DsbA is the major oxidase responsible for generation of disulfide bonds in proteins of E. coli envelope. In the present work we provided the first detailed characterization of disulfide exchange between DsbA and its natural substrate, HtrA protease. We demonstrated that HtrA oxidation relies on DsbA, both in vivo and in vitro. We followed the disulfide exchange between these proteins spectrofluorimetrically and found that DsbA oxidizes HtrA with a 1 : 1 stoichiometry. The calculated second-order apparent rate constant (kapp) of this reaction was 3.3 × 104 ± 0.6 × 104 M-1s-1. This value was significantly higher than the values obtained for nonfunctional disulfide exchanges between DsbA and DsbC or DsbD and it was comparable to the kapp values calculated for in vitro oxidation of certain non-natural DsbA substrates of eukaryotic origin.
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Rheumatoid arthritis (RA) is a chronic, systemic inflammatory disease which affects approximately 1% of the population worldwide. Recent research on the role of heat shock proteins (Hsps) in RA development indicates that they may have pro- or anti-inflammatory effect, most probably via modulating cytokine secretion. We investigated type Th1 (INFγ, TNFα, IL-2) and type Th2 (IL-10, IL-6, IL-4) cytokine levels in sera of RA patients and healthy controls, using flow cytometric bead array assay, and searched for correlations between the cytokine levels and serum antibodies against bacterial (DnaJ) and human (Hdj1, Hdj2 and Hdj3) Hsp40 proteins, as well as clinical and laboratory parameters. The levels of all cytokines studied were significantly increased in RA patients; the highest increase relative to healthy controls (7-fold) was observed for IL-6 and its levels correlated positively with the antibodies directed to DnaJ and to the C-terminal domain of Hdj2, and with diagnostic parameters (DAS 28, Steinbrocker RTG criteria, ARA/7, ESR, TEN, SW and GH). INFγ levels correlated negatively with DAS 28, ESR, TEN and SW. No correlations were found for TNFα, IL-2 or IL-4. Our results support the hypothesis of Hsp40 involvement in RA as well as indicate that IL-6 serum level is a good marker of the RA activity.
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Escherichia coli small heat shock proteins, IbpA/B, function as molecular chaperones and protect misfolded proteins against irreversible aggregation. IbpA/B are induced during overproduction of recombinant proteins and bind to inclusion bodies in E. coli cells. We investigated the effect of ΔibpA/B mutation on formation of inclusion bodies and biological activity of enzymes sequestered in the aggregates in E. coli cells. Using three different recombinant proteins: Cro-β-galactosidase, β-lactamase and rat rHtrA1 we demonstrated that deletion of the ibpA/B operon did not affect the level of produced inclusion bodies. However, in aggregates containing IbpA/B a higher enzymatic activity was detected than in the IbpA/B-deficient inclusion bodies. These results confirm that IbpA/B protect misfolded proteins from inactivation in vivo.
Background: Angiogenesis is a key process in the development of a malignant tumor, enabling both growth of primary lesion and spread of metastases. Most potent stimulators of normal and pathological angiogenesis are proteins of the vascular endothelial growth factor (VEGF) family. Regulation of angiogenesis process is also mediated by neuropilin- 1 (NP-1), as coreceptor VEGFR-2. NP-1 plays a crucial role controlling both normal angiogenesis during embryonal development and pathological angiogenesis in malignant tumors. The aim of this paper was to assess NP-1 expression in ovarian cancer and to analyze correlations between NP-1 expression and selected clinical-pathological factors in a group of ovarian cancer patients. Material and method: Analyzed was the relative level of NP-1 in 168 surgical specimens collected during surgical procedures performed at the Department of Oncologic Gynecology of Medical University in Gdańsk. Tissue samples included: 32 healthy tissues, 42 benign tumors, 10 borderline tumors, 76 ovarian cancers, 8 metastatic tumors. Relative NP-1 level was assessed using Western blotting technology. Results: Overexpression of NP-1 was seen significantly more often in early clinical stages of ovarian cancer (p=0.01), in cancers other than serous (p=0.04) and in patients with peritoneal exudate (p=0.03). Log-rank test did not reveal any significant correlation between NP-1 expression and favorable response to chemotherapy, disease-free survival or total survival time. Conclusions. Elevated NP-1 level seen in initial clinical stages of ovarian cancer may indicate crucial role of neoangiogenesis in the early phase of tumor development.
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Hsp70 (DnaK) is a highly conserved molecular chaperone present in bacteria, eukaryotes, and some archaea. In a previous work we demonstrated that DnaK from the archaeon Methanosarcina mazei (DnaKMm) and the DnaK from the bacterium Escherichia coli (DnaKEc) were functionally similar when assayed in vitro but DnaKMm failed to substitute for DnaKEc in vivo. Searching for the molecular basis of the observed DnaK species specificity we compared substrate binding by DnaKMm and DnaKEc. DnaKMm showed a lower affinity for the model peptide (a-CALLQSRLLS) compared to DnaKEc. Furthermore, it was unable to negatively regulate the E. coli σ32 transcription factor level under heat shock conditions and poorly bound purified σ32, which is a native substrate of DnaKEc. These observations taken together indicate differences in substrate specificity of archaeal and bacterial DnaKs. Structural modeling of DnaKMm showed some structural differences in the substrate-binding domains of DnaKMm and DnaKEc, which may be responsible, at least partially, for the differences in peptide binding. Size-exclusion chromatography and native gel electrophoresis revealed that DnaKMm was found preferably in high molecular mass oligomeric forms, contrary to DnaKEc. Oligomers of DnaKMm could be dissociated in the presence of ATP and a substrate (peptide) but not ADP, which may suggest that monomer is the active form of DnaKMm.
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Hsp70s are chaperone proteins that are conserved in evolution and present in all prokaryotic and eukaryotic organisms. In the archaea, which form a distinct kingdom, the Hsp70 chaperones have been found in some species only, including Methanosarcina mazei. Both the bacterial and archaeal Hsp70(DnaK) chaperones cooperate with a GrpE co-chaperone which stimulates the ATPase activity of the DnaK protein. It is currently believed that the archaeal Hsp70 system was obtained by the lateral transfer of chaperone genes from bacteria. Our previous finding that the DnaK and GrpE proteins of M. mazei can functionally cooperate with the Escherichia coli GrpE and DnaK supported this hypothesis. However, the cooperation was surprising, considering the very low identity of the GrpE proteins (26%) and the relatively low identity of the DnaK proteins (56%). The aim of this work was to investigate the molecular basis of the observed interspecies chaperone interaction. Infrared resolution-enhanced spectra of the M. mazei and E. coli DnaK proteins were almost identical, indicating high similarity of their secondary structures, however, some small differences in band position and in the intensity of amide I' band components were observed and discussed. Profiles of thermal denaturation of both proteins were similar, although they indicated a higher thermostability of the M. mazei DnaK compared to the E. coli DnaK. Electrophoresis under non-denaturing conditions demonstrated that purified DnaK and GrpE of E. coli and M. mazei formed mixed complexes. Protein modeling revealed high similarity of the 3-dimensional structures of the archaeal and bacterial DnaK and GrpE proteins.
Objectives. Recent epidemiological studies suggested an association between a poor vitamin D [25(OH)D] status, inflammatory mediators, and rheumatoid arthritis (RA). We have recently proposed that pro-inflammatory interleukin 6 (IL-6) may represent a good marker for disease activity of RA. The aim of this study was to investigate the relationship between serum 25(OH)D levels and disease activity, joint damage, as well as serum IL-6 levels in a Polish RA population. Materials and Methods. Serum 25(OH)D levels were measured in 35 female RA patients and 38 age- and gender-matched healthy controls. Statistical correlations between 25(OH)D levels and the disease activity score 28 (DAS 28), joint damage based on the Steinbrocker criteria, as well as serum IL-6 levels were performed. Results. There was no statistically significant difference between levels of 25(OH)D in RA (16.89±8.57 ng/ml) and healthy controls (14.12±7.51 ng/ml), and the vitamin D deficiency (<20 ng/ml) was found in 71.43% of RA patients and 73.68 % of healthy controls. While vitamin D status did not correlate with DAS 28 (r=0.265, p=0.149) and joint damage based on the Steinbrocker criteria (r=0.367, p=0.065), a positive correlation between 25(OH)D and IL-6 (r=0.537, p=0.002) was observed in RA. Conclusion. Although further studies on a larger group of patients will be needed to confirm the data presented here, it seems that hypovitaminosis D is common in the RA patients and middle-aged non-RA healthy women in the Polish population. 25(OH)D levels were similar in the RA patients and age- and gender-matched healthy controls, and were not associated with joint damage and disease activity in patients.
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Mast cells play an important role in both, the innate and adaptive immunity, however, clonal proliferation of abnormal mast cells in various organs leads to mastocytosis. A skin variant of the disease, cutaneous mastocytosis (CM) is the most frequent form of mastocytosis in children. HtrA proteases are modulators of important cellular processes, including cell signaling and apoptosis, and are related to development of several pathologies. The above and the observation that mast cells constitutively release the HtrA1 protein, prompted us to investigate a possible involvement of the HtrA proteins in pediatric CM. Levels of the serum autoantibodies (IgG) against the recombinant HtrA proteins (HtrA1-4) in children with CM (n=36) and in healthy controls (n=62) were assayed. Anti-HtrA IgGs were detected using enzyme linked immunosorbent assay (ELISA) and Western-blotting. In the CM sera, levels of the anti-HtrA1 and anti-HtrA3 autoantibodies were significantly increased when compared to the control group, while the HtrA protein levels were comparable. No significant differences in the anti-HtrA2 IgG level were found; for the anti-HtrA4 IgGs lower levels in CM group were revealed. In healthy children, the IgG levels against the HtrA1, -3 and -4 increased significantly with the age of children; no significant changes were observed for the anti-HtrA2 IgG. Our results suggest involvement of the HtrA1 and HtrA3 proteins in pediatric CM; involvement of the HtrA4 protein is possible but needs to be investigated further. In healthy children, the autoantibody levels against HtrA1, -3 and -4, but not against HtrA2, increase with age.
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