CsrA is a global regulator that binds to two sites in the glgCAP leader transcript, thereby blocking ribosome access to the glgC Shine-Dalgarno sequence. The upstream CsrA binding site (GCACACGGAU) was used to search the Escherichia coli genomic sequence for other genes that might be regulated by CsrA. cstA contained an exact match that overlapped its Shine-Dalgarno sequence. cstA was previously shown to be induced by carbon starvation and to encode a peptide transporter. Expression of a cstA-lacZ translational fusion in wild-type and csrA mutant strains was examined. Expression levels in the csrA mutant were approximately twofold higher when cells were grown in Luria broth (LB) and 5-to 10-fold higher when LB was supplemented with glucose. It was previously shown that cstA is regulated by the cyclic AMP (cAMP)-cAMP receptor protein complex and transcribed by ⌭ 70 . We investigated the influence of S on cstA expression and found that a S deficiency resulted in a threefold increase in cstA expression in wild-type and csrA mutant strains; however, CsrA-dependent regulation was retained. The mechanism of CsrA-mediated cstA regulation was also examined in vitro. Cross-linking studies demonstrated that CsrA is a homodimer. Gel mobility shift results showed that CsrA binds specifically to cstA RNA, while coupled-transcription-translation and toeprint studies demonstrated that CsrA regulates CstA synthesis by inhibiting ribosome binding to cstA transcripts. RNA footprint and boundary analyses revealed three or four CsrA binding sites, one of which overlaps the cstA ShineDalgarno sequence, as predicted. These results establish that CsrA regulates translation of cstA by sterically interfering with ribosome binding.

SummaryThe global regulatory Csr (carbon storage regulator) and the homologous Rsm (repressor of secondary metabolites) systems of Gram-negative bacteria typically consist of an RNA-binding protein (CsrA/RsmA) and at least one sRNA that functions as a CsrA antagonist. CsrA modulates gene expression posttranscriptionally by regulating translation initiation and/or mRNA stability of target transcripts. While Csr has been extensively studied in Gram-negative bacteria, until now Csr has not been characterized in any Gram-positive organism. csrA of Bacillus subtilis is the last gene of a flagellum biosynthetic operon. In addition to the previously identified s D -dependent promoter that controls expression of the entire operon, a s A -dependent promoter was identified that temporally controls expression of the last two genes of the operon (fliW-csrA); expression peaks 1 h after cell growth deviates from exponential phase. hag, the gene encoding flagellin, was identified as a CsrAregulated gene. CsrA was found to repress hagЈ-ЈlacZ expression, while overexpression of csrA reduces cell motility. In vitro binding studies identified two CsrA binding sites in the hag leader transcript, one of which overlaps the hag Shine-Dalgarno sequence. Toeprint and cell-free translation studies demonstrate that bound CsrA prevents ribosome binding to the hag transcript, thereby inhibiting translation initiation and Hag synthesis.

Background. Systemic sclerosis (SSc, scleroderma) is a disorder characterized by fibrosis of skin and visceral organs. Pathogenesis of scleroderma is complex and is incompletely understood as yet. Autoantibodies in SSc represent a serologic hallmark which have clinical relevance, with diagnostic and prognostic potential. Objectives. To study distribution of clinical manifestations and to identify frequency of autoantibodies among subtypes of scleroderma patients from Western India. Methodology. One hundred and ten scleroderma patients were clinically classified according to the American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) criteria. All these patients were in active stage of disease. Clinical manifestations were recorded at the time of presentation. Autoantibodies were tested in them by indirect immunofluorescence test and ELISA. Immunoglobulin levels were estimated by nephelometer. These parameters were further correlated with clinical presentation of the disease. Results. Scleroderma patients had M : F ratio of 1 : 10 where mean age at evaluation was 34.7 ± 10.7 years and a mean disease duration was 43.7 ± 35 months. Clinical subtypes showed that 45 patients (40.9%) had diffused cutaneous (dcSSc) lesions, 32 patients (29.1%) had limited cutaneous (lcSSc) lesions, and 33 patients (30%) had other autoimmune overlaps. The overall frequency of ANA in SSc patients studied was 85.5%. The frequency of anti-Scl70, anti-centromere, anti-endothelial cell antibodies (AECA), and anti-keratinocyte antibodies (AKA) was 62.7%, 22.7%, 30%, and 40.9%, respectively. Anti-Scl70 antibodies were significantly high (75.6% versus 46.9%) among dcSSc patients (P < 0.0115) whereas anti-centromere antibodies were significantly high (9% versus 38%) among lcSSc patients when these two subtypes were compared (P < 0.0044). Conclusion. This study supports that there are geoepidemiological variations among scleroderma patients for their clinical presentation, autoantibody profile, and immune parameters across the country.

Systemic lupus erythematosus (SLE) is characterized by over production of autoantibodies. C-reactive protein (CRP) is a phylogenetically highly conserved plasma protein that participates in the systemic response to inflammation. Anti-CRP antibodies might have biological functions of pathogenetic interest in SLE. We evaluated anti-CRP antibodies in Indian SLE patients and their association with anti-dsDNA antibodies and complement levels (C3 and C4). One hundred SLE patients diagnosed according to the American College of Rheumatology criteria were included. Disease activity was assessed using SLE disease activity index (SLEDAI). Anti-CRP autoantibodies were detected by enzyme linked immunosorbent assay. Anti-dsDNA antibodies were detected by indirect immunofluroscence test (Euroimmun Lubeck, Germany). High sensitivity CRP and complement levels (C3, C4) were detected using a Nephelometer. (BN ProSpec, Dade Behring, Germany). Anti-CRP antibodies were detected in 26% of SLE patients. Mean age of disease onset among anti-CRP positives was 22.4 ± 7.5, and 26.6 ± 9.3 years among anti-CRP negatives (P > 0.05). Anti-dsDNA positivity was significantly higher among anti-CRP positives (32.7%) as compared to anti-CRP negatives (16%) (P = 0.00519). No statistically significant difference was observed in SLEDAI scores of anti-CRP positive group and anti-CRP negative group (P > 0.05). We observed a positive correlation between anti-CRP antibodies and anti-dsDNA antibodies.