Ethanol Metabolism Dynamics in Clostridium ljungdahlii Grown on Carbon Monoxide.

Bioethanol production from syngas using acetogenic bacteria has attracted considerable attention in recent years. However, low ethanol yield is the biggest challenge that prevents the commercialization of syngas fermentation into biofuels using microbial catalysts. The present study demonstrated that ethanol metabolism plays an important role in recycling NADH/NAD+ during autotrophic growth. Deletion of bifunctional aldehyde/alcohol dehydrogenase (adhE) genes leads to significant growth deficiencies in gas fermentation. Using specific fermentation technology in which the gas pressure and pH were constantly controlled at 0.1 MPa and 6.0, respectively, we revealed that ethanol was formed during the exponential phase, closely accompanied by biomass production. Then, ethanol was oxidized to acetate via the aldehyde ferredoxin oxidoreductase pathway in Clostridium ljungdahlii A metabolic experiment using 13C-labeled ethanol and acetate, redox balance analysis, and comparative transcriptomic analysis demonstrated that ethanol production and reuse shared the metabolic pathway but occurred at different growth phases.IMPORTANCE Ethanol production from carbon monoxide (CO) as a carbon and energy source by Clostridium ljungdahlii and "Clostridium autoethanogenum" is currently being commercialized. During gas fermentation, ethanol synthesis is NADH-dependent. However, ethanol oxidation and its regulatory mechanism remain incompletely understood. Energy metabolism analysis demonstrated that reduced ferredoxin is the sole source of NADH formation by the Rnf-ATPase system, which provides ATP for cell growth during CO fermentation. Therefore, ethanol production is tightly linked to biomass production (ATP production). Clarification of the mechanism of ethanol oxidation and biosynthesis can provide an important reference for generating high-ethanol-yield strains of C. ljungdahlii in the future.

[Effect of STIL on the Gene Expression Profile of Gastric Cancer Cells].

Objective To explore the molecular mechanism underlying gastric carcinogenesis and progression by using gene expression profiling array together with bioinformatics. Methods Lentivirus short hairpin RNA targeting STIL(ShSTIL)and scrambled sequence RNA(ShCon)were transduced into the gastric cancer cell line SGC-7901.RNA extraction,complementary DNA synthesis,construction of biotin-labelled amplified RNA probes,and hybridization with gene expression profile were consecutively performed.We collected corresponding data and analyzed differentially expressing genes(DEGs),followed by the analysis of gene ontology(GO)and Kyoto encyclopedia of genes and genomes(KEGG)enrichment,transcription factor regulating network,and protein-protein interacting networks. Results Compared with ShCon,a total of 417 and 87 genes were respectively down-regulated and up-regulated,respectively,in the ShSTIL group(P<0.05,fold change>1 or <-1).GO and KEGG enrichment analysis indicated that genes regulated by STIL were localized in cytoplasm,extracellular exosome,Golgi apparatus and various biomembranes,and were implicated in the ubiquitin-mediated proteolysis,P53 signaling pathway,and pathways regulating pluripotency of stem cells.Evaluation on genes enriched in KEGG pathways,regulation of transcription factors,and protein-protein interacting network demonstrated that IGF1R,STUB1,SKP2,and FOXO1 were localized at the centre of the network and played a key role in the development and progression of gastric cancer. Conclusion Through the protein-protein interactions,STIL may activate E3 ubiquitin ligase STUB1 or SKP2,promote the proteolysis of FOXO1-a transcription factor,regulate the expression of IGF1R,and thus promote gastric carcinogenesis and progression.

Direct Involvement of the Master Nitrogen Metabolism Regulator GlnR in Antibiotic Biosynthesis in Streptomyces.

GlnR, an OmpR-like orphan two-component system response regulator, is a master regulator of nitrogen metabolism in the genus Streptomyces In this work, evidence that GlnR is also directly involved in the regulation of antibiotic biosynthesis is provided. In the model strain Streptomyces coelicolor M145, an in-frame deletion of glnR resulted in markedly increased actinorhodin (ACT) production but reduced undecylprodigiosin (RED) biosynthesis when exposed to R2YE culture medium. Transcriptional analysis coupled with DNA binding studies revealed that GlnR represses ACT but activates RED production directly via the pathway-specific activator genes actII-ORF4 and redZ, respectively. The precise GlnR-binding sites upstream of these two target genes were defined. In addition, the direct involvement of GlnR in antibiotic biosynthesis was further identified in Streptomyces avermitilis, which produces the important anthelmintic agent avermectin. We found that S. avermitilis GlnR (GlnRsav) could stimulate avermectin but repress oligomycin production directly through the respective pathway-specific activator genes, aveR and olmRI/RII To the best of our knowledge, this report describes the first experimental evidence demonstrating that GlnR regulates antibiotic biosynthesis directly through pathway-specific regulators in Streptomyces Our results suggest that GlnR-mediated regulation of antibiotic biosynthesis is likely to be universal in streptomycetes. These findings also indicate that GlnR is not only a master nitrogen regulator but also an important controller of secondary metabolism, which may help to balance nitrogen metabolism and antibiotic biosynthesis in streptomycetes.

Incidence and prognosis of olfactory and gustatory dysfunctions related to SARS-CoV-2 Omicron strain infection in China: A national multicenter survey of 35,566 individuals.

Objective: This cross-sectional study aimed to determine the epidemiology of olfactory and gustatory dysfunctions related to COVID-19 in China. Methods: This study was conducted by 45 tertiary Grade-A hospitals in China. Online and offline questionnaire data were obtained from patients infected with COVID-19 between December 28, 2022, and February 21, 2023. The collected information included basic demographics, medical history, smoking and drinking history, vaccination history, changes in olfactory and gustatory functions before and after infection, and other postinfection symptoms, as well as the duration and improvement status of olfactory and gustatory disorders. Results: Complete questionnaires were obtained from 35,566 subjects. The overall incidence of olfactory and taste dysfunction was 67.75%. Being female or being a cigarette smoker increased the likelihood of developing olfactory and taste dysfunction. Having received four doses of the vaccine or having good oral health or being a alcohol drinker decreased the risk of such dysfunction. Before infection, the average olfactory and taste VAS scores were 8.41 and 8.51, respectively; after infection, they decreased to 3.69 and 4.29 and recovered to 5.83 and 6.55 by the time of the survey. The median duration of dysosmia and dysgeusia was 15 and 12 days, respectively, with 0.5% of patients having symptoms lasting for more than 28 days. The overall self-reported improvement rate was 59.16%. Recovery was higher in males, never smokers, those who received two or three vaccine doses, and those that had never experienced dental health issues, or chronic accompanying symptoms. Conclusions: The incidence of dysosmia and dysgeusia following infection with the SARS-CoV-2 virus is high in China. Incidence and prognosis are influenced by several factors, including sex, SARS-CoV-2 vaccination, history of head-facial trauma, nasal and oral health status, smoking and drinking history, and the persistence of accompanying symptoms.

Three of four GlnR binding sites are essential for GlnR-mediated activation of transcription of the Amycolatopsis mediterranei nas operon.

In Amycolatopsis mediterranei U32, genes responsible for nitrate assimilation formed one operon, nasACKBDEF, whose transcription is induced by the addition of nitrate. Here, we characterized GlnR as a direct transcriptional activator for the nas operon. The GlnR-protected DNA sequences in the promoter region of the nas operon were characterized by DNase I footprinting assay, the previously deduced Streptomyces coelicolor double 22-bp GlnR binding consensus sequences comprising a1, b1, a2, and b2 sites were identified, and the sites were then mutated individually to test their roles in both the binding of GlnR in vitro and the GlnR-mediated transcriptional activation in vivo. The results clearly showed that only three GlnR binding sites (a1, b1, and b2 sites) were required by GlnR for its specific binding to the nas promoter region and efficient activation of the transcription of the nas operon in U32, while the a2 site seemed unnecessary.

[Effect of renal sympathetic denervation on left ventricular hypertrophy and inflammatory factors in spontaneously hypertensive rats].

OBJECTIVE: To investigate the effect of renal sympathetic denervation on left ventricular hypertrophy and inflammatory factors in spontaneously hypertensive rats. METHODS: Thirty six spontaneously hypertensive rats (SHR) were divided into 3 groups with 12 animals in each group: SHR control group,operation group and sham operation group. Bilateral renal sympathectomy or sham operation were performed in operation and sham groups,respectively; another 12 WKY rats served as normal controls. The blood pressure and body weight were examined weekly. The animals were sacrificed at w1 and w6, rat hearts were collected and left ventricular mass index (LVMI) was calculated. The expression of TLR4,TNF-α and IL-6 in heart tissue were detected by immunohistochemistry and Western blot. RESULTS: The systolic blood pressure [(201.67 ± 11.09) mmHg compared with (140.0 ± 10.86)mmHg,P<0.05],diastolic blood pressure [(144.50 ± 10.48)mmHg compared with (78.50 ± 7.32)mmHg,P<0.05], LVMI (2.44 ± 0.05 compared with 1.93 ± 0.05,P<0.05),the expression of TLR4 (0.298 ± 0.004 compared with 0.126 ± 0.004, P<0.05), NF-κB (0.249 ± 0.006 compared with 0.195 ± 0.005, P<0.05),TNF-α(0.323 ± 0.004 compared with 0.146 ± 0.004,P <0.05), IL-6 (0.283 ± 0.005 compared with 0.207 ± 0.006, P<0.05) in SHR control group were significantly higher than those in WKY group. Compared to sham operation group,the systolic blood pressure (157.30 ± 9.35 compared with 197.30 ± 11.5, P<0.05),diastolic blood pressure (112.50 ± 6.25 compared with 146.80 ± 7.6, P<0.05),LVMI (2.32 ± 0.04 compared with 2.57 ± 0.09, P<0.05, TLR4 (0.198 ± 0.006 compared with 0.317 ± 0.008, P<0.05), NF-κB (0.208 ± 0.006 compared with 0.332 ± 0.007, P<0.05), TNF-α(0.27 ± 0.009 compared with 0.375 ± 0.004,P<0.05), IL-6 (0.218 ± 0.004 compared with 0.376 ± 0.009, P<0.05) in operation group were all decreased at w1 after sympathectomy. Six weeks after the operation,there were no significant differences in systolic blood pressure (197.50 ± 12.13 compared with 208.83 ± 10.23,P>0.05) and diastolic blood pressure (150.33 ± 7.74 compared with 151.50 ± 8.22, P>0.05) between denervated and sham-operated SHRs; however,the LVMI (2.46 ± 0.07 compared with 2.81 ± 0.05,P<0.05) and the expression of TLR4(0.301 ± 0.009 compared with 0.567 ± 0.006, P<0.05), NF-κB (0.251 ± 0.004 compared with 0.476 ± 0.009,P<0.05),TNF-α(0.324 ± 0.005 compared with 0.535 ± 0.006, P<0.05,IL-6 (0.285 ± 0.009 compared with 0.549 ± 0.007, P<0.05) in operation group were still significantly lower than those in sham operation group. CONCLUSION: Renal sympathetic denervation can significantly delay the progression of LVH in SHR, which may associated with lowering blood pressure and decreasing expression of TLR4, NF-κB,TNF-α, IL-6 in myocardial tissue.

Endoscopic surgery of cavernous sinus tumors originating from the extradura.

In the present study, we explored the effects of various endoscopic approaches in patients with cavernous sinus (CS) tumors. Five endoscopic approaches, including the endoscopic transseptal transsphenoidal approach, extended endoscopic transseptal transsphenoidal approach, extended transnasal transmaxillary approach, extranasal extended maxillary sinus approach, and endoscopic transnasal transpterygoid approach, were selected for the resection of CS tumors from 36 patients. Thirty gross total tumors and 6 subtotal tumors were removed. After a follow-up period of 6 months to 3 years, 30 patients were determined to be recurrence-free, and 2 patients had unchanged residual tumors. One patient with a recurrent pituitary adenoma underwent a second surgery, and 1 patient with chordoma died because of an intracavernous carotid artery rupture 18 months after the operation. Various endoscopic approaches tailored to the origin and extent of the CS tumor were proven efficacious for the maximal and precise removal of CS tumors while avoiding vital structures.

N6-Methyladenosine RNA Modification Landscape in the Occurrence and Recurrence of Nasopharyngeal Carcinoma.

Background: Nasopharyngeal carcinoma (NPC) is a type of squamous head and neck cancer with variable geographic distributions, with the highest incidence in Southeast Asia. Its primary treatment is radiotherapy due to its high radio sensitivity. However, the N6-methyladenosine (m6A) landscape in NPC, including recurrent NPC, has not been reported. Methods: In this study, m6A RNA immunoprecipitation (RIP) sequencing and microarray sequencing were performed on 12 tissue samples tissues of patients with primary and recurrent NPC. The expression profiles of m6A-related and non-coding RNAs were constructed and explored. Then, function experiments were performed to evaluate the effects of methyltransferase (METTL)3, METTL14 and WT1 associated protein (WTAP) on progressions of NPC. Finally, immunohistochemistry (IHC) and survival analysis were performed to confirm the correlation between METTL3, METTL14 and WTAP and NPC patients' clinical outcomes. Results: This study mapped m6A RNA modification and RNA expression profiles in normal nasopharynx, primary NPC, and recurrent NPC tissues. This study also explored the role of m6A modificators in NPC development and recurrence. METTL3, METTL14, and WTAP could promote invasion and metastasis of NPC, and that these three proteins could induce radiotherapy resistance in NPC cells through DNA repair. Moreover, we found that METTL3, METTL14, and WTAP promoted an increase in exosomes within NPC microenvironment. Conclusions: This study suggests that the alteration of m6A modification in primary and recurrent NPCs may play an important role in the development and progression of NPC.

Resection of extensive sellar tumors with extended endoscopic transseptal transsphenoidal approach.

The endoscope has recently been used to extensive sellar lesions, but the extended areas of the lesions and operative techniques vary from each study. Here we present our experience with extended endoscopic transseptal transsphenoidal (EETT) approach to 16 patients with extensive sellar lesion and evaluate the feasibility of EETT in different extensive sellar tumor resection. Sixteen patients with extensive sellar lesion were operated by EETT approach in this study. The approach included unilateral posterior septum mucosa resection, posterior septectomy, extended ethmoidectomy and sphenoidoctomy, four tumoral circumferences (bilateral, superior, inferior aspects) isolated and subsequently tumoral removal from outside to inside of the tumors obtained. This surgical procedure is satisfactory for sellar lesion with different juxtasellar extension. After surgery, CT scan and MR image showed that total removal of the tumor was achieved in 10 patients. Six patients who received subtotal resection were treated with postoperative radiation therapy or gamma knife surgery. Two patients developed postoperative cerebrospinal fluid leak that was successfully managed by conservative treatment within 6 days after surgery. No other new postoperative endocrinological or neurological defects occurred. Six months to 5 years follow up indicated that all 16 patients with the visual disturbances and 4 patients with endocrine impairments have recovered or improved. One patient with malignant meningioma died due to recurrence of the tumor 2 years postoperation. Another one patient with malignant inverted papilloma recurred 1 year postoperation and underwent operation and radiation therapy again. The EETT approach might better facilitate the removal of different extensive sellar lesions with maximal preservation of important anatomical structures and nasal function.

[A preliminary study of endoscopic transoral trans-posteriorwall pharynx resection of hypo-clivus chordoma].

OBJECTIVE: To introduce a endoscopic surgical approach for hypo-clivus chordoma, and to explore the clinical value of the endoscopic resection of hypo-clivus chordoma. METHODS: Three hypo-clivus chordoma were resected by endoscopic transoral tans-posteriorwall pharynx approach. RESULTS: The MR image showed that total removal of the tumor was achieved in 2 patients and subtotal resection was received in one patient. No severe postoperative complications and sequelae occurred. In 6 months to 2 years' follow-up, the MRI showed that 2 patients had no residue tumor, and one patient died due to recurrence of the tumor 1 year after operation. CONCLUSION: The endoscopic transoral tans-posteriorwall pharynx approach might be valuable in the treatment of the hypo-clivus chordoma. The use of the endoscope allows for direct access to the hypo-clivus lesions while minimizing the chances of surrounding anatomic structure injury. In addition, this approach has the advantages of quick recovery, avoidance of catastrophic complications and sequelae. Especially, various angle view of the endoscope provides a panoramic view of the hypo-clivus, thus exposing and resecting hide lesion which can not be exposed by other approaches. This approach might facilitate complete resection of the chordoma with maximal preservation of normal tissues.

[Myeloperoxidase in the plasma of patients with acute coronary syndrome].

OBJECTIVE: To determine the diagnostic value and efficacy for risk stratification of myeloperoxidase (MPO) levels in patients with acute coronary syndrome (ACS). METHODS: One hundred and sixty-two patients were enrolled in this study. All patients underwent coronary angiography. They were divided into 3 groups: ACS group (n=54), SAP group (n=54) and control group (n=54). Blood samples were taken from the artery before angiography in all patients and the concentrations of MPO, hsCRP and cTnI were measured. Each subject was asked details of history of hypertension, hyperlipidemia, diabetes and smoking habits. The efficacy of therapy, the cardiovascular events (myocardial infarction, the need for revascularization, or death) were recorded after 6 months of follow-up. RESULTS: The plasma MPO level in ACS group (30.98 ng/mL) was significantly higher than those in the SAP group (14.67 ng/mL) and the control group(14.23 ng/mL)(P<0.01), and the plasma MPO levels in patients of the SAP group and the control group were not significantly different (P=0.74). There was no obvious correlation between the levels of plasma MPO and the serum levels of cTnI, hsCRP,the prevalence of the 4 major risk factors for CHD. Multivariate logistic regression analysis showed that plasma MPO level, free plasma glucose and sex were the significant variables. The risk for subsequent cardiovascular events was higher in the patients with elevated level of MPO. CONCLUSION: Plasma MPO may be a new risk biomarker for ACS and may predict the incidence of subsequent cardiovascular events.

Androgen actions on endothelium functions and cardiovascular diseases.

The roles of androgens on cardiovascular physiology and pathophysiology are controversial as both beneficial and detrimental effects have been reported. Although the reasons for this discrepancy are unclear, multiple factors such as genetic and epigenetic variation, sex-specificity, hormone interactions, drug preparation and route of administration may contribute. Recently, growing evidence suggests that androgens exhibit beneficial effects on cardiovascular function though the mechanism remains to be elucidated. Endothelial cells (ECs) which line the interior surface of blood vessels are distributed throughout the circulatory system, and play a crucial role in cardiovascular function. Endothelial progenitor cells (EPCs) are considered an indispensable element for the reconstitution and maintenance of an intact endothelial layer. Endothelial dysfunction is regarded as an initiating step in development of atherosclerosis and cardiovascular diseases. The modulation of endothelial functions by androgens through either genomic or nongenomic signal pathways is one possible mechanism by which androgens act on the cardiovascular system. Obtaining insight into the mechanisms by which androgens affect EC and EPC functions will allow us to determine whether androgens possess beneficial effects on the cardiovascular system. This in turn may be critical in the prevention and therapy of cardiovascular diseases. This article seeks to review recent progress in androgen regulation of endothelial function, the sex-specificity of androgen actions, and its clinical applications in the cardiovascular system.

Synthetic peptides derived from SARS coronavirus S protein with diagnostic and therapeutic potential.

The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) is an important viral structural protein. Based on bioinformatics analysis, 10 antigenic peptides derived from the S protein sequence were selected and synthesized. The antigenicity and immunoreactivity of all the peptides were tested in vivo and in vitro. Four peptides (P6, P8, P9 and P10) which contain B cell epitopes of the S protein were identified, and P8 peptide was confirmed in vivo to have a potential in serological diagnosis. By using a syncytia formation model, we tested the neutralization ability of all 10 peptides and their corresponding antibodies. It is interesting to find that P8 and P9 peptides inhibited syncytia formation, suggesting that the P8 and P9 spanning regions may provide a good target for anti-SARS-CoV drug design. Our data suggest that we have identified peptides derived from the S protein of SARS-CoV, which are useful for SARS treatment and diagnosis.

The spike protein of severe acute respiratory syndrome (SARS) is cleaved in virus infected Vero-E6 cells.

Spike protein is one of the major structural proteins of severe acute respiratory syndrome-coronavirus. It is essential for the interaction of the virons with host cell receptors and subsequent fusion of the viral envelop with host cell membrane to allow infection. Some spike proteins of coronavirus, such as MHV, HCoV-OC43, AIBV and BcoV, are proteolytically cleaved into two subunits, S1 and S2. In contrast, TGV, FIPV and HCoV-229E are not. Many studies have shown that the cleavage of spike protein seriously affects its function. In order to investigate the maturation and proteolytic processing of the S protein of SARS CoV, we generated S1 and S2 subunit specific antibodies (Abs) as well as N, E and 3CL protein-specific Abs. Our results showed that the antibodies could efficiently and specifically bind to their corresponding proteins from E.coli expressed or lysate of SARS-CoV infected Vero-E6 cells by Western blot analysis. Furthermore, the anti-S1 and S2 Abs were proved to be capable of binding to SARS CoV under electron microscope observation. When S2 Ab was used to perform immune precipitation with lysate of SARS-CoV infected cells, a cleaved S2 fragment was detected with S2-specific mAb by Western blot analysis. The data demonstrated that the cleavage of S protein was observed in the lysate, indicating that proteolytic processing of S protein is present in host cells.

[Sequence and functional analysis of the chromosome replication origin (oriC) of Streptoverticillum caespitosus ATCC27422].

Twenty-two DnaA boxes were identified in the chromosome replication origin (oriC) of Streptoverticillum caespitosus ATCC27422 based upon the characteristics of consensus sequences. The 21st and 22nd DnaA boxes overlapped 8 base pairs each other reversely. Compared with the oriC database of actinomycetes, similar overlapping DnaA boxes were recognized in several species of Streptomyces and Mycobacterium. These overlapping DnaA boxes were composed of the last two DnaA box (21st and 22nd) in the Streptomyces species, but the of 1st and 2nd ones in the Mycobacterium species. The consensus sequence of the overlapping DnaA box is CTGTGCACAA, one base longer than the normal DnaA box sequence presumably due to the overlapping structure. Although the DnaA boxes exist in the 189 792 bp region only, the 1 188 bp and 793 939 bp regions are also important to the DNA replication. Deletion of the 1 188 bp region may cause absolute loss of DNA replication initiation activity measured by the transformation efficiency of plasmids with truncated oriC. When the 793 939 bp region was truncated, the transformation efficiency reduced about 40%. If the oriC was cloned into a vector with partial flanking region sequences (partial dnaA and dnaN gene sequences), the transformation rate was about 4.3-fold lower than that of the construct containing the oriC region only. However, the transformants were much more similar to the host with respect to the morphology of colony and mycelium. The cis-regulatory functions of the flanking sequences, which may influence the initiation efficiency of the chromosome replication and/or the stability of replicon, are thus suggested.

Site-directed Mutagenesis of the Active Center of Penicillin Acylase from E. coli ATCC 11105.

Site-directed mutagenesis and chemical modification were performed at Ser290 of the penicillin G acylase from E. coli ATCC11105. The Ser290 was substituted by Cys or Secys. Wild type and mutant proteins were purified, and the activities and kinetic constants of penicillin acylases for hydrolysis and synthesis were determined, respectively. Although their K(m) values were not changed, the k(cat) values of the thiol-PGA and seleno-PGA were decreased from 135s(-1) to 0.63s(-1) and 0.38s(-1) against NIPAB, and from 34.38s(-1) to 0.23s(-1) and 0.06s(-1) against penicillin G. Contrary to Choi's report(Choi K S (et al. J Bacteriology), 1992, 10 6270-6276), we found that hydrolysis activity was certainly kept in the mutant of penicillin acylase. In addition, the specific activities of synthesis were decreased by 5-fold and 20-fold, respectively.

[Isolation and characterization of functional replication origin from Streptomyces avermitilis].

Most eubacteria contain highly conservative gene clusters in the adjacent regions of oriC. According to this principle, a 1.4 kb DNA fragment containing parts of dnaA and dnaN genes of Streptomyces avermitilis was cloned by degenerate PCR. Sequence analysis of this fragment indicated that it encoded two partial genes in the order dnaA (the putative initiator protein) and dnaN (the beta subunit of DNA polymerase III). The intergenic non-coding region between dnaA and dnaN was found to contain 19 putative DnaA boxes, i.e. 9 nt long DnaA protein recognition sequences. It was confirmed that the location, orientation and spacing of DnaA boxes in this intergenic region are conserved among Streptomyces. The consensus sequence of DnaA box identified is (T/C)(T/C)(G/A/C)TCCACA (preferred bases in italic). When this fragment was cloned into Escherichia coli plasmid pQC156, which is otherwise non-replicative in Streptomyces, it exhibited autonomous replication activity in Streptomyces lividans, a closely related Streptomyces strain. Different parts of the oriC contribute unequally to the stability and transformation efficiency. The 3' region of oriC may contain features that support stable autonomous replication. The implications of these results for the understanding of the S. avermitilis oriC replication initiation process and its future application are discussed.

Expression of gene encoding GL-7ACA acylase in Escherichia coli.

Glutaryl 7-amino cephalosporanic acid acylase (GL-7ACA acylase) from Pseudomonas sp.130 catalyzes hydrolysis of glutaryl 7-amino cephalosporanic acid to produce 7-amino cephalosporanic acid (7-ACA). 7-ACA is the starting material for the industrial production of most cephalosparonic derivatives. Six plasmids for expression of GL-7ACA acylase were constructed and these recombin ant plasmids presented different expression characteristics in Escherichia coli. The acylase gene from plasmid pKKCA1 was inserted into plasmid pMFT7-5 and the resulting plasmid pMFT7CA1 has higher expression in E.coli. The specific activity of the crude extract of the transformant JM109(DE3)/pMFT7CA1 was near 5 u/g, so the over produced enzyme was easily purified by a single-step anion exchange column chromatography. The enzyme could be purified by immobilized ion affinity chromatography after fused by 6xHis in the N-terminal of its alpha-subunit. Because plasmid pSMLCA1 brings tc(R) and p15A origin, it is special useful plasmid in fermentation. Two secretory expression plasmids, pSUCA1S and pETCA1pelB, could secrete the acylase to periplasmic space of bacteria. The whole cells containing the secretory expression plasmid may be used for production of 7-ACA directly.