bluuebunny/crossref_metadata_2025_split huggingface dataset:
An RpoH-Like Heat Shock Sigma Factor Is Involved in Stress Response and Virulence inBrucella melitensis16M
Authors: Delory Marie , Hallez Régis , Letesson Jean-Jacques , De Bolle Xavier 
Published: October 2006

ABSTRACTB. melitensis16M genome analysis revealed the presence of six putative sigma factor-encoding genes:rpoD,rpoH1,rpoH2,rpoE1,rpoE2, andrpoN. We mutated all these genes exceptrpoD. Phenotypic analysis of the mutants reveals that a strain carrying anrpoH2null mutation (ΔrpoH2) is impaired for growth at 21 and 42°C and shows increased sensitivity to hydrogen peroxide. Compared to the wild-type strain, the ΔrpoH2mutant is attenuated in all virulence models tested. Three other null mutants (ΔrpoH1, ΔrpoE1, and ΔrpoE2mutants) are also defective for survival in mice at 4 weeks postinfection. We also demonstrated thatrpoH2deletion strongly reduces the expression of two major virulence factors inB. melitensis, the type IV secretion system and the flagellum.
O Acetylation of the Enterobacterial Common Antigen Polysaccharide Is Catalyzed by the Product of the
yiaH
Gene of
Escherichia coli
K-12
Authors: Kajimura Junko , Rahman Arifur , Hsu James , Evans Matthew R. , Gardner Kevin H. , Rick Paul D. 
Published: October 2006

ABSTRACT

The carbohydrate component of the enterobacterial common antigen (ECA) of
Escherichia coli
K-12 occurs primarily as a water-soluble cyclic polysaccharide located in the periplasm (ECA
CYC
) and as a phosphoglyceride-linked linear polysaccharide located on the cell surface (ECA
PG
). The polysaccharides of both forms are comprised of the amino sugars
N
-acetyl-
d
-glucosamine (GlcNAc),
N
-acetyl-
d
-mannosaminuronic acid (ManNAcA), and 4-acetamido-4,6-dideoxy-
d
-galactose (Fuc4NAc). These amino sugars are linked to one another to form trisaccharide repeat units with the structure →3-α-
d
-Fuc4NAc-(1→4)-β-
d
-ManNAcA-(1→4)-α-
d
-GlcNAc-(1→. The hydroxyl group in the 6 position of the GlcNAc residues of both ECA
CYC
and ECA
PG
are nonstoichiometrically esterified with acetyl groups. Random transposon insertion mutagenesis of
E. coli
K-12 resulted in the generation of a mutant defective in the incorporation of
O
-acetyl groups into both ECA
CYC
and ECA
PG
. This defect was found to be due to an insertion of the transposon into the
yiaH
locus, a putative gene of unknown function located at 80.26 min on the
E. coli
chromosomal map. Bioinformatic analyses of the predicted
yiaH
gene product indicate that it is an integral inner membrane protein that is a member of an acyltransferase family of enzymes found in a wide variety of organisms. The results of biochemical and genetic experiments presented here strongly support the conclusion that
yiaH
encodes the
O
-acetyltransferase responsible for the incorporation of
O
-acetyl groups into both ECA
CYC
and ECA
PG
. Accordingly, we propose that this gene be designated
wecH
.
Evolution of Transmembrane Protein Kinases Implicated in Coordinating Remodeling of Gram-Positive Peptidoglycan: Inside versus Outside
Authors: Jones Greg , Dyson Paul 
Published: October 2006

ABSTRACT

Members of a family of serine/threonine protein kinases (STPKs), unique to gram-positive bacteria, comprise an intracellular kinase domain and reiterated extracellular PASTA (for “penicillin-binding protein and serine/threonine kinase associated”) domains. PASTA domains exhibit low affinity for β-lactam antibiotics that are structurally similar to their likely normal ligands: stem peptides of unlinked peptidoglycan. The PASTA-domain STPKs are found in the actinobacteria and firmicutes and, as exemplified by PknB of
Mycobacterium tuberculosis
, they are functionally implicated in aspects of growth, cell division, and development. Whereas the kinase domains are well conserved, there is a wide divergence in the sequences of the multiple PASTA domains. Closer inspection reveals position-dependent evolution of individual PASTA domains: a domain at one position within a gene has a close phylogenetic relationship with a domain at a similar position in an orthologous gene, whereas neighboring domains have clearly diverged one from one another. A similar position-dependent relationship is demonstrated in the second family of proteins with multiple PASTA domains: the high-molecular-weight type II penicillin-binding protein (PBP2x) family. These transpeptidases are recruited to the division site by a localized pool of unlinked peptidoglycan. We infer that protein localization is guided by low-affinity interactions between structurally different unlinked peptidoglycan stem peptides and individual PASTA domains. The STPKs possess a greater multiplicity and diversity of PASTA domains, allowing interactions with a wider range of stem-peptide ligands. These interactions are believed to activate the intracellular kinase domain, allowing an STPK to coordinate peptidoglycan remodeling and reproduction of a complex cell wall structure.
Novel Conserved Assembly Factor of the Bacterial Flagellum
Authors: Titz Björn , Rajagopala Seesandra V. , Ester Claudia , Häuser Roman , Uetz Peter 
Published: October 2006

ABSTRACT

TP0658 (FliW) and its orthologs, conserved proteins of unknown function in
Treponema pallidum
and other species, interact with a C-terminal region of flagellin (FlaB1-3 in
T. pallidum
; FliC in most other species). Mutants of orthologs in
Bacillus subtilis
and
Campylobacter jejuni
(
yviF
, CJ1075) showed strongly reduced motility. TP0658 stabilizes flagellin in a way similar to FliS, suggesting that TP0658 is a conserved assembly factor for the bacterial flagellum.
A New GntR Family Transcriptional Regulator inStreptomyces coelicolorIs Required for Morphogenesis and Antibiotic Production and Controls Transcription of an ABC Transporter in Response to Carbon Source
Authors: Hillerich Brandan , Westpheling Janet 
Published: October 2006

ABSTRACTWe recently reported the isolation and initial characterization of a transposon-generated mutation that resulted in defects in both morphogenesis and antibiotic production inStreptomyces coelicolor. The insertion identified the SCO7168 open reading frame whose predicted product is a GntR family transcriptional regulator. Here, we show that this gene acts to repress transcription of itself as well as a series of genes immediately adjacent to it on theS. coelicolorchromosome that likely encode an ATP-binding cassette (ABC)-type transporter for carbohydrate uptake. Transcription of this transporter is strongly induced by growth on relatively poor carbon sources such as trehalose and melibiose and weakly induced by lactose and glycerol but not glucose, and induction is not repressed by the presence of glucose. Constructed deletions of the ABC transporter itself resulted in the suppression of the original transposon mutation, suggesting that inappropriate expression of the ABC transporter is responsible, at least in part, for the mutant phenotype. Because this transporter responds to the presence of α-glucosides and has similarity to two other carbohydrate transporters of this class, we have named the genes of the transporteragl3E,agl3F, andagl3Gand the GntR-like protein that regulates transcription of the transporteragl3Rin accordance with established nomenclature. We suggest thatagl3Ris one of a number of homologous proteins inStreptomyces(there are 57 putative GntR family regulators in theS. coelicolorgenome) that respond to nutritional and/or environmental signals to control genes that affect morphogenesis and antibiotic production.
Selective Promoter Recognition by Chlamydial σ28Holoenzyme
Authors: Shen Li , Feng Xiaogeng , Yuan Yuan , Luo Xudong , Hatch Thomas P. , Hughes Kelly T. , Liu Jun S. , Zhang You-xun 
Published: October 2006

ABSTRACTThe σ transcription factor confers the promoter recognition specificity of RNA polymerase (RNAP) in eubacteria.Chlamydia trachomatishas three known sigma factors, σ66, σ54, and σ28. We developed two methods to facilitate the characterization of promoter sequences recognized byC. trachomatisσ28(σ28Ct). One involved the arabinose-induced expression of plasmid-encoded σ28Ctin a strain ofEscherichia colidefective in the σ28structural gene,fliA. The second was an analysis of transcription in vitro with a hybrid holoenzyme reconstituted withE. coliRNAP core and recombinant σ28Ct. These approaches were used to investigate the interactions of σ28Ctwith the σ28Ct-dependenthctBpromoter and selectedE. coliσ28(σ28Ec)-dependent promoters, in parallel, compared with the promoter recognition properties of σ28EC. Our results indicate that RNAP containing σ28Cthas at least three characteristics: (i) it is capable of recognizing some but not all σ28EC-dependent promoters; (ii) it can distinguish different promoter structures, preferentially activating promoters with upstream AT-rich sequences; and (iii) it possesses a greater flexibility than σ28ECin recognizing variants with different spacing lengths separating the −35 and −10 elements of the core promoter.
Identification and Characterization of BicistronicspeBandprsAGene Expression in the Group A Streptococcus
Authors: Ma Yongsheng , Bryant Amy E. , Salmi Dan B. , Hayes-Schroer Susan M. , McIndoo Eric , Aldape Michael J. , Stevens Dennis L. 
Published: October 2006

ABSTRACTSevere, invasive group A streptococcal infections have reemerged worldwide, and extracellular toxins, including streptococcal pyrogenic exotoxin B (SpeB), have been implicated in pathogenesis. The genetic regulation of SpeB is not fully understood, and the mechanisms involved in the processing of the protoxin to its enzymatically active form have not been definitively established. The present work demonstrated that the genes encoding SpeB (speB) and a peptidyl-prolyl isomerase (prsA) constitute an operon with transcription initiated from two promoters upstream ofspeB. Further, thespeB-prsAoperon was transcribed as a bicistronic mRNA. This finding is in contrast to the generally accepted notion thatspeBis transcribed only as a monocistronic gene. In addition,prsAhas its own promoter, and transcription from this promoter starts in early log phase, prior to the transcription ofspeB. Genomic disruption ofprsAdecreased the production of enzymatically active SpeB but not the level of the pro-SpeB zymogen. Taken together, these results demonstrate thatprsAis required for production of fully mature, enzymatically active SpeB.
Protein Disulfide Isomerase Expression Is Related to the Invasive Properties of Malignant Glioma
Authors: Goplen Dorota , Wang Jian , Enger Per Ø. , Tysnes Berit B. , Terzis A.J.A. , Laerum Ole D. , Bjerkvig Rolf 
Published: October 2006

Abstract
By serial transplantation of human glioblastoma biopsies into the brain of immunodeficient nude rats, two different tumor phenotypes were obtained. Initially, the transplanted xenografts displayed a highly invasive phenotype that showed no signs of angiogenesis. By serial transplantation in animals, the tumors changed to a less invasive, predominantly angiogenic phenotype. To identify novel proteins related to the invasive phenotype, the xenografts were analyzed using a global proteomics approach. One of the identified proteins was protein disulfide isomerase (PDI) A6 precursor. PDI is a chaperone protein that mediates integrin-dependent cell adhesion. It is both present in the cytosol and at the cell surface. We show that PDI is strongly expressed on invasive glioma cells, in both xenografts and at the invasive front of human glioblastomas. Using an in vitro migration assay, we also show that PDI is expressed on migrating glioma cells. To determine the functional significance of PDI in cell migration, we tested the effect of a PDI inhibitor, bacitracin, and a PDI monoclonal antibody on glioma cell migration and invasion in vitro. Both tumor spheroids derived from human glioblastoma xenografts in nude rat brain and cell line spheroids were used. The PDI antibody, as well as bacitracin, inhibited tumor cell migration and invasion. The anti-invasive effect of bacitracin was reversible after withdrawal of the inhibitor, indicating a specific, nontoxic effect. In conclusion, using a global proteomics approach, PDI was identified to play an important role in glioma cell invasion, and its action was effectively inhibited by bacitracin. (Cancer Res 2006; 66(20): 9895-902)
RET Is Constitutively Activated by Novel Tandem Mutations that Alter the Active Site Resulting in Multiple Endocrine Neoplasia Type 2B
Authors: Cranston Aaron N. , Carniti Cristiana , Oakhill Kim , Radzio-Andzelm Elzbieta , Stone Eric A. , McCallion Andrew S. , Hodgson Shirley , Clarke Sue , Mondellini Piera , Leyland Jean , Pierotti Marco A. , Whittaker Joanne , Taylor Susan S. , Bongarzone Italia , Ponder Bruce A.J. 
Published: October 2006

Abstract
Constitutive activation of the RET receptor tyrosine kinase underlies the genesis and progression of multiple endocrine neoplasia type 2 (MEN 2), a dominantly inherited cancer predisposition. Importantly, although kinase activation represents a common theme in neoplasias, not all activating mutations are functionally equivalent. Consistent with this, we ascertained a patient with classical features of MEN 2B, but lacking either of the classical mutations in RET (M918T or A883F). Instead, the patient harbors a novel pair of germ line missense mutations in cis at codons 804 and 805. We evaluated the potential physiochemical effects of these substitutions in silico, predicting both to be moderately deleterious in isolation, but severely deleterious in combination. Consistent with this postulate, we show that the identified tandem mutations (V804M/E805K) are biologically active, transforming cells in culture and that their transforming capacity in combination is distinctly synergistic. Furthermore, the V804M/E805K tandem lesion confers resistance to the small molecule receptor tyrosine kinase inhibitor, PP1, suggesting a mode of action distinct from that known for classical MEN 2B mutations. To address this question, we used homology molecular modeling in silico to model the active site of RET. We predict that RET804 constitutes a critical gatekeeper residue that, when mutated in combination with RET805, induces a conformational change in the hinge region that locks the active site in a position permissive for ATP hydrolysis. Our findings have implications both in the clinic and in the successful development of novel kinase-targeted anticancer drugs. (Cancer Res 2006; 66(20): 10179-87)
Transforming Growth Factor β Receptor Type II Inactivation Induces the Malignant Transformation of Intestinal Neoplasms Initiated by Apc Mutation
Authors: Muñoz Nina M. , Upton Melissa , Rojas Andres , Washington M. Kay , Lin Li , Chytil Anna , Sozmen Elif G. , Madison Blair B. , Pozzi Ambra , Moon Randall T. , Moses Harold L. , Grady William M. 
Published: October 2006

Abstract
The transforming growth factor-β (TGF-β) signaling pathway is a tumor-suppressor pathway that is commonly inactivated in colon cancer. TGF-β is a secreted ligand that mediates its effects through a transmembrane heteromeric receptor complex, which consists of type I (TGFBR1) and type II subunits (TGFBR2). Approximately 30% of colon cancers carry TGFBR2 mutations, demonstrating that it is a common target for mutational inactivation in this cancer. To assess the functional role of TGFBR2 inactivation in the multistep progression sequence of colon cancer, we generated a mouse model that recapitulates two common genetic events observed in human colon cancer by mating Apc1638N/wt mice with mice that are null for Tgfbr2 in the intestinal epithelium, Villin-Cre;Tgfbr2E2flx/E2flx mice. In this model, we observed a dramatic increase in the number of intestinal adenocarcinomas in the Apc1638N/wt;Villin-Cre;Tgfbr2E2flx/E2flx mice (called Apc1638N/wt;Tgfbr2IEKO) compared with those mice with intact Tgfbr2 (Apc1638N/wt;Tgfbr2E2flx/E2flx). Additionally, in vitro analyses of epithelial tumor cells derived from the Apc1638N/wt;Tgfbr2IEKO mice showed enhanced expression and activity of matrix metalloproteinase MMP-2 and MMP-9, as well as increased TGF-β1 secretion in the conditioned medium. Similarly, primary tumor tissues from the Apc1638N/wt;Tgfbr2IEKO mice also showed elevated amounts of TGF-β1 as well as higher MMP-2 activity in comparison with Apc1638N/wt;Tgfbr2E2flx/E2flx–derived tumors. Thus, loss of TGFBR2 in intestinal epithelial cells promotes the invasion and malignant transformation of tumors initiated by Apc mutation, providing evidence that Wnt signaling deregulation and TGF-β signaling inactivation cooperate to drive the initiation and progression, respectively, of intestinal cancers in vivo. (Cancer Res 2006; 66(20): 9837-44)
Caveolin-1 (CAV1) Is a Target of EWS/FLI-1 and a Key Determinant of the Oncogenic Phenotype and Tumorigenicity of Ewing's Sarcoma Cells
Authors: Tirado Oscar M. , Mateo-Lozano Silvia , Villar Joaquín , Dettin Luis E. , Llort Anna , Gallego Soledad , Ban Jozef , Kovar Heinrich , Notario Vicente 
Published: October 2006

Abstract
Tumors of the Ewing's sarcoma family (ESFT), such as Ewing's sarcoma (EWS) and primitive neuroectodermal tumors (PNET), are highly aggressive malignancies predominantly affecting children and young adults. ESFT express chimeric transcription factors encoded by hybrid genes fusing the EWS gene with several ETS genes, most commonly FLI-1. EWS/FLI-1 proteins are responsible for the malignant phenotype of ESFT, but only few of their transcriptional targets are known. Using antisense and short hairpin RNA–mediated gene expression knockdown, array analyses, chromatin immunoprecipitation methods, and reexpression studies, we show that caveolin-1 (CAV1) is a new direct target of EWS/FLI-1 that is overexpressed in ESFT cell lines and tumor specimens and is necessary for ESFT tumorigenesis. CAV1 knockdown led to up-regulation of Snail and the concomitant loss of E-cadherin expression. Consistently, loss of CAV1 expression inhibited the anchorage-independent growth of EWS cells and markedly reduced the growth of EWS cell–derived tumors in nude mice xenografts, indicating that CAV1 promotes the malignant phenotype in EWS carcinogenesis. Reexpression of CAV1 or E-cadherin in CAV1 knockdown EWS cells rescued the oncogenic phenotype of the original EWS cells, showing that the CAV1/Snail/E-cadherin pathway plays a central role in the expression of the oncogenic transformation functions of EWS/FLI-1. Overall, these data identify CAV1 as a key determinant of the tumorigenicity of ESFT and imply that targeting CAV1 may allow the development of new molecular therapeutic strategies for ESFT patients. (Cancer Res 2006; 66(20): 9937-47)
Comparative Proteomic Profiles of Meningioma Subtypes
Authors: Okamoto Hiroaki , Li Jie , Vortmeyer Alexander O. , Jaffe Howard , Lee Youn-Soo , Gläsker Sven , Sohn Tae-Sung , Zeng Weifen , Ikejiri Barbara , Proescholdt Martin A. , Mayer Christina , Weil Robert J. , Oldfield Edward H. , Zhuang Zhengping 
Published: October 2006

Abstract
Meningiomas are classified into three groups (benign, atypical, and anaplastic) based on morphologic characteristics. Atypical meningiomas, which are WHO grade 2 tumors, and anaplastic meningiomas, which are WHO grade 3 tumors, exhibit an increased risk of recurrence and premature death compared with benign WHO grade 1 tumors. Although atypical and anaplastic meningiomas account for &lt;10% of all of meningiomas, it can be difficult to distinguish them from benign meningiomas by morphologic criteria alone. We used selective tissue microdissection to examine 24 human meningiomas and did two-dimensional gel electrophoresis to determine protein expression patterns. Proteins expressed differentially by meningiomas of each WHO grade were identified and sequenced. Proteomic analysis revealed protein expression patterns unique to WHO grade 1, 2, and 3 meningiomas and identified 24 proteins that distinguish each subtype. Fifteen proteins showed significant changes in expression level between benign and atypical meningiomas, whereas nine distinguished atypical from anaplastic meningiomas. Differential protein expression was confirmed by Western blotting and immunohistochemistry. We established differential proteomic profiles that characterize and distinguish meningiomas of increasing grades. The proteins and proteomic profiles enhance understanding of the pathogenesis of meningiomas and have implications for diagnosis, prognosis, and treatment. (Cancer Res 2006; 66(20): 10199-204)
Induction of Therapeutically Relevant Cytotoxic T Lymphocytes in Humans by Percutaneous Peptide Immunization
Authors: Yagi Hiroaki , Hashizume Hideo , Horibe Takahiro , Yoshinari Yasushi , Hata Maki , Ohshima Akihiro , Ito Taisuke , Takigawa Masahiro , Shibaki Akihiko , Shimizu Hiroshi , Seo Naohiro 
Published: October 2006

AbstractPercutaneous peptide immunization (PPI) is a simple and noninvasive immunization approach to induce potent CTL responses by peptide delivery via skin with the stratum corneum removed. After such a barrier disruption in human skin, epidermal Langerhans cells, although functionally matured through the up-regulation of HLA expression and costimulatory molecules, were found to emigrate with a reduced number of dendrites. CD8+ populations binding to MHC-peptide tetramers/pentamers and producing IFN-γ appeared in the blood after PPI with HLA class I–restricted antigenic peptides. PPI with melanoma-associated peptides reduced the lesion size and suppressed further development of tumors in four of seven patients with advanced melanoma. These beneficial effects were accompanied by the generation of circulating CTLs with in vitro cytolytic activity and extensive infiltration of tetramer/pentamer-binding cells into regressing lesions. PPI elicited neither local nor systemic toxicity or autoimmunity, except for vitiligo, in patients with melanoma. Therefore, PPI represents a novel therapeutic intervention for cancer in the clinical setting. (Cancer Res 2006; 66(20): 10136-44)
Activation of EDTA-Resistant Gelatinases in Malignant Human Tumors
Authors: Chen Donghai , Kennedy Alanna , Wang Jaw-Yuan , Zeng Wei , Zhao Qiang , Pearl Michael , Zhang Mengzhen , Suo Zhenhe , Nesland Jahn M. , Qiao Yuhuan , Ng Ah-Kau , Hirashima Naoko , Yamane Tetsu , Mori Yoshiyuki , Mitsumata Masako , Ghersi Giulio , Chen Wen-Tien 
Published: October 2006

Abstract
Among the many proteases associated with human cancer, seprase or fibroblast activation protein α, a type II transmembrane glycoprotein, has two types of EDTA-resistant protease activities: dipeptidyl peptidase and a 170-kDa gelatinase activity. To test if activation of gelatinases associated with seprase could be involved in malignant tumors, we used a mammalian expression system to generate a soluble recombinant seprase (r-seprase). In the presence of putative EDTA-sensitive activators, r-seprase was converted into 70- to 50-kDa shortened forms of seprase (s-seprase), which exhibited a 7-fold increase in gelatinase activity, whereas levels of dipeptidyl peptidase activity remained unchanged. In malignant human tumors, seprase is expressed predominantly in tumor cells as shown by in situ hybridization and immunohistochemistry. Proteins purified from experimental xenografts and malignant tumors using antibody- or lectin-affinity columns in the presence of 5 mmol/L EDTA were assayed for seprase activation in vivo. Seprase expression and activation occur most prevalently in ovarian carcinoma but were also detected in four other malignant tumor types, including adenocarcinoma of the colon and stomach, invasive ductal carcinoma of the breast, and malignant melanoma. Together, these data show that, in malignant tumors, seprase is proteolytically activated to confer its substrate specificity in collagen proteolysis and tumor invasion. (Cancer Res 2006; 66(20): 9977-85)