CsgI (YccT) Is a Novel Inhibitor of Curli Fimbriae Formation in Escherichia coli Preventing CsgA Polymerization and Curli Gene Expression.

Curli fimbriae are amyloids-found in bacteria (Escherichia coli)-that are involved in solid-surface adhesion and bacterial aggregation during biofilm formation. The curli protein CsgA is coded by a csgBAC operon gene, and the transcription factor CsgD is essential to induce its curli protein expression. However, the complete mechanism underlying curli fimbriae formation requires elucidation. Herein, we noted that curli fimbriae formation was inhibited by yccT-i.e., a gene that encodes a periplasmic protein of unknown function regulated by CsgD. Furthermore, curli fimbriae formation was strongly repressed by CsgD overexpression caused by a multicopy plasmid in BW25113-the non-cellulose-producing strain. YccT deficiency prevented these CsgD effects. YccT overexpression led to intracellular YccT accumulation and reduced CsgA expression. These effects were addressed by deleting the N-terminal signal peptide of YccT. Localization, gene expression, and phenotypic analyses revealed that YccT-dependent inhibition of curli fimbriae formation and curli protein expression was mediated by the two-component regulatory system EnvZ/OmpR. Purified YccT inhibited CsgA polymerization; however, no intracytoplasmic interaction between YccT and CsgA was detected. Thus, YccT-renamed CsgI (curli synthesis inhibitor)-is a novel inhibitor of curli fimbriae formation and has a dual role as an OmpR phosphorylation modulator and CsgA polymerization inhibitor.

[A Case of Immediately-Treated Internal Hernia Occurring during Chemotherapy for Liver Metastasis after Gastric GIST Resection].

A 71-year-old man underwent total gastrectomy with Roux-en-Y reconstruction for gastric GIST in October 2017. Liver metastasis was identified in June 2019, and chemotherapy with imatinib was started in July. In December, the patient presented with acute upper abdominal pain and back pain. Abdominal contrast-enhanced CT showed that the jejunum extending from the duodenal stump was dilated. In addition, part of the jejunum had a poor wall contrast effect, with ascites also found surrounding it. We suspected a strangulated ileus and immediately performed emergency surgery. We found an internal hernia with incarceration of the afferent loop at the Petersen's defect. The time from the onset of symptoms to the surgery was relatively short, and the surgery was completed with hernial repair and closure of the hernial orifice without the development of bowel necrosis; the patient's postoperative course was good. Although the frequency of internal hernia after gastrectomy is relatively low, there is a risk that it may be severe if it occurs. Therefore, care should be taken to not cause internal hernias during surgery, and an internal hernia should be considered in the event of sudden abdominal pain after gastric surgery.

Novel regulators of the csgD gene encoding the master regulator of biofilm formation in Escherichia coli K-12.

Under stressful conditions, Escherichia coli forms biofilm for survival by sensing a variety of environmental conditions. CsgD, the master regulator of biofilm formation, controls cell aggregation by directly regulating the synthesis of Curli fimbriae. In agreement of its regulatory role, as many as 14 transcription factors (TFs) have so far been identified to participate in regulation of the csgD promoter, each monitoring a specific environmental condition or factor. In order to identify the whole set of TFs involved in this typical multi-factor promoter, we performed in this study 'promoter-specific transcription-factor' (PS-TF) screening in vitro using a set of 198 purified TFs (145 TFs with known functions and 53 hitherto uncharacterized TFs). A total of 48 TFs with strong binding to the csgD promoter probe were identified, including 35 known TFs and 13 uncharacterized TFs, referred to as Y-TFs. As an attempt to search for novel regulators, in this study we first analysed a total of seven Y-TFs, including YbiH, YdcI, YhjC, YiaJ, YiaU, YjgJ and YjiR. After analysis of curli fimbriae formation, LacZ-reporter assay, Northern-blot analysis and biofilm formation assay, we identified at least two novel regulators, repressor YiaJ (renamed PlaR) and activator YhjC (renamed RcdB), of the csgD promoter.

Single-target regulators form a minor group of transcription factors in Escherichia coli K-12.

The identification of regulatory targets of all TFs is critical for understanding the entire network of the genome regulation. The lac regulon of Escherichia coli K-12 W3110 is composed of the lacZYA operon and its repressor lacI gene, and has long been recognized as the seminal model of transcription regulation in bacteria with only one highly preferred target. After the Genomic SELEX screening in vitro of more than 200 transcription factors (TFs) from E. coli K-12, however, we found that most TFs regulate multiple target genes. With respect to the number of regulatory targets, a total of these 200 E. coli TFs form a hierarchy ranging from a single target to as many as 1000 targets. Here we focus a total of 13 single-target TFs, 9 known TFs (BetI, KdpE, LacI, MarR, NanR, RpiR, TorR, UlaR and UxuR) and 4 uncharacterized TFs (YagI, YbaO, YbiH and YeaM), altogether forming only a minor group of TFs in E. coli. These single-target TFs were classified into three groups based on their functional regulation.

Digestion of peptidoglycan near the cross-link is necessary for the growth of Bacillus subtilis.

Bacterial cells are covered with peptidoglycan (PG) layer(s), serving as the cellular exoskeleton. The PG sacculus changes its shape during cell growth, and thus both the synthesis and disassembly of PG are important for cell proliferation. In Bacillus subtilis, four dl-endopeptidases (DLEPases; LytE, LytF, CwlO and CwlS) are involved in the maintenance of cell morphology. The lytE cwlO double mutant exhibits synthetic lethality and defective cell elongation, while the lytE lytF cwlS triple mutant exhibits defective cell separation, albeit with septum formation. LytE is involved in both cell separation and elongation. We propose that DLEPases have varied roles in cell separation and elongation. To determine these roles, the catalytic domain of LytE was substituted with another catalytic domain that digests the other bonds in PG. By using the chimeric enzymes, we assessed the suppression of the synthetic lethality by the cell elongation defect and the disruption of chain morphology by the cell separation defect. All the constructed chimeric enzymes suppressed the cell separation defect, restoring the chain morphology. Digestion at any position of PG broke the linkage between two daughter cells, releasing them from each other. However, only d,d-endopeptidases suppressed the lack of DLEPase in the lytE cwlO double mutant. This indicated that the release of tension on the expanding PG sacculus is not the sole essential function of DLEPases. Considering that the structure of the digested PG is important for cell elongation, the digested product might be reused in the growth process in some way.

Cross-regulation between two common ancestral response regulators, HprR and CusR, in Escherichia coli.

The uncharacterized two-component system YedVW of Escherichia coli is involved in stress response to hydrogen peroxide. To identify the H2O2-sensing role of YedV, a set of single Cys-to-Ala substitution mutants were constructed. One particular mutant with C165A substitution in the membrane domain rendered YedV inactive in H2O2-dependent transcription of its regulatory target hiuH. We then proposed to rename YedVW to HprSR (hydrogen peroxide response sensor/regulator). One unique characteristic of HprR is the overlapping of its recognition sequence with that of the Cu(II)-response two-component system regulator CusR. Towards understanding this unique regulation system, in this study we analysed the interplay between HprR and CusR with respect to transcription of hiuH, a regulatory target of HprR, and cusC, a target of CusR. Under low protein concentrations in vitro and in vivo, two regulators recognize and transcribe both hiuH and cusC promoters, albeit at different efficiency, apparently in a collaborative fashion. This is a new type of transcription regulation of the common target genes in response to different external signals. Upon increase in protein concentrations, however, HprR and CusR compete with each other in transcription of the common targets, thereby exhibiting a competitive interplay.

[The Impact of Neutrophil-Lymphocyte Ratio on the Prognosis in Patients Who Underwent Esophagectomy for Esophageal Cancer].

BACKGROUND: Thene utrophil-lymphocyteratio (NLR)reflects a patient's systemic inflammatory response. Several studies have revealed that the NLR is associated with a poor prognosis in several types of malignant tumors such as colorectal and lung cancer. The aim of this study was to evaluate the impact of preoperative NLR on the prognosis of patients with esophageal cancer. METHODS: The NLR was calculated for 93 consecutive patients with clinical Stage II or III esophageal cancer, who underwent curative esophagectomy following neoadjuvant chemotherapy between 2011 and 2013. The impact of preoperativeNLR on overall survival(OS)after esophagectomy was evaluated. The NLR cut off value was set to 2. RESULTS: The 3-year OS of patients with NLR≥2 was significantly shorter than patients with NLR<2(40.5% vs 67.9%, p=0.005). In a multivariateCox model, NLR≥2(HR: 2.342, 95%CI: 1.095-5.007, p=0.028), pathological depth of tumor(HR: 3.207, 95%CI: 1.114- 9.233, p=0.031), and an ageove r 60(HR: 2.342, 95%CI: 1.117-6.501, p=0.027)were identified as independent prognostic factors for OS after esophagectomy. CONCLUSIONS: The preoperative NLR was significantly associated with a poor prognosis in esophageal cancer patients who underwent curative esophagectomy following neoadjuvant chemotherapy.

[Laparoscopic Lateral Lymph Node Dissection for Rectal Cancer with Lateral Lymph Node Metastasis - A Case Report].

BACKGROUND: Lateral lymph node dissection(LLND)for locally advanced lower rectal cancer is the standard treatment procedure in Japan. We performed LLND with an extraperitoneal approach. Recently, we introduced laparoscopic surgery for locally advanced rectal cancer and laparoscopic LLND. We performed laparoscopic LLND in a patient havinglower rectal cancer with lateral lymph node metastasis that was detected via preoperative imaging. CASE PRESENTATION: The patient was a woman in her 50s who experienced melena and visited a physician. Colonoscopy revealed a tumor in the lower rectum and computed tomography showed lateral lymph node swelling and liver metastasis. The patient was referred to our institution and she was diagnosed with lower rectal cancer having lateral lymph node and synchronous liver metastases. We performed laparoscopic abdominoperineal resection and laparoscopic LLND. The operatingtime was 260 min, and the blood loss was 60g. CONCLUSION: The magnification of laparoscopy enables precision in the surgical operation of the narrow pelvis during lymph node dissection, allowingautonomic nerve preservation. Therefore, laparoscopic LLND is a helpful procedure in the treatment of locally advanced rectal cancer with a lateral lymph node metastasis.

Cooperative regulation of the common target genes between H2O2-sensing YedVW and Cu²âº-sensing CusSR in Escherichia coli.

YedVW is one of the uncharacterized two-component systems (TCSs) of Escherichia coli. In order to identify the regulation targets of YedVW, we performed genomic SELEX (systematic evolution of ligands by exponential enrichment) screening using phosphorylated YedW and an E. coli DNA library, and identified YedW-binding sites within three intergenic spacers, yedW-hiuH, cyoA-ampG and cusR-cusC, along the E. coli genome. Using a reporter assay system, we found that transcription of hiuH, encoding 5-hydroxyisourate hydrolase, was induced at high concentrations of either Cu(2+) or H2O2. Cu(2+)-dependent expression of hiuH was observed in the yedWV knockout mutant, but was reduced markedly in the cusRS-null mutant. However, H2O2-induced hiuH expression was observed in the cusRS-null mutant, but not in the yedWV-null mutant. Gel mobility shift and DNase I footprinting analyses showed binding of both YedW and CusR to essentially the same sequence within the hiuH promoter region. Taken together, we concluded that YedVW and CusSR formed a unique cooperative TCS pair by recognizing and regulating the same targets, but under different environmental conditions - YedVW played a role in H2O2 response regulation, whilst CusSR played a role in Cu(2+) response regulation.

Repression of flagellar genes in exponential phase by CsgD and CpxR, two crucial modulators of Escherichia coli biofilm formation.

Escherichia coli adapts its lifestyle to the variations of environmental growth conditions, swapping between swimming motility or biofilm formation. The stationary-phase sigma factor RpoS is an important regulator of this switch, since it stimulates adhesion and represses flagellar biosynthesis. By measuring the dynamics of gene expression, we show that RpoS inhibits the transcription of the flagellar sigma factor, FliA, in exponential growth phase. RpoS also partially controls the expression of CsgD and CpxR, two transcription factors important for bacterial adhesion. We demonstrate that these two regulators repress the transcription of fliA, flgM, and tar and that this regulation is dependent on the growth medium. CsgD binds to the flgM and fliA promoters around their -10 promoter element, strongly suggesting direct repression. We show that CsgD and CpxR also affect the expression of other known modulators of cell motility. We propose an updated structure of the regulatory network controlling the choice between adhesion and motility.

Genomic SELEX Screening of Regulatory Targets of Transcription Factors.

The genome of Escherichia coli K-12 is transcribed by a single species of RNA polymerase. The selectivity of transcriptional targets is determined via interaction with one of seven species of the sigma subunit and a total of approximately 300 species of transcription factor (TFs). For comprehensive identification of the regulatory targets of these two groups of regulatory proteins on the genome, we developed an in vitro approach, "Genomic SELEX" (gSELEX) screening. Here we describe a detailed protocol of the gSELEX screening system, which uses purified regulatory proteins and fragments of genomic DNA from E. coli. Moreover, we describe methods and examples of results using cell-free synthetic proteins.

Identification of the set of genes, including nonannotated morA, under the direct control of ModE in Escherichia coli.

ModE is the molybdate-sensing transcription regulator that controls the expression of genes related to molybdate homeostasis in Escherichia coli. ModE is activated by binding molybdate and acts as both an activator and a repressor. By genomic systematic evolution of ligands by exponential enrichment (SELEX) screening and promoter reporter assays, we have identified a total of nine operons, including the hitherto identified modA, moaA, dmsA, and napF operons, of which six were activated by ModE and three were repressed. In addition, two promoters were newly identified and direct transcription of novel genes, referred to as morA and morB, located on antisense strands of yghW and torY, respectively. The morA gene encodes a short peptide, MorA, with an unusual initiation codon. Surprisingly, overexpression of the morA 5' untranslated region exhibited an inhibitory influence on colony formation of E. coli K-12.

Screening of promoter-specific transcription factors: multiple regulators for the sdiA gene involved in cell division control and quorum sensing.

Prokaryotic DNA-binding transcription factors (TFs) bind in close vicinity of the promoter and regulate transcription through interplay with the DNA-dependent RNA polymerase. Promoters associated with the genes involved in stress response have recently been found to be under the control of multiple regulators, each monitoring one specific environmental condition or factor. In order to identify TFs involved in regulation of one specific promoter, we have developed a PS-TF (promoter-specific TF) screening system, in which the binding of purified TFs to a test promoter was analysed by gel-shift assay. This PS-TF screening system was applied for detection of TFs involved in regulation of the promoter for the Escherichia coli sdiA gene encoding the master regulator of cell division and quorum sensing. After screening of a total of 191 purified TFs (two-thirds of the predicted E. coli TFs), at least 15 TFs have been identified to bind to the sdiA promoter, including five two-component system (TCS) regulators, ArcA, CpxR, OmpR, RcsB and TorR. In this study, we focus on these five TFs for detailed analysis of their regulatory roles in vivo. Under normal growth conditions in LB medium, all these TFs repressed the sdiA promoter and the repression levels correlated with their intracellular levels. Taken together, we propose that these TCS regulators repress transcription in vivo of the sdiA gene, ultimately leading to suppression of cell division.

Roles of methionine and cysteine residues of the Escherichia coli sensor kinase HprS in reactive chlorine species sensing.

Sensor histidine kinase HprS, an oxidative stress sensor of Escherichia coli, senses reactive oxygen species (ROS) and reactive chlorine species (RCS), and is involved in the induction of oxidatively damaged protein repair periplasmic enzymes. We reinvestigated the roles of six methionine and four cysteine residues of HprS in the response to HClO, an RCS. The results of site-directed mutagenesis revealed that methionine residues in periplasmic and cytoplasmic regions (Met225) are involved in HprS activation. Interestingly, the Cys165Ser substitution reduced HprS activity, which was recovered by an additional Glu22Cys substitution. Our results demonstrate that the position of the inner membrane cysteine residues influences the extent of HprS activation in HClO sensing.

Novel regulation targets of the metal-response BasS-BasR two-component system of Escherichia coli.

The BasS-BasR two-component system is known as an iron- and zinc-sensing transcription regulator in Escherichia coli, but so far only a few genes have been identified to be under the direct control of phosphorylated BasR. Using Genomic SELEX (systematic evolution of ligands by exponential enrichment) screening, we have identified a total of at least 38 binding sites of phosphorylated BasR on the E. coli genome, and based on the BasR-binding sites, have predicted more than 20 novel targets of regulation. By DNase I footprint analysis for high-affinity BasR-binding sites, a direct repeat of a TTAAnnTT sequence was identified as the BasR box. Transcription regulation in vivo of the target genes was confirmed after Northern blot analysis of target gene mRNAs from both wild-type E. coli and an otherwise isogenic basR deletion mutant. The BasR regulon can be classified into three groups of genes: group 1 includes the genes for the formation and modification of membrane structure; group 2 includes genes for modulation of membrane functions; and group 3 includes genes for stress-response cell functions, including csgD, the master regulator of biofilm formation.

Case Report: A Very Low Birth Weight Female Infant With Congenital Bilateral Periventricular Leukomalacia, Born to a Mother With Coronavirus Disease 2019.

A 26-year-old primipara woman with COVID-19 performed an emergency Cesarean section due to further hypoxemia at 28 weeks 5/7 days gestation. The female neonate was born weighing 1,347 gram with an Apgar score of four at 1 min, three at 5 min, and eight at 10 min. RT-PCR from nasopharyngeal swabs for COVID-19 were performed at birth, 24 h, and 48 h after birth, all of which were negative. On head ultrasound bilateral cystic lesions were found in the anterior horn of the lateral ventricles at birth. A brain magnetic resonance imaging (MRI) test at 56 days of life (corrected 36 weeks and 6/7 days) revealed cystic lesions with T1 low signal, T2 high signal, and T2 Flair high signal around the anterior horn of the lateral ventricle and We diagnose it as Grade 2 periventricular leukomalacia (PVL). She was discharged on day 64 of life, with no abnormality on exam. While the majority of neonates born to women with COVID-19 during pregnancy have favorable outcome, we report a case of a neonate with Grade 2 periventricular leukomalacia and this should prompt clinicians to monitor fetal cerebral function and structure shortly after birth.

Role of the biofilm master regulator CsgD in cross-regulation between biofilm formation and flagellar synthesis.

CsgD, the master regulator of biofilm formation, activates the synthesis of curli fimbriae and extracellular polysaccharides in Escherichia coli. To obtain insights into its regulatory role, we have identified a total of 20 novel regulation target genes on the E. coli genome by using chromatin immunoprecipitation (ChIP)-on-chip analysis with a high-density DNA microarray. By DNase I footprinting, the consensus CsgD-binding sequence predicted from a total of 18 target sites was found to include AAAAGNG(N(2))AAAWW. After a promoter-lacZ fusion assay, the CsgD targets were classified into two groups: group I genes, such as fliE and yhbT, are repressed by CsgD, while group II genes, including yccT and adrA, are activated by CsgD. The fliE and fliEFGH operons for flagellum formation are directly repressed by CsgD, while CsgD activates the adrA gene, which encodes an enzyme for synthesis of cyclic di-GMP, a bacterial second messenger, which in turn inhibits flagellum production and rotation. Taking these findings together, we propose that the cell motility for planktonic growth is repressed by CsgD, thereby promoting the switch to biofilm formation.

L1 Cell adhesion molecule (L1CAM) expression at the cancer invasive front is a novel prognostic marker of pancreatic ductal adenocarcinoma.

BACKGROUND AND OBJECTIVES: Pancreatic ductal adenocarcinoma (PDAC) is one of the most extremely aggressive cancers with a poor prognosis after curative resection. L1 cell adhesion molecule (L1CAM) is a 200-220 kDa type I transmembrane glycoprotein of the immunoglobulin superfamily, which has been shown to affect the prognosis of several cancers. No clinicopathological significance of L1CAM expression has been examined at the invasive front of PDAC. In this study, we examined the relationship between L1CAM expression and clinicopathological features in PDAC by immunohistochemistry. METHODS: One hundred seven surgically resected specimens of PDAC were immunohistochemically examined using a monoclonal antibody against L1CAM. RESULTS: Positive expression of L1CAM was found in 23 of 107 cases with PDAC. In most cases (21/23), L1CAM expression was localized at the invasive front of the tumor tissue. Positive expression of L1CAM was significantly correlated with the histological grade, lymph node involvement, and distant metastasis. In univariate analysis, a positive expression of L1CAM was associated with short overall survival (P = 0.0002), and this was significant in multivariate analysis (P = 0.009). CONCLUSIONS: L1CAM could play an important role in the invasive process in vivo, and is thought to be a good indicator of prognosis in PDAC.

[Two cases of complete response of primary esophageal carcinoma treated with 5-FU/CDDP as neoadjuvant chemotherapy].

CASE 1: A 67-year-old man with lower thoracic esophageal carcinoma, T2N0M0, cStage II, underwent neoadjuvant chemotherapy (NAC) with 5-FU/CDDP. After 2 courses of NAC, radical resection of the esophageal carcinoma was performed. Primary tumor was not palpable, and lymph node swelling was not found in the resected specimens. Pathologic examination of the resected specimens revealed no malignant cells in the esophagus. Histologic effect of the NAC was grade 3. We obtained down-staging of carcinoma in T0N0M0, fStage 0. CASE 2: A 58-year-old man with thoracic esophageal cancer, T3N2M0, cStage III, underwent NAC with 5-FU/CDDP. After 2 courses of NAC, radical resection of the esophageal carcinoma was performed. Primary tumor was not found in the resected specimens. Pathologic examination of the resected specimens revealed only an irregular fibrosis of esophageal wall, and no malignant cells in the esophagus. Two lymph node metastasis and surrounding fibrosis was found. We obtained down-staging of carcinoma in T0N2M0, fStage II. We report two cases of complete response of primary esophageal carcinoma treated with 5-FU/CDDP as neoadjuvant chemotherapy.

Single-Target Regulators Constitute the Minority Group of Transcription Factors in Escherichia coli K-12.

The identification of regulatory targets of all transcription factors (TFs) is critical for understanding the entire network of genome regulation. A total of approximately 300 TFs exist in the model prokaryote Escherichia coli K-12, but the identification of whole sets of their direct targets is impossible with use of in vivo approaches. For this end, the most direct and quick approach is to identify the TF-binding sites in vitro on the genome. We then developed and utilized the gSELEX screening system in vitro for identification of more than 150 E. coli TF-binding sites along the E. coli genome. Based on the number of predicted regulatory targets, we classified E. coli K-12 TFs into four groups, altogether forming a hierarchy ranging from a single-target TF (ST-TF) to local TFs, global TFs, and nucleoid-associated TFs controlling as many as 1,000 targets. Using the collection of purified TFs and a library of genome DNA segments from a single and the same E. coli K-12, we identified here a total of 11 novel ST-TFs, CsqR, CusR, HprR, NorR, PepA, PutA, QseA, RspR, UvrY, ZraR, and YqhC. The regulation of single-target promoters was analyzed in details for the hitherto uncharacterized QseA and RspR. In most cases, the ST-TF gene and its regulatory target genes are adjacently located on the E. coli K-12 genome, implying their simultaneous transfer in the course of genome evolution. The newly identified 11 ST-TFs and the total of 13 hitherto identified altogether constitute the minority group of TFs in E. coli K-12.