need to focus on (a) the mechanisms (probably genetic) which can cause such developmental anomalies, (b) the neurochemical perturbations occurring as a result of such anomalies and (c) how both relate to clinical symptoms.

Schizophrenia as an anomaly of development of cerebral asymmetry. A postmortem study and a proposal concerning the genetic basis of the disease

Schizophrenia is associated with structural changes (eg, a mild degree of ventricular enlargement) in the brain, although whether these precede onset of illness or progress with episodes is not established. In a postmortem study, we find that ventricular enlargement affects the posterior and particularly the temporal horn of the lateral cerebral ventricle. By comparison with controls and with patients suffering from Alzheimer-type dementia (in which there is also temporal horn enlargement), the change is highly significantly selective to the left hemisphere. This deviation was not accompanied by an increase in glial cell number (examined chemically by assay of diazepam-binding inhibitor immunoreactivity and microscopically by density of staining with the Holzer technique). The findings are consistent with the view that schizophrenia is a disorder of the genetic mechanisms that control the development of cerebral asymmetry.

The developmental fate of S. coelicolor hyphae depends upon a gene product homologous with the motility sigma factor of B. subtilis

In the mycelial prokaryote S. coelicolor, whiG is a gene dispensable for growth but needed for the earliest stages of spore formation in aerial hyphae. Nucleotide sequencing indicates that whiG encodes an RNA polymerase sigma factor highly similar to the motility sigma factor (sigma 28) of B. subtilis. High copy number of an intact whiG gene caused sporulation in vegetative hyphae that are usually fated to lyse without sporulating. However, the introduction of many copies of a sigma 28-dependent promoter from B. subtilis into S. coelicolor reduced sporulation, suggesting partial sequestration of the whiG gene product by the foreign promoter sequences. We propose that the level of whiG sigma factor is crucial in determining the developmental fate of hyphae.

Brain amino acid concentrations and Ca2+-dependent release in intractable depression assessed antemortem

The concentrations of 3 putative neurotransmitters (glutamate, aspartate and gamma-aminobutyrate), 4 related amino acids and 5 non-transmitter-related amino acids have been measured in neurosurgical samples (frontal cortex) from patients with intractable depression and controls. In addition, the glutamate receptor agonist 2-amino-4-sulpho-butanoic acid (homocysteic acid) has been identified in human brain and measured in these samples. There were no changes in the concentrations of amino acids in depressed patients compared to control with the exception of aspartic and homocysteic acids which were elevated in a sub-group of patients with depression compared to control. The Ca2+-dependent release (K+-stimulated) of putative neurotransmitters has been demonstrated for the first time from brain tissue of depressed patients. Glutamate release was unaltered from the control value. Aspartate values showed unexplained variability but it's release and that of gamma-aminobutyrate were elevated in some depressed subjects. These results do not support the hypothesis of reduced amino acid function in depressive illness.

The cerebral vasculature in dementia pugilistica

The brains of 22 ex-boxers were examined histologically to determine the frequency of recent or old haemorrhage. Four boxers had died from an acute intracerebral bleed, usually soon after a boxing bout. Seven of the other 18 showed evidence of previous perivascular haemorrhage, as detected by Perls' ferrocyanide test for iron, and a similar number showed minor degrees of meningeal or subpial siderosis, consistent with previous meningeal bleeding; cerebellar siderosis was present in six cases. Seventeen of the 22 boxers showed evidence of recent or past haemorrhage. Control material showed an incidence of 11% for perivascular iron deposition and only 4% for minor degrees of meningeal siderosis.

Nucleotide sequence of IS110, an insertion sequence of Streptomyces coelicolor A3(2)

The nucleotide sequences of the Streptomyces transposable element IS110 and its insertion site in the DNA of a derivative of the temperate phage luminal diameter C31 were determined. The element is inserted about 460 bp from the right-hand end of luminal diameter C31 DNA, in a region of apparently non-coding DNA. The target site (in a run of seven C residues) is within an 11 bp sequence homologous with one end of IS110. The inserted element is flanked by runs of 11 and 15 C residues which form part of more extensive regions of homology between the left and right junction regions. Imperfect inverted repeats (10 matches out of 15 bp) are present near (but not at) the ends of IS110. The whole IS110 element contains about 1550 bp of which 71% are G-C bp. One major potentially protein-coding region (ORF 1215) was detected, of 1215 bp, the product of which, a presumptively soluble protein of MR 43,563, was not overtly related to any entry in a protein sequence database. A smaller open reading frame (ORF 330) was tentatively identified in the opposite strand of the ORF 1215 region.

The isolation of a peptide from the catalytic domain of Bacillus stearothermophilus tryptophyl-tRNA synthetase. The interaction of Brown MX-5BR with tyrosyl-tRNA synthetase

Tryptophyl-tRNA synthetase is irreversibly inactivated by Procion Brown MX-5BR with an apparent dissociation constant (KD) of 8.8 microM and maximum rate of inactivation k3 0.192 s-1. The specificity of the interaction is supported by two previously reported observations. Firstly, Brown MX-5BR inactivation of tryptophyl-tRNA synthetase is inhibited by substrates, and secondly, the animated derivative of Brown MX-5BR is a competitive inhibitor of tryptophyl-tRNA synthetase with a Ki of 2 X 10(-4) M with respect to both tryptophan and ATP. Tryptic digestion of the dye-affinity-labelled enzyme and subsequent resolution of the peptides by h.p.l.c. yielded one major dye-peptide peak. Amino acid sequence analysis resulted in the identification of the dye-binding domain centred on lysine-178. Tyrosyl-tRNA synthetase is also inactivated by Procion Brown MX-5BR, and this inactivation is prevented by ATP but not by tyrosine. The interaction of tyrosyl-tRNA synthetase with hydroxylated Brown MX-5BR exhibited non-competitive kinetics with respect to the amino acid-binding site and competitive kinetics against ATP with a Ki of 6 X 10(-6) M.

The glucose kinase gene of Streptomyces coelicolor and its use in selecting spontaneous deletions for desired regions of the genome

A number of deletions in the glucose kinase (glk) region of the Streptomyces coelicolor chromosome were found among spontaneous glk mutants. The deletions were identified by probing Southern blots of chromosomal DNA from glk mutants with cloned glk DNA. The deletions ranged in size from 0.3 kb to greater than 2.9 kb. When cloned glk DNA was introduced on a phi C31 phage vector into a glk mutant that contained a deletion of the entire homologous chromosomal glk region, glucose kinase activity was detected in extracts of these cells. The entire coding information for at least a subunit of glucose kinase is therefore present on the cloned glk DNA. The 0.3 kb glk chromosomal deletion was used to demonstrate that transfer of chromosomal glk mutations on to the phi C31::glk phage could occur by recombination in vivo. Since glk mutations frequently arise from deletion events, a method was devised for inserting the cloned glk DNA at sites in the chromosome for which cloned DNA is available, and thus facilitating the isolation of deletions in those DNA regions. phi C31::glk vectors containing a deletion of the phage att site cannot lysogenize S. coelicolor recipients containing a deletion of the glk chromosomal gene unless these phages contain S. coelicolor chromosomal DNA. In such lysogens, the glk gene becomes integrated into the chromosome by homologous recombination directed by the chromosomal insert on the phage DNA. In appropriate selective conditions, mutants which contain deletions of the glk gene that extend into the adjacent host DNA can be easily isolated. This method was used to insert glk into the methylenomycin biosynthetic genes, and isolate derivatives with deletions of host DNA from within the prophage into the adjacent host DNA. Phenotypic and Southern blot analysis of the deletions showed that there are no genes essential for methylenomycin biosynthesis for at least 13 kb to the left of a region concerned with negative regulation of methylenomycin biosynthesis. Many of the deletions also removed part of the phi C31 prophage.

Properties of in vitro recombinant derivatives of pJV1, a multi-copy plasmid from Streptomyces phaeochromogenes

The 10.8 kb plasmid pJV1, isolated from Streptomyces phaeochromogenes, has a high copy number (about 150) and a broad host range among Streptomyces spp. Several pJV1 derivatives carrying the thiostrepton resistance gene (tsr) of S. azureus were made. One derivative, pWOR191, was shown to promote its own transfer and to mobilize chromosomal markers in S. lividans. Another derivative, pWOR109, was non-transmissible. Deletion in vitro of a segment of pWOR109 gave pWOR120 (5.6 kb), which has single BamHI and Bg/II sites shown to be capable of accepting 'foreign' DNA such as a previously cloned S. antibioticus DNA fragment encoding tyrosinase, giving vectors (pWOR125, pWOR126) with properties resembling the well-established multicopy vector pIJ702. Shuttle vectors capable of functioning in both S. lividans and Escherichia coli were also constructed. The region of pJV1 essential for replication and maintenance was localized to a 2.5 kb segment. Stable maintenance of pWOR109 and pWOR120 was observed in the presence of derivatives of pIJ101, the progenitor of pIJ702.

Resistance, regulatory and production genes for the antibiotic methylenomycin are clustered

At least 17 kb of DNA from the large unisolatable Streptomyces coelicolor A3(2) plasmid SCP1 are concerned with methylenomycin biosynthesis. Mutational cloning analysis, using insert-directed integration of att site deleted phage vectors into an SCP1-containing host, provided evidence of two large transcription units, of at least 6.6 kb and 9.5 kb. At the leftmost apparent end of the larger (left-hand) transcription unit is a region apparently involved in negative regulation of methylenomycin biosynthesis: when fragments from this region were used to direct phage integration, marked overproduction of methylenomycin resulted. The methylenomycin resistance determinant is located at the rightmost end of this same transcription unit. Hybridisation analysis with 13 kb of the cloned mmy region showed that it was closely similar to a segment of pSV1, a plasmid that specifies methylenomycin biosynthesis in S. violaceus-ruber SANK 95570.

New derivatives of the Streptomyces temperate phage phi C31 useful for the cloning and functional analysis of Streptomyces DNA

The thiostrepton resistance gene (tsr) of Streptomyces azureus, and a synthetic oligonucleotide adapter sequence, were introduced into the DNA of attP-site-deleted phage phi C31-based cloning vectors. The DNA of two of the new derivatives, KC515 and KC516, contains single sites for the enzymes BamHI, BglII, PstI, PvuII, SstI (two sites close together) and XhoI, available for the insertion of DNA of up to 4 kb. The two vectors also contain a cloned, promoterless viomycin phosphotransferase gene (vph) from Streptomyces vinaceus. When an internal segment of the Streptomyces coelicolor glycerol (gyl) operon was inserted at the appropriate position and in the correct orientation next to vph, it could bring about in vivo recombination leading to fusion of vph of the chromosomally located gyl operon, resulting in glycerol-regulated expression of viomycin resistance. Two other new phi C31 derivatives, KC505 and KC518, are PstI and BamHI replacement vectors, respectively, for 2-8-kb DNA fragments, and allow simple screening for the presence of inserted DNA.

The complete nucleotide sequence of the Pseudomonas gene coding for carboxypeptidase G2

The complete nucleotide sequence of the Pseudomonas chromosomal gene coding for the enzyme carboxypeptidase G2 (CPG2) has been determined. The nucleotide sequence obtained has been confirmed by comparing the predicted amino acid sequence with that of randomly derived peptide fragments and by N-terminal sequencing of the purified protein. The gene has been shown to code for a 22 amino acid signal peptide at its N-terminus which closely resembles the signal peptides of other secreted proteins. An alternative 36 amino acid signal peptide which may function in Pseudomonas has also been identified. The codon utilisation of the gene is influenced by the high G + C (67.2%) content of the DNA and exhibits a 92.8% preference for codons ending in G or C. This unusual codon preference may contribute to the generally observed weak expression of Pseudomonas genes in Escherichia coli. A region of DNA upstream of the structural gene has also been sequenced and a ribosome binding site and two putative promoter sequences identified.

Genetic mapping, cloning and physiological aspects of the glucose kinase gene of Streptomyces coelicolor

Glucose kinase in Streptomyces coelicolor has a molecular weight of about 110,000. In crude extracts, the enzyme exhibited apparent Km values of 0.20 mM for ATP, 0.27 mM for glucose, and 2.2 mM for the glucose analogue 2-deoxyglucose. Mutations (glk) to 2-deoxyglucose-resistance, which greatly reduce glucose kinase activity and result in relief of glucose repression of utilisation of various carbon sources, were mapped between proA and hisA in the S. coelicolor linkage map. Glucose kinase activity, 2-deoxyglucose-sensitivity, glucose utilisation and glucose repression, were all restored to glk mutants by a 3.5 kb DNA fragment cloned from S. coelicolor into a phage vector (phi C31 KC515), and by larger (10-30 kb) fragments cloned into a low copy number plasmid vector (pIJ916). The glk gene was further localised to a 2.9 kb BclI fragment of the cloned DNA by sub-cloning. Part or all of this fragment was present in each of five primary plasmid clones tested.

Amino acid sequence homology between rat and human C-reactive protein

The rat serum protein that undergoes Ca2+-dependent binding to pneumococcal C-polysaccharide and to phosphocholine residues, and that is evidently a member of the pentraxin family of proteins by virtue of its appearance under the electron microscope, has been variously designated as rat C-reactive protein (CRP) [de Beer, Baltz, Munn, Feinstein, Taylor, Bruton, Clamp & Pepys (1982) Immunology 45, 55-70], 'phosphoryl choline-binding protein' [Nagpurkar & Mookerjea (1981) J. Biol. Chem. 256, 7440-7448] and rat serum amyloid P component (SAP) [Pontet, D'Asnieres, Gache, Escaig & Engler (1981) Biochim. Biophys. Acta 671, 202-210]. The partial amino acid sequence (45 residues) towards the C-terminus of this protein was determined, and it showed 71.7% identity with the known sequence of human CRP but only 54.3% identity with human SAP. Since human CRP and SAP are themselves approximately 50% homologous, the level of identity between the rat protein and human SAP is evidence only of membership of the pentraxin family. In contrast, the much greater resemblance to human CRP confirms that the rat C-polysaccharide-binding/phosphocholine-binding protein is in fact rat CRP.

The glycerol utilization operon of Streptomyces coelicolor: genetic mapping of gyl mutations and the analysis of cloned gylDNA

Glycerol-3-phosphate dehydrogenase (gylB) mutations (which cause glycerol sensitivity), and presumed glycerol kinase (gylA) and/or regulatory mutations eliminating both glycerol-3-phosphate dehydrogenase and glycerol kinase activities, map close to the argA locus of Streptomyces coelicolor A3(2). Using the plasmid vector pIJ702 and restriction enzymes BglII and SstI, extensively overlapping S. coelicolor DNA fragments of 2.74 kb and 2.84 kb were isolated, either of which could restore the wild-type phenotype to gylB and some gylA mutants. Genetic and biochemical analyses of mutants carrying the cloned gyl DNA suggested that a functional gyl promoter had not been cloned, and that restoration of the Gyl+ phenotype was achieved by recombination between the cloned and chromosomal gyl DNA sequences. After subcloning parts of this DNA into the phage vector phi C31 KC400, "gene disruption" analysis was carried out, which confirmed the absence of the gyl promoter, and indicated that a polycistronic mRNA traverses gylA and then gylB.

Mutational cloning in Streptomyces and the isolation of antibiotic production genes

An attachment site-deleted derivative, phi C31KC400, of the Streptomyces temperate phage phi C31 was used to clone fragments of the genetic determinants (mmy) for the biosynthesis of an antibiotic, methylenomycin A. The vector carries a cloned viomycin resistance gene (vph), and can transduce a recipient to viomycin resistance when DNA sequences are common to the phage and the recipient: the phage integrates into the recipient's genome through a Campbell type of recombination at the site of the homology. For the cloning of mmy DNA, the homology was provided by the in vitro insertion into the vector of DNA from a methylenomycin A-producing streptomycete. Clones carrying mmy DNA could integrate into a methylenomycin-producing recipient's mmy genes, sometimes disrupting their expression: thus a search of viomycin-resistant transductants for methylenomycin non-producing derivatives identified lysogens which spontaneously released phi C31 phages carrying mmy DNA. Some of these lysogens participated in methylenomycin co-synthesis with previously isolated mmy mutants. At least 7 kb of mmy DNA was identified among the clones. Screening for mmy non-producers was simplified by exploiting the presence of the mmy genes on the (albeit unisolable) plasmid, SCP1. In the course of the experiment, SCP1, a low copy number plasmid in its primary host S. coelicolor A3(2), was shown to have a copy number of about 30 in the single S. parvulus SCP1+ transconjugant strain tested, and a molecular size probably greater than 200 kb.

The restriction mapping of c gene deletions in Streptomyces bacteriophage phi C31 and their use in cloning vector development

In addition to 20 previously mapped restriction sites in the DNA of phi C31, we have determined eight sites for SphI, four for EcoRV, and two for SstII; there are none for BglII or SstI. Nine sites were in a 12-kb segment of DNA containing no previously mapped sites. Deletions causing clear-plaque morphology were located in this part of the DNA, in a 3-kb interval between an EcoRV and an SphI site at the centre of the DNA molecule. One of the deletions (delta C3) was obtained in a previously described phi C31c+::vph (viomycin phosphotransferase) derivative containing two PstI sites separated by 3.9-kb of inessential DNA. After in vitro PstI treatment, plaque-forming phages lacking the 3.9-kb fragment were obtained from the c+ phage but not from its delta C3 derivative. Thus a 36.2-kb genome, but not one of 34.4 kb, was able to give infectious virions. PstI-generated DNA fragments of up to 8 kb can be inserted in vitro into the delta C3 derivative with retention of the vph selective marker. With the insertion of a 6.03-kb PstI fragment of plasmid SCP2, the latter phage became a potential vector (with loss of vph) for BamHI-generated DNA fragments of up to 9 kb. In the course of this work, several ClaI sites in phi C31::pBR322 bifunctional replicons were shown to be lost when the DNA was propagated in a dam+ Escherichia coli strain. This will allow the use of such replicons for the cloning of ClaI-generated DNA fragments of up to 6.7 kb.

Large-scale purification of enzymes

Many standard procedures for the purification of proteins in the laboratory do not readily lend themselves to scaling up, whereas, on the other hand, some techniques relatively unsatisfactory in the laboratory are much more effective on a large scale. When producing gram or kilogram quantities of enzymes for use over an extended period, the storage properties and general tractability of the purified products become increasingly important. Hence enzymes from thermophilic sources frequently have advantages over those from mesophiles. The possible economic advantages of simultaneous large-scale multi-enzyme isolation over separate individual enzyme purifications are evaluated. Batchwise adsorption and elution from ion-exchange celluloses frequently replace traditional precipitation techniques in the early stages of a large-scale purification. Dialysis is replaced by concentration, dilution and reconcentration with the use of hollow-fibre ultrafiltration equipment. Antiphonally direct scaling-up of column chromatographic procedures is usually possible. Modifications to column geometry to maximize flow rates are often desirable but purification factors and recoveries comparable with those obtained on the laboratory scale can be achieved relatively easily. Classical affinity chromatographic techniques have not proved so amenable to large-scale work, mainly because of the enormous expense and rather short life of the matrices. However, the quasi-affinity chromatography afforded by the triazine dye conjugates has proved of great benefit. The materials are cheap to prepare. The coupling procedures are both simple and rapid and do not involve the use of noxious chemicals such as cyanogen bromide. Moreover the triazine linkage is more stable under a variety of conditions than the isourea formed in cyanogen bromide coupling. Considerable further exploitation of these versatile matrices is expected.

The tyrosyl-tRNA synthetase from Escherichia coli. Complete nucleotide sequence of the structural gene

The structural component of the tyrS gene of Escherichia coli, comprising 1269 base pairs, has been fully sequenced by the combined M13/dideoxychain termination approach. The gene has a codon usage pattern which is typical of highly expressed proteins and similar to other Escherichia coli aminoacyl-tRNA synthetase genes. Peptide purification and sequencing has been used to locate the N-terminus and to provide confirmation of 95% of the translated protein sequence. This latter yields on Mr of 47,403 for the Escherichia coli tyrosyl-tRNA synthetase, and reveals considerable homology with the primary structure of the analogous enzyme isolated from Bacillus staerothermophilus.

Affinity labelling of enzymes with triazine dyes. Isolation of a peptide in the catalytic domain of horse-liver alcohol dehydrogenase using Procion blue MX-R as a structural probe

Horse liver alcohol dehydrogenase is irreversibly inactivated by Procion blue MX-R, a dichlorotriazinyl structural analogue of Cibacron blue F3G-A, with over 90% loss of activity within 30 min at pH 8.5 and 37 degrees C at a reactive dye concentration of 1 mM and enzyme subunit concentration of 5 microM. Methoxylated Procion blue MX-R does not inactivate the enzyme. The inactivation of horse liver alcohol dehydrogenase by Procion blue MX-R is competitively inhibited by the pyridine nucleotides NAD+ and NADH. Quantitatively inhibited horse liver alcohol dehydrogenase contains 1 mol dye/mol subunit of Mr 40 000. Chymotryptic digestion and resolution of the peptides by reverse-phase high-performance liquid chromatography yields a single blue peptide which on sequencing and analysis yields an amino acid sequence of: (formula; see text) with the affinity label, Procion blue MX-R, unambiguously identified as being attached to the thiol side chain of Cys-174 in the catalytic domain of the enzyme. The specific active-site-directed reaction of Procion blue MX-R with horse liver alcohol dehydrogenase is interpreted in terms of the known crystallographic structure of the enzyme.

Methionyl-tRNA synthetase from Escherichia coli. Primary structure of the active crystallised tryptic fragment

A 3300-base segment of Escherichia coli chromosomal DNA, cloned into pBR322, will complement a methionine auxotroph in which the lesion is a defective methionyl-tRNA synthetase with a much reduced affinity for methionine. Crude extracts of these transformants contain elevated levels of a protein which has a subunit molecular weight of 66 000, methionyl-tRNA synthetase aminoacylation activity in vitro and which cross-reacts with anti-(methionyl-tRNA synthetase) antibodies. This polypeptide is very slightly larger than the well-characterised and crystallised tryptic fragment of methionyl-tRNA synthetase. A DNA sequence of 1750 residues at one end of the cloned insert codes for a non-terminated open reading frame in which we can locate a large number of methionyl-tRNA synthetase tryptic and chymotryptic peptides. We have also sequenced 300 nucleotides upstream of this coding segment where we find a large invert repeat in the putative methionyl-tRNA synthetase promoter region.

The interaction of tryptophanyl-tRNA synthetase with the triazine dye Brown MX-5BR

Brown MX-5BR specifically and irreversibly inactivates tryptophanyl-tRNA synthetase from Bacillus stearothermophilus at pH 8.5. The enzyme is protected from inactivation by the substrates tryptophan and ATP and to lesser extents by ADP, AMP, the product inorganic pyrophosphate and other nucleotides such as GTP. The Kd of the pure reactive dye for the enzyme was measured to be 6.7 X 10(-6) M. The Km values of the two substrates tryptophan and MgATP were found to be 1 x 10(-5) M and 5 x 10(-5) M respectively. The aminated dye is a competitive inhibitor of tryptophanyl-tRNA synthetase with respect to both tryptophan and MgATP with Ki values of 2 x 10(-4) M against both substrates. The use of this dye as an active-site-directed affinity label is discussed.

The expression of Streptomyces and Escherichia coli drug-resistance determinants cloned into the Streptomyces phage phi C31

Lysogens obtained by infecting Streptomyces albus G with a phi C31-pBR322 chimaeric prophage or its delta W12 deletion derivative had increased tetracycline resistance. The ability of the delta W12 derivative to transduce tetracycline resistance was inactivated by inserting a viomycin resistance determinant (vph) into the BamHI site of the pBR322 tet gene, and restored by excising the vph gene. Another deletion mutant (delta W17) of the chimaera, carrying an intact tet gene, was normally unable to transduce tetracycline resistance. This inability was correlated with the finding, by Southern hybridisation analysis, that the att site required for insertion of phi C31 prophage into the host chromosome was located within the delta W17 deletion. Use of phi C31 lysogenic recipient permitted the integration of the att-deleted phage, presumably by homologous recombination, giving tetracycline-resistant double lysogens. This technique was extended to S. coelicolor A3(2) in the detection of derivatives of the att-deleted phage into which a thiostrepton-resistance determinant (tsr) had been inserted in vitro. Phage released from double lysogens were mainly recombinants. One such recombinant is a PstI vector for DNA cloning, able to accommodate up to 6 kb of introduced DNA.

Dispensable sequences and packaging constraints of DNA from the Streptomyces temperate phage phi C31

Deletion mutants of the temperate Streptomyces phage phi C31 were selected by two methods: resistance to the chelating agent sodium pyrophosphate, and plating of a phi C31::pBR322 hybrid phage on Streptomyces albus G to obtain large plaque mutants. The deletions defined a 7.7 kilobase (kb) segment of the phi C31 genome which is inessential for plaque formation, in addition to a shorter segment including the repressor gene. Analysis of deletions and insertions suggested that the minimum size of the phi C31 genome allowing plaque formation is 37.5 kb (91% of the wild-type length of 41.2 kb), and the maximum is at least 42.4 kb (103%). These results indicate that it should be possible to introduce up to 10 kb of foreign DNA into a suitably developed phi C31 vector.