Protein anatomy: functional roles of barnase module

Globular proteins are composed of several modules that are contiguous polypeptide segments of compact conformation. Module boundaries are closely correlated with the intron positions of genes that encode proteins. The modules may thus have a one-to-one correspondence with exons in primordial genes. They may also be vestiges of polypeptide segments that initially appeared as primordial proteins in prebiological evolution. Clarification as to whether modules disconnected from one another have functional potentiality may validate these possibilities. Thus, in this study, each module of a protein was synthesized and assessed for functional potentiality. For this purpose, barnase, a bacterial ribonuclease, was decomposed into six modules (M1-M6), which were examined to determine whether they have an affinity for RNA and RNase activity. M2, M3, and M6, all of which form a shallow but wide cavity for RNA binding in native barnase, were found to bind to RNA and to possess RNase activity. However, M1 and M5, which support the other modules from the back side, and M4 did not bind to RNA and had no RNase activity. Protein modules with catalytic functions are described in this paper for the first time. That some modules of barnase possess catalytic activity indicates that protein modules may possibly have functioned as primitive catalysts in prebiological evolution.

Protein anatomy: spontaneous formation of filamentous helical structures from the N-terminal module of barnase

This paper reports the conformation of the N-terminal module (24 amino acid residues) of barnase in aqueous solution. This module contains the first of three helices in the intact protein. Circular dichroism spectra showed the peptide fragment to have a predominantly random coil structure immediately following dissolution in aqueous solution and to be gradually converted to a helical structure at 5 degrees C. This was mediated by aggregation, and an electron micrograph indicated the aggregate to be comprised of filamentous helical structures. Scanning tunneling microscopy showed the filamentous structures to be made up of protofilamentous structures containing many disks apparently stacked on top of each other. A monomer of the peptide predominantly took on a random coil conformation in aqueous solution and the multimer, a stable helical structure. A local amino acid sequence would thus appear to determine the secondary structure corresponding to that in a native protein but stability to be governed by other factors such as tertiary interactions. Helical wheel representation indicated the peptide fragment to have the features of an amphiphilic helix. Hydrophobic burial may provide the driving force for producing a stable helical structure in aqueous solution.

[Immunohistochemical study of proteoglycans and collagens in the mouse cochlear duct]

Immunohistochemical studies of proteoglycans and collagens (type I and type IV) in the cochlear duct, and of the effects of cisplatin (CDDP), were performed. In cells of the organ of Corti and in the middle layer of the stria vascularis, heparan sulfate proteoglycan (HSPG) and collagens (type I and IV) or collagen-like substances were found. HSPG in these locations appeared to play important roles in the production of auditory sense. The tectorial membrane contained HSPG and collagens (type I and IV). However, no data supporting the concept that elements of the tectorial membrane are derived from interdental cells was obtained. In the basilar membrane, no HSPG, chondroitin sulfate (Chs), or collagens (type I and IV) were detected. The unique structures containing these substances reacted strongly with anti-HS (heparan sulfate), anti-HSPG-CP (core protein) and anti-collagen (type I and IV) antibodies that developed in the middle layer of the stria vascularis after the administration of CDDP. However, no change was observed in the tectorial membrane, the spiral prominence, the basilar membrane, or the spiral limbus. The decrease in HSPG in cells of the organ of Corti, and the changes in the stria vascularis, may help solve the well known contradiction between the severity of morphological damage and of the hardness of hearing.

15-Deoxyspergualin "rescue therapy" for methylprednisolone-resistant rejection of renal transplants as compared with anti-T cell monoclonal antibody (OKT3)

A randomized trial with OKT3, an anti-T cell monoclonal antibody or with 15-deoxyspergualin against methylprednisolone-resistant rejection crisis was performed in 25 posttransplant patients immunosuppressed with prednisolone and cyclosporine. At least temporary reversal of rejection was observed in 58.3% of patients treated with 15-deoxyspergualin. This reversal rate may be quite comparable to 61.5% seen in patients treated with OKT3. Adverse effects with 15-deoxyspergualin were related to bone marrow suppression, while those with OKT3 were pyrexia, gastrointestinal symptoms, and herpes infection. In contrast to OKT3, which may act by modulating T cell surface antigen, 15-deoxyspergualin may be effective somewhere in the later stages of the rejection cascade.

Identification of an amino acid residue involved in the substrate-binding site of rat liver uricase by site-directed mutagenesis

Computer analysis has shown that a conserved amino acid sequence (Leu 160 to Lys 164) of rat liver uricase is also present in other enzymes with purine substrates. The significances of the amino acids in this sequence were studied by site-directed mutagenesis. Replacement of Lys 164 by Glu or Ile resulted in loss of uricase activity and decrease in binding of the competitive inhibitor xanthine. The far ultraviolet circular dichroic spectra of the mutant uricases were identical to that of the wild type protein, indicating that the replacement of Lys 164 by other amino acids did not result in serious modification of the conformation of uricase. These findings suggest that this amino acid is involved in the substrate-binding site of the enzyme.

[Effect of angiotensin II(AII) on peritoneal transport during peritoneal dialysis in rat]

Ultrafiltration volume (UFV) in peritoneal dialysis is expressed as the difference between net transcapillary ultrafiltration (TCUF) and lymphatic absorption (LA) in peritoneal cavity. An increase in LA results in a decrease in UFV. Endogenous hormones may modulate peritoneal membrane permeability and LA. This study was conducted to assess the effect of angiotensin II(AII) on peritoneal permeability and LA in rat. Rats (BW, approximately 300g) with normal renal function were dialyzed for 4 hours using 30ml of hypertonic dialysate (dextrose concentration: 3.86%). AII was added in dialysate at the concentration of 10(-9)-10(-2) mol/30ml. Peritoneal membrane permeability and UFV were studied by clearance of urea N and inorganic phosphate, albumin excretion, glucose absorption and LA. LA was calculated by the concentration change of dextran 70 in dialysate. AII decreased UFV from 15.7 +/- 2.8ml/4hr(control) to 5.7 +/- 1.5(AII 10(-4) mol/dwell). LA was increased in a dose dependent fashion (ED50:0.25 x 10(-6)mol) with no change in TCUF and clearances of urea N and inorganic phosphate. Ten types of AII analogue were used to investigate the site of action for LA in 8 amino acids of AII. [beta-Asp1], [Val5], [Ile3, Val5] and [Sar1] AII showed agonistic action against LA. [Sar1, Thr8], [Sar1, Ile8], [Sar1, Leu8], [Sar1, Ala8], [Sar1, Val5, Ala8] and [Sar1, Gly8] AII had no effect on LA, which found the importance of the 8th amino acid of AII for LA. These actions of AII analogue against LA were similar to those for vascular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Hydrogen bond network of cytochrome P-450cam: a network connecting the heme group with helix K

During investigations of the structural character of a mutant P-450cam where Glu-286 is replaced with lysine, we obtained evidence of a hydrogen bond network between helix K and the heme group via helix L of P-450cam. This mutant protein loses the ability to maintain the heme group in a proper position, possibly due to a break in the hydrogen bond network.

[A case of middle lobar bulla associated with severe bronchial asthma]

We experienced a case of middle lobar bulla associated with severe bronchial asthma. Bulla occurs favoritely at apical area and S6, and middle lobar bulla which is very rare has been reported to cause higher ventilatory disorder compared with superior lobar bulla, when it becomes giant. The pathogenesis of the present middle lobar bulla remains unknown, but steroid administration to bronchial asthma may possibly have influenced pleura and/or lung parenchyma. We would like to make its further observation, paying attention to its possible recurrence and its occurrence at other sites.

Quantitative and qualitative changes of serum albumin in CAPD patients

This study was conducted to assess quantitative and qualitative changes in serum albumin in CAPD patients. For twenty-six CAPD patients as well as age-, sex- and dialysis history-matched HD patients, biochemical and physiological parameters including urea kinetics were determined. Albumin was qualitatively evaluated by HPLC. The CAPD patients showed significant decreases in serum albumin and the reduced form of albumin accompanied by a lower protein catabolic rate(PCR) compared to the HD patients. Thirty five % of CAPD patients showed mild to moderate hypoalbuminemia, associated with a higher incidence of peritonitis and longer hospital stay. Patients with hypoalbuminemia had less of the reduced form of albumin. A weak positive correlation was found between serum albumin concentration and KT/V, and PCR. Thus, in CAPD patients, there occur quantitative and qualitative changes in serum albumin. Hypoalbuminemia may be a risk factor for peritonitis and is due in part to insufficient dialysis and protein intake. Intermolecular change in albumin may possibly be due to uremia per se.

Diversity of a ribonucleoprotein family in tobacco chloroplasts: two new chloroplast ribonucleoproteins and a phylogenetic tree of ten chloroplast RNA-binding domains

Two new ribonucleoproteins (RNPs) have been identified from a tobacco chloroplast lysate. These two proteins (cp29A and cp29B) are nuclear-encoded and have a less affinity to single-stranded DNA as compared with three other chloroplast RNPs (cp28, cp31 and cp33) previously isolated. DNA sequencing revealed that both contain two consensus sequence-type homologous RNA-binding domains (CS-RBDs) and a very acidic amino-terminal domain but shorter than that of cp28, cp31 and cp33. Comparison of cp29A and cp29B showed a 19 amino acid insertion in the region separating the two CS-RBDs in cp29B. This insertion results in three tandem repeats of a glycine-rich sequence of 10 amino acids, which is a novel feature in RNPs. The two proteins are encoded by different single nuclear genes and no alternatively spliced transcripts could be identified. We constructed a phylogenetic tree for the ten chloroplast CS-RBDs. These results suggest that there is a sizable RNP family in chloroplasts and the diversity was mainly generated through a series of gene duplications rather than through alternative pre-mRNA splicing. The gene for cp29B contains three introns. The first and second introns interrupt the first CS-RBD and the third intron does the second CS-RBD. The position of the first intron site is the same as that in the human hnRNP A1 protein gene.

Recurrent perforations of viscus due to ventriculoperitoneal shunt in a hydrocephalic child

In this report, we describe the first case of recurrent perforations of viscus due to ventriculoperitoneal shunt for the treatment of hydrocephalus. Based on our own experience and a survey of literature, we suggest that perforation of the gastrointestinal tract should be suspected in patients with ventriculoperitoneal shunt, particularly when abdominal symptoms or ventriculitis are presented. To manage this complication, at the first perforation in the present case, a fibrin sealant was effective for closure of the perforated stomach wall. At the second perforation, when laparotomy was performed, we could not find any abnormality in the abdominal cavity except for a sheath and slight omental adhesions near it.

RNase-like domain in DNA-directed RNA polymerase II

DNA-directed RNA polymerase is responsible for gene expression. Despite its importance, many details of its function and higher-order structure still remain unknown. We report here a local sequence similarity between the second largest subunit of RNA polymerase II and bacterial RNases Ba (barnase), Bi, and St. The most remarkable similarity is that the catalytic sites of the RNases are shared with the eukaryotic RNA polymerase II subunits of Drosophila melanogaster and Saccharomyces cerevisiae. Several amino acids conserved among the RNases and the RNase-like domains of the RNA polymerase subunits are located in the neighborhood of the catalytic sites of barnase, whose three-dimensional structure has been resolved. This observation suggests the functional importance of the RNase-like domain of the RNA polymerase subunits and indicates that the RNase-like domain may have RNase activity. The location of the RNase-like domain relative to the region necessary for RNA polymerization is similar to the relative proximity of 5'----3' or 3'----5' exonuclease and the region of polymerase activity of DNA polymerase I. The RNase-like domain might work in proofreading, as in RNA-directed RNA polymerase of influenza virus, or it may contribute to RNA binding through an unknown function.

Molecular cloning of the human gene, CCG2, that complements the BHK-derived temperature-sensitive cell cycle mutant tsBN63: identity of CCG2 with the human X chromosomal SCAR/RPS4X gene

A temperature-sensitive mutant tsBN63 cell line was isolated by the fluorodeoxyuridine method from the BHK21/13 cell line after mutagenesis with nitrosoguanidine. When cultures of tsBN63 cells growing asynchronously at 33.5 degrees C were shifted to 39.5 degrees C, a nonpermissive temperature, the ability for protein synthesis was rapidly reduced and cell proliferation stopped mainly at G1 phase, and partly at G2 phase. Synchronized cultures of tsBN63 cells did not commence DNA synthesis when shifted up in G1 phase. The human gene complementing the tsBN63 mutation was cloned by DNA-mediated gene transfer and its cDNA of 1.1 kb conferring ts+ phenotype on tsBN63 cells was isolated from the cDNA library of Raj (mer+) cells with a frequency of 10(−3). On the basis of the determined nucleotide sequence, the isolated human gene turned out to be the X chromosomal RPS4X encoding the ribosomal protein S4. The size of the CCG2 gene was estimated to be about 12 kb by complementation analysis of the tsBN63 mutation with cloned genomic DNA.

[A case of retrovesical embryonal cell carcinoma]

We report a case of an extragonadal germ cell tumor in the retrovesical region. The patient complained of a perineal and micturition pain. Urethrography, CT and MRI showed a retrovesical tumor protruding into the bladder. Alfa-fetoprotein was increased to 12,170 ng/ml. Bilateral testes did not contain any palpable mass by careful palpation. No tumor was detected by ultrasonography, either. Clinically, he was diagnosed as having a retrovesical extragonadal germ cell tumor associated with paraaortic lymph-nodes and bilateral pulmonary metastases. Although he was treated by combination chemotherapy (PVB and VAB-6 regimen) and irradiation, he died of carcinomatosis about 6 months after the admission. There was no evidence of tumor in bilateral testes on autopsy. This case was a second case of extragonadal germ cell tumor originating from the retrovesical lesion in the literature.

Evolutionary origin of thyroglobulin by duplication of esterase gene

Rat liver microsomal carboxyesterase E1 was found to have homology with five esterases and with the COOH-terminal parts of two thyroglobulins. A phylogenetic tree constructed for these proteins shows that this new superfamily has evolved from a common ancestral gene that encoded a carboxyesterase. The tree also shows that the ancestral gene already existed before the divergence of vertebrates and invertebrates and later its duplicated genes gained various kinds of esterase activity. According to the tree, one of the duplicated genes evolved into the COOH-terminal half of thyroglobulin by a gene fusion with a DNA sequence whose evolutionary origin is unknown.

Molecular cloning and nucleotide sequence of cDNA of microsomal carboxyesterase E1 of rat liver

cDNA clones of the mRNA for rat liver carboxyesterase E1, one of the carboxyesterases exclusively located on the luminal side of microsomal vesicles, were isolated. Sequence analysis of 2 kbp long cDNA revealed the primary structure of carboxyesterase E1, which consisted of 549 amino acids (Mr 60, 171.71) and contained an extra peptide of 18 amino acids at the NH2-terminus of the mature enzyme. Comparison of the deduced primary structure and sequences of some proteolytic fragments of the purified enzyme indicated the multiplicity of the enzyme. The extra peptide at the NH2-terminal had features in common with the signal peptides of most secretory proteins. However, no polar amino acid residues existed before the hydrophobic core of the signal peptide. A new interpretation is proposed to explain how the signal peptide without the NH2-terminal polar residues works. A tetrapeptide (KDEL) which was shown to keep a few microsomal proteins in the lumen of the endoplasmic reticulum was not found in the primary structure of carboxyesterase E1, which suggested the existence of another mechanism for retention of proteins in the lumen of endoplasmic reticulum. Carboxyesterase E1 showed significant homology with the COOH-terminal portion of thyroglobulin.

Peptide histidine methionine may be a prolactin-releasing hormone in humans

Peptide histidine isoleucine (PHI) was initially isolated from the porcine gastrointestinal tract and may be present in the brain. It has been suggested that PHI may be PRL-releasing hormone (PRH) because of its potent PRL-releasing activity and its existence in hypophysial portal plasma in rats. Vasoactive intestinal peptide and PHI are coded by the same gene, and human PHI has a C-terminal methionine instead of isoleucine [peptide histidine methionine (PHM)]. To investigate the possibility that PHM is a physiological PRH in humans, we measured the immunoreactive PHM concentration in human hypothalamic tissue and cerebrospinal fluid (CSF) using a specific RIA. We also examined in vivo the PRH activity of synthetic PHM. The human hypothalamus contained 19.3 +/- 6.2 (+/- SD; n = 5) pmol/hypothalamus, very similar to the content of GHRH or CRH. Immunoreactive PHM was also present in CSF; its levels in CSF were significantly lower in patients with prolactinomas than in control subjects. The CSF PHM levels in such patients increased after correction of hyperprolactinemia by long term bromocriptine therapy. The CSF PHM levels also were low in pregnant women. There was a significant negative correlation between plasma PRL and CSF PHM levels in all of these subjects. Gel filtration profiles of CSF extracts from normal subjects revealed two peaks of immunoreactive PHM: a high mol wt peak and one at the elution position of synthetic PHM. This profile resembled that of hyppothalamic extract. In contrast, only high mol wt material was detected in CSF from hyperprolactinemic subjects. Intravenous administration of synthetic PHM elicited a significant increase in plasma PRL in normal subjects; the responses to PHM were higher in women than in men. The presence of large amounts of immunoreactive PHM in the human hypothalamus suggests that PHM may participate in the regulation of anterior pituitary hormone secretion. Its specific PRL-releasing activity in vivo and the low CSF PHM levels of hyperprolactinemic subjects suggest that PHM may be a physiological PRH in humans.

Phorbol ester modulates serotonin-stimulated phosphoinositide breakdown in cultured vascular smooth muscle cells

Stimulation of cultured rabbit aortic vascular smooth muscle cells (VSMC) with serotonin (5HT) induced a rapid generation of inositol phosphates from receptor-mediated hydrolysis of inositol phospholipids. Pretreatment of these cells with 500ng/ml of pertussis toxin for 24h prior to addition of 5HT reduced 5HT-induced formation of inositol phosphates. Phorbol esters, such as 12-O-tetradecanoylphorbol-13-acetate (TPA) or phorbol-12,13-dibutyrate (PDBu), are known to activate protein kinase C (PKC), but their role on cultured VSMC stimulated by 5HT has not been defined. TPA exhibited a rapid inhibition of 5HT-stimulated phosphoinositide breakdown, although 4 alpha-phorbol-12,13-didecanoate (4 alpha PDD), an inactive phorbol ester, did not inhibit it. These data suggest that a guanine nucleotide inhibitory (Gi) protein couples 5HT receptor to phospholipase C and TPA modulates 5HT-stimulated hydrolysis of inositol phospholipids in cultured VSMC through activation of PKC.

[Correlation between histological grading and the prognosis of prostatic carcinoma--a comparative study of the Japanese General Rules of Prostatic Cancer (JGRPC) and Gleason's classification]

One hundred and sixty-seven patients with newly diagnosed, previously untreated prostatic adenocarcinoma, during the period between July, 1971 and March, 1934, were studied. The histopathologic specimens of the prostate were classified by the Japanese General Rules of Prostatic Cancer (JGRPC) and by Gleason's classification. The number of patients with well, moderately and poorly differentiated prostatic carcinomas according to the JGRPC classification was 42, 74 and 51 respectively, and the number of the patients with Gleason's pattern 1, 2, 3, 4, and 5 was 24, 20, 32, 43 and 48, respectively. The number of patients with Gleason's score (primary plus secondary pattern) 2 to 4, 5 to 7 and 8 to 10 groups was 40, 76 and 51 respectively. There was no significant difference in survival rate between well and moderately differentiated groups, but the survival rate of the group with poorly differentiated tumor was significantly lower than that of the moderately differentiated (p less than 0.01) and well differentiated (p less than 0.001) groups. There was no significant difference in 10-year survival rate between the score 2-4 and score 5-8 groups, but the score 9-10 group had a significantly lower survival rate than the score 5-8 group (p less than 0.01) and score 2-4 (p less than 0.005) group. JGRPC and Gleason's classification are thought to be equally useful in estimating prognosis of prostatic cancer, but the former is more concise and easily applicable than the latter.