Identification of an α(1→6) mannopyranosyltransferase (MptA), involved in Corynebacterium glutamicum lipomanann biosynthesis, and identification of its orthologue in Mycobacterium tuberculosis

Corynebacterium glutamicum and Mycobacterium tuberculosis share a similar cell wall architecture, and the availability of their genome sequences has enabled the utilization of C. glutamicum as a model for the identification and study of, otherwise essential, mycobacterial genes involved in lipomannan (LM) and lipoarabinomannan (LAM) biosynthesis. We selected the putative glycosyltransferase-Rv2174 from M. tuberculosis and deleted its orthologue NCgl2093 from C. glutamicum. This resulted in the formation of a novel truncated lipomannan (Cg-t-LM) and a complete ablation of LM/LAM biosynthesis. Purification and characterization of Cg-t-LM revealed an overall decrease in molecular mass, a reduction of α(1→6) and α(1→2) glycosidic linkages illustrating a reduced degree of branching compared with wild-type LM. The deletion mutant's biochemical phenotype was fully complemented by either NCgl2093 or Rv2174. Furthermore, the use of a synthetic neoglycolipid acceptor in an in vitro cell-free assay utilizing the sugar donor β-d-mannopyranosyl-1-monophosphoryl-decaprenol together with the neoglycolipid acceptor α-d-Manp-(1→6)-α-d-Manp-O-C8 as a substrate, confirmed NCgl2093 and Rv2174 as an α(1→6) mannopyranosyltransferase (MptA), involved in the latter stages of the biosynthesis of the α(1→6) mannan core of LM. Altogether, these studies have identified a new mannosyltransferase, MptA, and they shed further light on the biosynthesis of LM/LAM in Corynebacterianeae

Mycobacterium tuberculosis phagosome

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75241/1/j.1365-2958.1999.01279.x.pd

Mycobacterium smegmatis laminin-binding glycoprotein shares epitopes with Mycobacterium tuberculosis heparin-binding haemagglutinin

Mycobacterium tuberculosis, the causative agent of tuberculosis, produces a heparin-binding haemagglutinin adhesin (HBHA), which is involved in its epithelial adherence. To ascertain whether HBHA is also present in fast-growing mycobacteria, Mycobacterium smegmatis was studied using anti-HBHA monoclonal antibodies (mAbs). A cross-reactive protein was detected by immunoblotting of M. smegmatis whole-cell lysates. However, the M. tuberculosis HBHA-encoding gene failed to hybridize with M. smegmatis chromosomal DNA in Southern blot analyses. The M. smegmatis protein recognized by the anti-HBHA mAbs was purified by heparin-Sepharose chromatography, and its amino-terminal sequence was found to be identical to that of the previously described histone-like protein, indicating that M. smegmatis does not produce HBHA. Biochemical analysis of the M. smegmatis histone-like protein shows that it is glycosylated like HBHA. Immunoelectron microscopy demonstrated that the M. smegmatis protein is present on the mycobacterial surface, a cellular localization inconsistent with a histone-like function, but compatible with an adhesin activity. In vitro protein interaction assays showed that this glycoprotein binds to laminin, a major component of basement membranes. Therefore, the protein was called M. smegmatis laminin-binding protein (MS-LBP). MS-LBP does not appear to be involved in adherence in the absence of laminin but is responsible for the laminin-mediated mycobacterial adherence to human pneumocytes and macrophages. Homologous laminin-binding adhesins are also produced by virulent mycobacteria such as M. tuberculosis and Mycobacterium leprae, suggesting that this adherence mechanism may contribute to the pathogenesis of mycobacterial diseases

Targeting innate immunity for tuberculosis vaccination

Vaccine development against tuberculosis (TB) is based on the induction of adaptive immune responses endowed with long-term memory against mycobacterial antigens. Memory B and T cells initiate a rapid and robust immune response upon encounter with Mycobacterium tuberculosis, thus achieving long-lasting protection against infection. Recent studies have shown, however, that innate immune cell populations such as myeloid cells and NK cells also undergo functional adaptation after infection or vaccination, a de facto innate immune memory that is also termed trained immunity. Experimental and epidemiological data have shown that induction of trained immunity contributes to the beneficial heterologous effects of vaccines such as bacille Calmette-Guerin (BCG), the licensed TB vaccine. Moreover, increasing evidence argues that trained immunity also contributes to the anti-TB effects of BCG vaccination. An interaction among immunological signals, metabolic rewiring, and epigenetic reprogramming underlies the molecular mechanisms mediating trained immunity in myeloid cells and their bone marrow progenitors. Future studies are warranted to explore the untapped potential of trained immunity to develop a future generation of TB vaccines that would combine innate and adaptive immune memory induction

OMERACT Endorsement of Measures of Outcome for Studies of Acute Gout

Objective:To determine the extent to which participants at the Outcome Measures in Rheumatology (OMERACT) 11 meeting agree that instruments used in clinical trials to measure OMERACT core outcome domains in acute gout fulfill OMERACT filter requirements of truth, discrimination, and feasibility; and where future research efforts need to be directed. Methods. Results of a systematic literature review and analysis of individual-level data from recent clinical studies of acute gout were presented to OMERACT participants. The information was discussed in breakout groups, and opinion was defined by subsequent voting in a plenary session. Endorsement was defined as at least 70% of participants voting in agreement with the proposition (where the denominator excluded those participants who did not vote or who voted "don't know"). Results. The following measures were endorsed for use in clinical trials of acute gout: (1) 5-point Likert scale and/or visual analog scale (0 to 100 mm) to measure pain; (2) 4-point Likert scale for joint swelling; (3) 4-point Likert scale for joint tenderness; and (4) 5-point Likert scale for patient global assessment of response to treatment. Measures for the activity limitations domain were not endorsed. Conclusion. Measures of pain, joint swelling, joint tenderness, and patient global assessment in acute gout were endorsed at OMERACT 11. These measures should now be used in clinical trials of acute gout